Patent Application
20070026990
This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2005-218000, filed on Jul. 27, 2005, and Japanese Patent Application 2005-221016, filed on Jul. 29, 2005, the entire content of which is incorporated herein by reference.
This invention generally relates to an oil pressure control apparatus for an automatic transmission that controls directly an oil pressure, which is supplied from an oil pressure source, by a linear solenoid valve. More particularly, this invention pertains to improvement of durability and reliability of an oil pressure control apparatus for an automatic transmission against electric disconnection failure.
Japanese examined patent publication No. 5-63664 (reference 1) discloses a transmission control apparatus which includes solenoid valves at the same number as frictional engagement elements and is capable of selectively establishing six forward shift stages. In this transmission control apparatus, there are five solenoid valves (e.g., linear solenoid valves) each for the frictional engagement elements C1, C2, C3, C4 and C5; a single ON/OFF solenoid valve; and two shift valves. In the event of an electric disconnection failure mode (electric interruption), an automatic shift operation (1st-3rd, 2nd to 5th-4th, 6th-5th) is implemented in response to a currently selected shift stage.
Japanese patent No. 2925505 (reference 2) and Japanese patent No. 2925506 (reference 3) each disclose a transmission control apparatus including therein five frictional engagement elements. The five frictional engagement elements are frictionally engaged by use of two solenoid valves; three shift valves; and three ON/OFF solenoid valves controlling the shift valves so that six forward shift stages can be established in the transmission. This transmission control apparatus implements a shift operation by introducing a line pressure to at least a predetermined frictional engagement element from among the five frictional engagement elements and by changing the frictional engagement elements to be frictionally engaged in response to an operation of the solenoid valves. In the event of an electric disconnection failure mode (electric interruption), a shift stage, which can be established in the transmission, is controlled to be a predetermined shift stage apart from the first and sixth shift stage or a shift stage higher than the predetermined shift stage.
However, in the structures disclosed in the references 2 and 3, a jumping shift operation (hereinafter, referred to as a skip shift operation), such as a shift operation from the third shift stage to the fifth shift stage, from the second shift stage to the fourth shift stage, from the fourth shift stage to the sixth shift stage and vice versa, can not be achieved. For example, in order to attempt a skip shift from the third shift stage to the fifth shift stage, a shift operation step by step such as from the third shift stage to the fifth shift stage via the fourth shift stage needs to be performed. This type of operation, however, may give an operator a feeling such as excessive shift operation, responsibility degradation.
In the light of the foregoing, being compared with the number of respective components in each reference 2 and 3, U.S. Pat. No. 6,585,617 (reference 4) discloses an electro-hydraulic control system for a multi-speed power transmission which includes therein: four linear solenoid valves (added another two), two shift valves (reduced one), and an ON/OFF solenoid valve (reduced two). Further, a single oil pressure switch (hereinafter referred to as an oil pressure SW) is added to this electro-hydraulic control system disclosed in the reference 4 so that a skip shift operation between the second shift stage and the sixth shift stage is carried out.
Under the garage shift operation (R-N-D, D-N-R), an ON/OFF solenoid valve 1 (hereinafter referred to as S1) switches a shift valve 1 (hereinafter referred to as SV1), and a linear solenoid valve 1 (hereinafter referred to as SL1) switches a shift valve 2 (hereinafter referred to as SV2). When the ON/OFF solenoid valve S1 is switched ON (∘) and the shift valve SV1 is operated to an ON-side, the line pressure PL is supplied to a linear solenoid valve SL2 so that the linear solenoid valve SL2 is operated.
For example, as is obvious from
Meanwhile, when a shift range is to be shifted from the N range to the D range, likewise, after frictionally engaging the brake B2 (C5), the linear solenoid valve SL1 is gradually controlled to an engagement side by a drive pressure (D pressure) already being supplied to the linear solenoid valve SL1. As a result, the clutch C1 is engaged. Therefore, a possible garage shock, which may occur due to the frictional engagement of the clutch C1, can be reduced, and a first shift stage is established in the transmission. Further, a linear solenoid valve 4 (hereinafter referred to as SL4), which has been supplied with the D pressure, is controlled to an engagement side, and so the brake B1 (C4) is frictionally engaged, while the brake B2 (C5) is released from the engagement in response to a control of the linear solenoid valve SL2 to a release side. As a result, a shift stage in the automatic transmission is shifted to the second shift stage, as being summarized in a pattern of a 1-2 shift operation at the D range of
Next, when the ON/OFF solenoid valve S1 is switched OFF (×) from an ON-state (∘), the line pressure (PL pressure) is supplied to the shift valves SV1 and SV2, and the oil pressure SW is turned on. The shift valve SV2 is hence maintained at the ON-state (∘) in favor of a step of the shift valve SV2, and the line pressure (PL pressure) is hence supplied to the linear solenoid valve SL3. Further, with the shift valve SV1 switched off (×), the linear solenoid valve SL2, which had communicated with the brake B2 (C5), then communicates with the clutch C2. The frictional engagement elements C1, C2, C3 and B1 (C4) are controlled independently, thereby enabling to freely establish a shift stage between the second shift stage and the sixth shift stage.
Meanwhile, according to the configuration disclosed in the reference 4, at a time of an occurrence of an all electric disconnection failure, the ON/OFF solenoid valve S1 and the shift valve SV1 is at the OFF-state (×), as being summarized in a pattern at a D-range during electric disconnection failure. In such circumstances, the NH-type linear solenoid valves SL2 and t SL3 are controlled to the engagement side, and the clutch C1 and the brake C3 are frictionally engaged. The third shift stage is hence established in the transmission. However, when the linear solenoid valve SL2 is controlled to the engagement side in a state of a multiple shift pattern with the ON/OFF solenoid valve S1 at the OFF-state (×) and the shift valve SV1 at the ON-state (∘), the PL pressure latches the shift valve SV2 to the on side. The linear solenoid valve SL2 is then kept communicating with the clutch C2 and the fifth shift stage is established with the clutch C2 and the brake C3 engaged in the transmission. Therefore, even at a time of all electric disconnection failure while a shift stage from among the fourth, fifth and sixth shift stages is being selected with the linear solenoid valves SL2 and the clutch C2, an actual shift stage in the transmission is controlled at the fifth shift stage and a speed reduction shock can be precluded. When a vehicle needs to re-start, a limping can be performed at the third shift stage. Further, at a time of all electric disconnection failure while the ON/OFF solenoid valve S1 is at the ON-state (∘) and the shift valve SV1 is at the OFF-state (×), only the brake B2 (C5) is frictionally engaged and a neutral shift stage is established.
As described above, according to the configuration of the reference 4, electric disconnection failure approach and a skip shift, which both could not be solved by the references 1, 2 and 3, are solved. However, the following matters still need to be considered.
Fist of all, being compared with a simple configuration each disclosed in the references 2 and 3, cost advantages are lost according to the configuration of the reference 4. For example, being compared with a simple configuration disclosed in the references 2 and 3, it may be inevitable to add another two to the linear solenoid valves in each reference 2 and 3, so that a skip shift can be achieved. However, the configuration disclosed in the reference 4 requires totally five oil pressure switches (added one). On the other hand, being compared with a simple configuration each disclosed in the references 2 and 3, the total number of the ON/OFF solenoid valves is reduced from three to one, and the total number of the shift valves is reduced from two to one. However, the reference 4 requires another oil pressure SW additionally. Because an oil pressure SW is expensive, this addition may cancel the aforementioned cost reduction. As a result, the additional two linear solenoid valves increase the manufacturing cost of the system disclosed in the reference 4.
15] Further, the configuration of the reference 4 excels in solving electric disconnection failure more than the configurations of the references 2 and 3. However, the electric disconnection failure can be solved on the assumption that the NL-type linear solenoid valves are turned off at a time of electric disconnection. Here, we will consider a case of an ON-failure of the NL-type linear solenoid valves. For example, in the event that the linear solenoid valve SL4 (NL) suffers from an ON-failure due to a short-circuit or a foreign obstacle while the sixth shift stage is being selected with the clutch C2 (linear solenoid valve SL2) and the brake B1 (C4) (linear solenoid valves SL4) frictionally engaged, a down-shift operation, such as 6th to 5th shift stage (C2 and C3 engaged), 6th to 4th (C1 and C2 engaged), and so on, may be performed in accordance with a predetermined shift map. In such circumstances, interlocking may occur, and the oil pressure SW detects the interlocking and an actually selected shift stage in the transmission is controlled to return to the sixth shift stage.
Electric disconnection failure is assumed to have occurred to the linear solenoid valve SL3 (NH), which is a secondary failure, while the vehicle is running under the above-described condition. In this case, even if the linear solenoid valve SL2 is controlled to the ON-side and the clutch C2 is released from the engagement, the brake C3 (SL3) and the brake B1 (C4) are both frictionally engaged so that any shift stage can not be selected and a planetary gear-locking may occur.
In the light of the foregoing, shift patterns can be changed so that the above problem could be solved. However, the same state or event is generated even during the all electric disconnection mode, in which both the ON/OFF solenoid valve S1 and the shift valve SV1 are at the OFF-state (×). It is hence necessary to control the ON/OFF solenoid valve S1 at the ON-state (∘) and to control the SV at the OFF-state (×). Alternatively, it is hence necessary to control both the ON/OFF solenoid valve S1 and the shift valve SV1 at the ON-state (∘). However, if the ON/OFF solenoid valve S1 is switched from the OFF-state (×) to the ON-state (∘) in state where the sixth shift stage is being selected with the clutch C2 (linear solenoid valve SL2) and the B1 (C4) (linear solenoid valve SL4) engaged, there is a danger that the output shaft is locked. Therefore, prior to this change, it is necessary to control the linear solenoid valve SL2 to the ON-side and to control the linear solenoid valve SL2 to the disengagement side, i.e., to control an output pressure of the linear solenoid valve SL2 to be OFF. However, in response to the control of the linear solenoid valve SL2 to the disengagement side, the shift valve SV2, which had been latched by the output pressure of the linear solenoid valve SL2, is switched to the OFF-state by a spring force. As a result, a shift range is shifted to the N range, in which only the brake C4 (B1) has been engaged, and a driving force will disappears.
The secondary failure, in which the linear solenoid valve SL3 (NH) is an OFF-failure, was described above. Likewise, in the event of the OFF-failure of the linear solenoid valve SL2 (NH), which is a secondary failure, a shift rage is forced to the N range, according to the configuration disclosed in the reference 4.
19] If all electric disconnection occurs due to an OFF-operation of an ignition key by an operator, a cable dropping due to vibration, fuse blowing due to excessive current, or the like, during the ON-failure of the linear solenoid valve SL4, the ON/OFF solenoid valve S1 and the shift valve SV1 are switched to the OFF-state (×), as being summarized in the pattern at the D-range of
Further, as is obvious from
Further, JP2005-024059A (reference 5) discloses an oil pressure control circuit in which plural change valves are provided between solenoid valves and frictional engagement elements. The plural change valves serve as a fail-safe mechanism against the OFF-failure of the solenoid valves. When the solenoid valves are at the OFF-failure, the frictional engagement element corresponding to the position of the change valves is supplied with a D-position pressure PD, and a vehicle can run at an appropriate shift stage.
As illustrated in
As a direct driven type linear solenoid valve, there are two types of valves: a normal low type valve (NL), which is controlled to a disengagement side in the event of disconnection failure and a normal high type valve (NH), which is controlled to an engagement side in the event of disconnection failure. An NL-type valve have been practically used, which can assure a requisite amount of oil with high precision. Meanwhile, currently, no NH-type valve, which can contribute to an automatic transmission in which a clutch-to-clutch control should be performed, is present currently. In order for the NH-type solenoid valve to assure a requisite amount of oil and to raise an output pressure in response to reduction in an indicated current, a spring force can be designed to be greater. However, if a force of a spring, which is housed in a limited space, is increased, there is a danger that a biasing performance may deteriorate due to fluctuations of spring loads. Further, it is possible to reduce a diameter of a spool valve, in order for the NH-type solenoid valve to assure a requisite amount of oil and to raise an output pressure. However, in this case, it is apparent that the solenoid valve may not be able to output oil at a large amount if the diameter of the spool valve is reduced.
241 Therefore, if all the linear solenoid valves, which are employed in an oil pressure control apparatus for an automatic transmission, are the aforementioned directly driven type, in view of a cost or space matter, only a normal low-type linear solenoid valve is applicable. However, an actually selected shift stage may not be maintained in the event of electric disconnection failure.
The reference 5 discloses an approach with an OFF-failure safe mechanism for an oil pressure circuit with only the normal low-type linear solenoid valves. Practically speaking, in addition to the Off-failure change valves, so-called ON-failure change valves are required. Moreover, in the condition where these plural change valves are provided at a downstream side of the linear solenoid valves and are disconnected from the line pressure or branch (communication with a drain), a length of an oil passage between each solenoid valve and a corresponding frictional engagement element is increased, which may hinder a downsizing of an oil pressure control apparatus, and in addition may cause an oil pressure vibration. Further, if another consideration is given to locking or sticking of a valve body of a change valve, there is a danger that a vehicle can not keep running at an actually selected shift stage, in the event of the failure. As described above, the conventional works still discloses a possible approach for maintaining an actually selected shift stage, at the event of electric disconnection failure.
As described above, some of the conventional works disclose that both a slip shift operation and electric disconnection failure approach can be settled by use of the limited number of linear solenoid valves. However, these approaches still needs to be costly improved and should be improved in durability against the second and third failures. Further, it is necessary to provide an oil pressure control apparatus for an automatic transmission, the apparatus which can employ any types of solenoid valves and excels in durability and reliability against electric disconnection failure in addition manufacturing cost and space.
According to an aspect of the present invention an oil pressure control apparatus for an automatic transmission includes: plural frictional engagement elements engageable and disengageable and operated to establish plural N forward shift stages by being engaged or disengaged; solenoid valves allocated for at least a corresponding frictional engagement element among from the plural frictional engagement elements and operated to achieve an automatic shift mode in which the plural N forward shift stages are switched; a controller for controlling oil pressure supplied to the frictional engagement elements via the solenoid valves so that engagement and disengagement of the frictional engagement elements are controlled; and shift valves shifted ON and OFF by the controller in accordance with a shift pattern for each shift stage among from the plural N forward shift stages and configured to establish an oil passage between the respective solenoid valves and the at least corresponding frictional engagement element by being shifted ON and OFF. A specific combination of ON and OFF states of the shift valves is assigned to an automatic shift pattern for operating the solenoid valves for each shift stage of the automatic shift mode. One of other combinations of the ON and OFF states of the shift valves is assigned to a first fixed shift pattern of a first forward shift stage at which two predetermined solenoid valves from among the solenoid valves are employed. The other one of the other combinations is assigned to a second fixed shift pattern of a second forward shift stage at which other solenoid valves from among the solenoid valves are employed, one of the first and second fixed shift patterns being selected in response to operations of the shift valves for driving a vehicle.
The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings, wherein:
Embodiments of the present invention will be described hereinbelow with reference to the attached drawings. An oil pressure control apparatus according to the embodiments of the present invention includes an ECU (Electronic Control Unit; not illustrated), three shift valves (shift valves SV1, SV2, and SV3), and three solenoid valves (solenoid valves S1, S2, and S3) which respectively switch the shift valves SV1, SV2, SV3 on and off. With reference to a D-range in
According to the embodiments of the present invention, six forward shift stages can be established by an appropriate combination of five frictional engagement elements. In the second automatic shift pattern, in which the lower shift operation can be performed, three linear solenoid valves SL1, SL2, and SL4 out of four linear solenoid valves SL1, SL2, SL3, SL4 are controlled for shifting from a first shift stage to a second shift stage and for shifting from the second shift stage to the first shift stage (1st-2nd), as illustrated in the automatic shift pattern 1-2 at the D-range in
With reference to
A normal high type (hereinafter, referred to as NH) linear solenoid valve holds an engagement of the frictional engagement element at the time of disconnection of the linear solenoid valve, while a normal low type (hereinafter, referred to as NL) linear solenoid valve releases the engagement thereof at the time of disconnection of the linear solenoid valve. Two of the four linear solenoid valves, which are the linear solenoid valve SL2 and one of linear solenoid valve SL1 and linear solenoid valve SL3, are NH type, and the other linear solenoid valves are NL type. A fixed shift stage (fifth shift stage), which is employed in the event of all electric disconnection at which two linear solenoid valves are used, and a fixed shift stage, which is employed in the event of the ON-failure of the NL-type linear solenoid valve at which at least one NH-type linear solenoid valve is used, are established by a selected combination of,the shift valves. Therefore, it is possible to preclude an impossibility of engagement of the frictional engagement elements, the impossibility which may occur due to the all-electric disconnection as a primary failure. It is further possible to avoid a possible interlock due to an ON-failure of the NL-type linear solenoid valve.
Illustrated in
As illustrated in
According to an example shown in
However, as described above, if all the linear solenoid valves are changed into NH type, an interlock may be created at the primary failure during a shift mode. Therefore, a fail-safe valve, or the like, is required for preventing the interlock and the number of components may thereby be increased and oil passage structures may thereby be complicated. Further, the oil passages may be configured in such a manner that target frictional engagement elements (the clutch C1 and the brake B1) are supplied with line pressure by interrupting output oil passages by means of the shift valve. However, it may cause the NL-type linear solenoid valves SL1 and SL4 at the upstream side of the shift valves against a disconnection failure. Further, it may lose an oil passage configuration illustrated in
A first embodiment of the present invention will be explained hereinafter. The oil pressure control apparatus according to the first embodiment of the present invention is applicable for a direct pressure type linear solenoid valve shown in
According to the first embodiment of the present invention, the brake B2 is divided into two brakes such as a brake B2S with a small piston oil chamber and a brake B2L with a large piston oil chamber. The other structure of the oil pressure control apparatus according to the first embodiment is similar to that of the oil pressure control apparatus illustrated in
As illustrated in
In order to supply the line pressure to the exhaust port of the NL type linear solenoid valve SL1, forward pressure (hereinafter, referred to as D pressure) is supplied to the exhaust port of the linear solenoid valve SL1 only in a condition where the solenoid valves S1 and S3 are at the OFF-state (×), and so the first shift stage and the third shift stage of the fixed shift pattern can be selected by an operation of the ON/OFF solenoid valve S2. On this occasion, the fixed shift pattern is limited to the first shift stage and the third shift stage for minimizing the increase in the number of the oil passages. However, if there is a space, the vehicle can be driven at all fixed shift stages at the time of all disconnection, which is described according to the other embodiments of the present invention described below.
As is obvious from
At the first fixed shift stage pattern, the line pressure is directly supplied to the clutch C1. It means that a lock valve or a gain switching valve are not additionally required in a condition where a pressure more than the maximum output pressure of the linear solenoid valve is required at the time of start from torque converter stall, or the like. Accordingly, the oil passage according to the first embodiment of the present invention can be simplified and a manufacturing cost thereof can be reduced.
The oil passage structure according to the first embodiment of the present invention is further provided with an oil passage 111 for transmitting reverse pressure (hereinafter, referred to as R pressure) to a switching circuit of the shift valve SV1 and an oil passage 112 for transmitting the R pressure to the shift valve SV2 to forcibly turn on the shift valve SV2, instead of adding another shuttle valve. Therefore, even in a condition where the shift valve SV1 is at the OFF-state (×), as far as the R pressure is being supplied to the shift valve SV1, the clutch C3 used for a reverse shift stage can be engaged by means of the linear solenoid valve SL3 by turning on the shift valve SV2.
The oil passage structure according to the first embodiment of the present invention is still further provided with an oil passage 121 for transmitting the D pressure, which was sent from the switching circuit of the shift valve SV1 to the shift valve SV2, to the switching circuit of the shift valve SV3 and an oil passage 122 communicating with a shuttle valve connected to the brake B2S. In a condition where the shift valve SV1 is at the OFF-state (×), the shift valve SV2 is at the ON-state (∘), and the shift valve SV3 is at the OFF-state (×), the D pressure is supplied to the brake B2S, and the brake B2L having larger dimensions communicate with the linear solenoid valve SL2. With the above structure, in proportion to an increase in a required torque capacity because of the increased number of shift stages in the transmission and in order to reduce a manufacturing cost and a space, use of a 1-2 one-way clutch (i.e., O.W.C) can be abolished. More particularly, even in the event that the OFF-failure occurs to the NL-type linear solenoid valve SL2, the vehicle can be started on the first shift stage with the brake B2S engaged, and a coast control can be carried out.
According to an example shown in
An operation of the oil pressure control apparatus according to the first embodiment of the present invention at each shift pattern will individually be explained hereinafter.
[D-range 1st-2nd Automatic Shift Mode]
An oil passage for transmitting the D pressure to the shift valve SV1 through a third bottom switching circuit of the shift valve SV3 is interrupted because the shift valve SV1 is at the OFF-state (×), and the D pressure is thereby not transmitted to a supply port of the linear solenoid valve SL3. Further, the D pressure transmitted through a first top switching circuit of the shift valve SV1 is interrupted by the shift valves SV2 and SV3 and is not supplied to the brake B2S and the exhaust port of the linear solenoid valve SL1. An output oil passage of the linear solenoid valve SL2 reaches the brake B2L through a first bottom switching circuit of the shift valve SV1, a first bottom switching circuit of the shift valve SV2, and a shuttle valve (i.e., check ball valve).
Accordingly, the clutch C1 (SL1), the brake B1 (SL4), and the brake B2L (SL2) can be controlled. Therefore, the automatic lower-shift pattern can be achieved, in which the first shift stage with the clutch C1 (SL1) and the brake B2L (SL2) engaged and the second shift stage with the clutch C1 (SL1) and the brake B1 (SL4) engaged are shifted mutually.
[D-range 2nd-6th Automatic Shift Mode]
Although there is an oil passage for transmitting the D pressure to the first top switching circuit of the shift valve SV1, the oil passage is interrupted because the shift valve SV1 is at the ON-state (∘). Therefore, the D pressure does not reach the brake B2S and the exhaust port of the linear solenoid valve SL1.
Accordingly, the clutch C1 (linear solenoid valve SL1), the clutch C2 (linear solenoid valve SL2), the clutch C3 (linear solenoid valve SL3), and the brake B1 (linear solenoid valve SL4) can be controlled, and the automatic shift pattern at the middle shift stages can be established in which a skip shift operation can be implemented. The linear solenoid valves SL2 and SL3 are NH-type so that the fifth shift stage can be established automatically during electric disconnection of all the linear solenoid valves.
[D-range 1st Fixed Shift Mode]
Because the solenoid valve S3 is at the OFF-state (×), the D pressure is interrupted at the second bottom switching circuit of the shift valve SV3 and does not reach the supply port of the linear solenoid valve SL4. Further, the D pressure transmitted through a second top switching circuit of the shift valve SV3 is interrupted at the third bottom switching circuit of the SV2 and does not reach the supply port of the linear solenoid valve SL3.
Accordingly, the clutch C1 (D pressure), the brake B2S (D pressure), and the brake B2L (SL2) are engaged and the first shift stage is thereby established. On this occasion, even in the event that the OFF-failure occurs to the linear solenoid valve SL2 which activates the brake B2L, the coast control is implemented by means of the brake B2S. Further, it may be difficult to start from the torque converter stall, however the vehicle can be driven at the first shift stage.
[D-range 2nd Fixed Shift Mode]
Because the D pressure transmitted through the third bottom switching circuit of the shift valve SV3 is interrupted at the third bottom switching circuit of the shift valve SV1, the D pressures is not supplied to the supply port of the linear solenoid valve SL3. Further, although the D pressure transmitted through the first top switching circuit of the shift valve SV1 also reaches the first top switching circuit of the shift valve SV3, the D pressure is interrupted at the first top switching circuit of the shift valve SV3 and is not supplied to the brake B2S and the exhaust port of the linear solenoid valve SL1. Accordingly, the clutch C1(SL1) and the brake B1 (SL4) are engaged and the second shift stage is thereby established.
[D-range 3rd Fixed Shift Mode]
In the aforementioned condition, the D pressure to the supply port of the linear solenoid valve SL4 is interrupted at the second bottom switching circuit of the shift valve SV3. Accordingly, the clutch C1 (D pressure) and the clutch C3 (SL3) are engaged and the third shift stage is thereby established. As a result, the vehicle can be driven not only in a condition where all the linear solenoid valves are disconnected but also in a condition where all the solenoid valves including the ON/OFF solenoid valves are disconnected.
[D-range 4th Fixed Shift Mode]
Because the ON/OFF solenoid valve S3 is at the OFF-state (×), the D pressure is interrupted at the second bottom switching circuit of the shift valve SV3 and is not reached to the supply port of the linear solenoid valve SL4. Further, the D pressure transmitted through the second top switching circuit of the shift valve SV3 is interrupted at the third bottom switching circuit of the shift valve SV2 and is not reached to the supply port of the linear solenoid valve SL3. Accordingly, the clutch C1 (SL1) and the clutch C2 (SL2) are engaged and the fourth shift stage is thereby established.
[D-range 5th Fixed Shift Mode]
The D pressure does not reach the supply port of the linear solenoid valve SL4, the supply port of the linear solenoid valve SL1, the exhaust port of the linear solenoid valve SL1, and the brake B2S because the D pressure is interrupted at the second bottom switching circuit of the shift valve SV3, the first top switching circuit of the shift valve SV2, and the first top switching circuit of the shift valve SV1. Accordingly, the clutch C2 (SL2) and the clutch C3 (SL3) are engaged and the fifth shift stage is thereby established. On this occasion, the vehicle can be driven in a condition where all the linear solenoid valves are disconnected.
When all solenoid valves are disconnected in a condition where the fourth shift stage or a higher shift stage than the fourth shift stage is established in which the clutch C2 is engaged, because pressure of the clutch C2 (SL2) latches the shift valve SV1 to the ON-side (∘), the shift valve SV1 is remained at ON-state (∘) without switching even in a condition where the ON/OFF solenoid valve S1 comes to the OFF-state (×) from the ON-state (∘). Therefore, the vehicle can be driven at the fifth shift stage. According to the embodiment of the present invention, when the disconnection of all the linear solenoid valves is generated in a condition where the vehicle is driven at the fourth shift stage or at the higher shift stage than the fourth shift stage at the second through sixth shift mode (the 2-n automatic shift mode), the vehicle is driven not at the third fixed shift mode but at the fifth fixed shift mode. Therefore, sudden speed reduction of the vehicle can be prevented. Further, after the vehicle is stopped, when the pressure of the clutch C2 is reduced by shifting from D-range to N-range, P-range, and R-range, and by turning off the ignition switch, the latch of the shift valve SV1 is released. Therefore, the vehicle can be restarted at the third shift stage. Further, when the ON/OFF solenoid valve S2 can be at the ON-state (∘), the vehicle can be started at the first shift stage.
[D-range 6thth Fixed Shift Mode]
Because the ON/OFF solenoid valve S2 is at the OFF-state (×), the D pressure transmitted through the third bottom switching circuit of the shift valve SV3 and the third bottom switching circuit of the shift valve SV2 is interrupted at the second bottom switching circuit of the shift valve SV2 and is not reached to the supply port of the linear solenoid valve SL3. Further, the D pressure is interrupted at the first top switching circuit of the shift valve SV2 and at the first top switching circuit of the shift valve SV1 and is not reached to the supply port of the linear solenoid valve SL1, the exhaust port of the linear solenoid valve SL1, and the brake B2S. Accordingly, the clutch C2 (SL2) and the brake B1 (SL4) are engaged and the sixth shift stage is thereby established.
[R-range]
When the R-range is selected, the R pressure from the manual valve (not shown) is transmitted through the shuttle valve (i.e., the check ball valve) and is supplied to the brakes B2S and B2L. Further, because the ON/OFF solenoid valve S1 is at the OFF-state (×), and the ON/OFF solenoid valve S2 is at the ON-state (∘), the R pressure transmitted through the second top switching circuit of the shift valve SV1 and the second bottom switching circuit of the shift valve SV2 is supplied to the supply port of the linear solenoid valve SL3.
According to the first embodiment of the present invention, the R pressure is transmitted to an end of the shift valve SV2 for forcibly move the shift valve SV2 to the ON-side (∘) as illustrated in
According to the first embodiment of the present invention, reliability of a hold back control at the R-range is improved. Generally, in the hold back control, a reverse inhibitor is performed by turning on the linear solenoid valve SL3 and releasing the clutch C3 in order to prevent the vehicle from shifting to a reverse driving mode in a condition where the vehicle drives equal to or faster than a predetermined speed. According to the first embodiment of the present invention, even in the event that the ON-failure occurs to the linear solenoid valve SL3, transmission of the R pressure to the supply port of the linear solenoid valve SL3 can reliably be interrupted at the second top switching circuit of the shift valve SV1 as long as the ON/OFF solenoid valve S1 is at the ON-state (∘). Accordingly, the reverse inhibitor can reliably be performed when the shift mode is changed to the R-range from the first shift stage, in which the ON/OFF solenoid valves S1, S2, S3 are controlled at the OFF-, ON-, OFF-states (×∘×), from the 1-2 automatic shift mode in which the solenoid valves S1, S2, S3 are controlled at the OFF-, ON-, ON-states (×∘∘), or from the 2-6 automatic shift mode, in which the solenoid valves S1, S2, S3 are controlled at the ON -, ON-, ON-states (∘∘∘).
According to the embodiment of the present invention, an oil pressure switch SW is respectively provided at an oil passage to the clutch C1 and an oil passage to the brake B1. In the event that the ON-failure occurs to the linear solenoid valve SL2 because of the disconnection state, or the like, at the first to second shift mode at the D-range the, if the first shift stage is established in which the clutch C1 (SL1) and the brake B2 (SL2) are engaged, the shift stage may be remained at the first shift stage. In contrast, if the second shift stage is established in the aforementioned condition, the interlock may be generated due to an engagement of the clutch C1 (SL1), the brake B1 (SL4), and the brake B2 (SL2). On this occasion, the oil pressure switch SW detects the condition of the oil passage and the shift stage can be returned to the first shift stage.
Likewise, in the event that the ON-failure occurs to the linear solenoid valve SL4 because of the disconnection state, or the like, at the first to second shift mode at the D-range, the similar phenomenon as described above may be generated. However, the oil pressure switch SW detects the condition of the oil passage and the shift stage can be remained at or returned to the second shift stage.
According to the first embodiment of the present invention, measures to a secondary failure of the ON/OFF solenoid valve is prepared, the secondary failure of the ON/OFF solenoid valve being generated after the shift pattern is shifted to the fixed shift mode at the D-range due to a primary failure of the ON/OFF solenoid valve. Even in the event that the ON-failure occurs to one or two of the ON/OFF solenoid valves S1, S2, and S3, or one or two of the ON/OFF solenoid valves S1, S2, and S3 is disconnected, the shift stage can be remained or the sudden speed reduction of the vehicle can be prevented by operating the third ON/OFF solenoid valve. Further, if the third failure of the ON/OFF solenoid valve is generated, the sudden speed reduction of the vehicle can be prevented by remaining the shift stage at the current shift stage or shifting to the N range. Accordingly, if the shift pattern can be shifted to the fixed shift mode, the first or the secondary failure, or the more, can be accessed. In consequence, the oil passage structure according to the first embodiment of the present invention is predominant from the oil passage structure using a fail-safe valve of the other company in a point that a failure mode is determined due to a malfunction of a failure valve.
With reference to
With reference to
[Early Stage Detection of The ON-failure of the Linear Solenoid Valve]
Accordingly, in the event that the ON-failure occurs to the linear solenoid valve SL2, the state of the solenoid valve S3 is immediately shifted from the ON-state to the OFF-state, without relying on a type (NL/NH) linear solenoid valve according to the first embodiment. The shift pattern is then shifted from the 1-2 automatic shift mode at the D-range to the first fixed shift mode at the D-range or from the 2-6 automatic shift mode at the D-range to the fourth fixed shift mode at the D-range. Alternatively, or in addition, an additional switching valve for interrupting the supply pressure of the linear solenoid valves SL3 and SL4 by means of the output oil pressure of the linear solenoid valve SL2 may be arranged at an upstream of the supply port of the linear solenoid valves SL3 and SL4.
As described above, according to the first embodiment of the present invention, the interlock due to the ON-failure of the linear solenoid valves SL2 and SL4 because of disconnection-state, or the like, is required to be prevented at the first to second shift mode at the D-range. Especially at the second shift stage, which is faster than the first shift stage, the interlock is required to be detected at the early stage and the shift pattern is required to be shifted to an appropriated shift pattern. However, according to the second embodiment of the present invention, to which the oil passage 201 is added and the structure of the shift valve SV3 is changed, if the ON-failure occurs to the linear solenoid valve SL2 in a condition where the vehicle is driving at the second shift stage, the output oil pressure of the linear solenoid valve SL2 is shifted to the failure range from the shift range. Further, because the shift valve SV3 is turned off, the driving pressure to the linear solenoid valve SL4 is interrupted at the second bottom switching circuit of the shift valve SV3 and a down shift operation from the second shift stage to the first shift stage is automatically performed without depending on a detection and an operation of an Electronic Control Unit (i.e., ECU).
There is a method of verifying interlocking on the basis of change in rotation monitored by the ECU in a condition where the oil pressure switch SW is broken down. However, performing the down shift operation from the second shift stage to the first shift stage as described above is more safe than performing the interlock. Further, if the down shift operation from the second shift stage to the first shift stage is implemented, a safety level is enhanced and an enough time is assured. Therefore, it is possible to shift to a safer fixed shift mode by detecting the difference between the second shift stage and the first shift stage by the ECU.
The ON-failure of the linear solenoid valve SL4 in a condition where the vehicle is driving at the first shift stage may occur soon after the down shift operation from the second shift stage to the first shift stage is performed. For example, if the output oil pressure of the linear solenoid valve SL2 is shifted from the shift range to the failure range in a condition where the down shift operation from the second shift stage to the first shift stage requires longer time than a predetermined time, the shift operation can be promoted by interrupting the supply of the driving pressure to the linear solenoid valve SL4. On this occasion, the output oil pressure may be increased close to the failure range. Therefore, the shift stage can quickly be shifted to the first shift stage relative to a method of switching the shift valve by means of the ON/OFF solenoid valve after the interlock is detected by the ECU.
As well as the first to second shift mode, detection of the interlock generated at the second through sixth shift mode is required at the early stage and at the higher shift stage than the lower shift stage. On this occasion, it is necessary to shift to the suitable shift pattern in a short period of time. According to the second embodiment of the present invention, when the ON-failure occurs to the linear solenoid valve SL2 at the higher shift stages (i.e., fourth to sixth stages), the output oil pressure of the linear solenoid valve SL2 is shifted from the shift range to the failure range and the driving pressure to the linear solenoid valves SL3 and SL4 is interrupted by means of the shift valve SV3. In consequence, the clutch C2 (SL2-ON) and the clutch C1 (SL1) are engaged to establish the fourth shift stage and the interlock can be avoided without depending on the detection and the operation of the ECU.
For example, if the ON-failure occurs to the linear solenoid valve SL1SL2 in a condition where the vehicle is driving at the fourth shift stage at the second through sixth shift mode, the shift stage is remained at the fourth shift stage. Further, if the ON-failure occurs to the linear solenoid valve SL1 SL2 in a condition where the vehicle is driving at the fifth shift stage at the second through sixth shift mode, supply of the driving pressure to the linear solenoid valve SL3 is interrupted and the shift pattern is shifted to the N range in which only the clutch C2 is engaged. In this state, the change in rotation of the driving shaft is detected. If the vehicle condition is judged that the vehicle can be driven at the fourth shift stage, the linear solenoid valve SL1 is controlled at the ON-state and down shift operation to the fourth shift stage is performed. If the vehicle condition is judged that the shift stage is required to be remained at the fifth shift stage, the ON/OFF solenoid valve S2 is controlled from the ON-state to the OFF-state to shift the shift pattern to the fifth shift stage of the fixed shift mode. Moreover, if the ON-failure occurs to the linear solenoid valve SL2 in a condition where the vehicle is driving at the sixth shift stage at the second through sixth shift mode, supply of the driving pressure to the linear solenoid valve SL3 is interrupted and the shift pattern is shifted to the N-range in which only the clutch C2 is engaged. In this state, the change in rotation is detected. If the vehicle condition is judged that the fourth shift stage is applicable, the linear solenoid valve SL1 is controlled at the ON-state and down shift operation to the fourth shift stage is performed. If the vehicle condition is judged that the fifth shift stage is applicable, the ON/OFF solenoid valve S2 is controlled from the ON-state to the OFF-state to shift the shift pattern to the fifth shift stage of the fixed shift mode. On this occasion, because the sixth shift stage cannot be remained, the downshift operation is waited until the vehicle speed is lowered if the down shift operation to the fourth shift stage or the fifth shift stage is not applicable.
In a condition where the vehicle is driving at the second shift stage at the second through sixth automatic shift mode, the clutch C1 (SL1) and the brake B1 (SL4) are engaged. Therefore, generation of the interlock is limited to the ON-failure of the linear solenoid valve SL3 or SL2. Further, in a condition where the vehicle is driving at the third shift stage at the second through sixth automatic shift mode, the clutch C1 (SL1) and the clutch C3 (SL3) are engaged. Therefore, generation of the interlock is limited to the ON-failure of the linear solenoid valve SL4 or the linear solenoid valve SL2. Even when interlocking is created during the second or third shift stage, the clutch C2 (SL2-ON) and the clutch C1 (SL1-ON) are automatically engaged due to the ON-failure of the linear solenoid valve SL2 so that the fourth shift stage is established and sudden speed reduction can be prevented.
If the ON-failure occurs to the linear solenoid valve SL3 in a condition where the vehicle is driving at the second shift stage. (downshift operation from the third shift stage to the second shift stage) and if the ON-failure occurs to the linear solenoid valve SL4 in a condition where the vehicle is driving at the third shift stage (downshift operation from the fourth shift stage to the third shift stage), the solenoid valve S2 is controlled from the ON-state to the OFF-state to establish the sixth shift stage at the fixed shift mode or the ON/OFF solenoid valve S3 is controlled from the ON-state to the OFF-state to establish the fourth shift stage at the fixed shift mode. According to the second embodiment of the present invention, even in the event that the ON-failure occurs to the ON/OFF solenoid valve, the fourth shift stage at the fixed shift mode can be established by increasing the output oil pressure of the linear solenoid valve SL2 to the failure range, as long as the shift valve SV3 is not stuck. Therefore, reliability of the failure-safe is improved relative to the first embodiment of the present invention.
[Improvement in Reliability at the R-range]
As illustrated in
As illustrated in
In contrast, with reference to
[Measures to the OFF-Failure of the Linear Solenoid Valve]
In a condition where the output oil pressure of the linear solenoid valve (SLT) is in the normal throttle range, the exhaust port of the linear solenoid valve SL2 communicates with a drain (EX) and the oil passage of the first top switching circuit of the shift valve SV3 communicates with the exhaust port of the linear solenoid valve SL3 through each switching circuit of the switching valve 211. In contrast, when the output oil pressure of the linear solenoid valve (SLT) reaches the failure range, the output oil passage provided at the third-range from the top of the shift valve SV3 (the D pressure is outputted when the ON/OFF solenoid valve S3 is turned off) communicates with the exhaust port of the linear solenoid valve SL2 through the second top switching circuit of the switching valve 211. Further, the output oil circuit provided at the first range from the top of the shift valve 2 (the D pressure is outputted when the ON/OFF solenoid valves S2 and S3 are turned off) communicates with the exhaust port of the linear solenoid valve SL3 through the first top switching circuit of the switching valve 211. Alternatively, or in addition, if the [Improvement in Reliability at the R-range] is not required, a state in which the exhaust port of the linear solenoid valve SL2 communicates with the Ex (drain) and a sate in which the exhaust port of the linear solenoid valve SL2 communicates with an output oil passage of the D pressure may be changeable by remaining only the switching circuit of the switching valve 211 provided at the first range from the bottom thereof.
An operation of the oil pressure control apparatus according to the second embodiment of the present invention at each shift pattern will individually be explained hereinafter. The same operation as described in the first embodiment is not repeatedly explained.
[R-Range]
In a condition where the output pressure of the linear solenoid valve SLT exceeds the throttle range, the vehicle can completely be brought into the N-state as shown in
Under the D-range, in a condition where the ON/OFF solenoid valve S3 is at the ON-state (∘), the operation of the oil pressure control apparatus of the second embodiment is similar to that of the first embodiment. Therefore, an operation of the oil pressure control apparatus at the 1st, 3rd, 4th, and 5th shift stages in a condition where the ON/OFF solenoid valve S3 is at the OFF-state (×)will be explained hereinafter.
[D-range 1st Fixed Shift Mode]
[D-range 3rd Fixed Shift Mode]
In contrast, the D pressure transmitted though the third top switching circuit of the shift valve SV3 is transmitted through the first top switching circuit of the shift valve SV2 and reaches the second top switching circuit of the switching valve 211. Then, the D pressure is supplied to the accumulator and the exhaust port of the linear solenoid valve SL3 in the failure mode and the output oil pressure of the linear solenoid valve SL3 becomes the D pressure. Accordingly, the clutch C1 (D pressure) and the clutch C3 (D pressure) are engaged to establish the third shift stage and the vehicle can be driven regardless of the OFF-failure of the linear solenoid valves SL1 and SL3.
[D-range 4th Fixed Shift Mode]
According to the second embodiment of the present invention, if the OFF-failure occurs to the linear solenoid valve SL1, the vehicle is brought into the N state in which only the clutch C2 is engaged. However, the present invention is not limited thereto. Alternatively, or in addition, the vehicle may be driven even in a condition where the OFF-failure occurs to the linear solenoid valve SL1 by adding a switching circuit to each shift valve for supplying the oil pressure to the exhaust port of the linear solenoid valve SL1.
[D-range 5th Fixed Shift Mode]
Further, the D pressure transmitted through the third top switching circuit of the shift valve SV3 is transmitted through the first top switching circuit of the shift valve SV2 and the second top switching circuit of the switching valve 211. Then, the D pressure is supplied to the accumulator and the exhaust port of the linear solenoid valve SL3 and the output oil pressure of the linear solenoid valve SL3 becomes the D pressure. Accordingly, in a condition where the OFF-failure occurs to the linear solenoid valve SL2 or SL3, the D pressure is supplied to the clutch C2 and the clutch C3 and the vehicle can thereby be driven at the fifth shift stage.
Accordingly, in the second embodiment of the present invention, several functions are added to the oil pressure control apparatus according to the first embodiment of the present invention. According to the second embodiment of the present invention, length of the oil passage of each electromagnetic valve and frictional engagement element is reduced and each electromagnetic valve is arranged in the vicinity of an oil opening of the frictional engagement element provided at an automatic transmission body for improving functionality. However, the present invention is not limiter thereto. Alternatively, or in addition, restriction of an arrangement of each electromagnetic valve and frictional engagement element may be eased.
Unlike in the case of the first and second embodiments, according to the third embodiment of the present invention, the linear solenoid valve is arranged at the upstream of the shift valve as illustrated in
An operation of the oil pressure control apparatus according to the third embodiment of the present invention at each shift pattern will individually be explained hereinafter. The same operation as described in the aforementioned embodiments is not repeatedly explained.
[D-rage 1st-2nd Automatic Shift Mode]
Although the output oil passage of the linear solenoid valve SL3 communicates with the second top switching circuit of the shift valve SV2, because the ON/OFF solenoid valve S1 is at the OFF-state (×), the output oil pressure is interrupted at the first bottom switching circuit of the shift valve SV1 and is not reached the clutch C3. Accordingly, the clutch C1 (SL1), the brake B1 (SL4), and the brake B2 (SL2) can be controlled. Therefore, the shift pattern for automatic shift at lower shift stages can be achieved. More specifically, the automatic shift between the first shift stage using the clutch C1 (SL1) and the brake B2 (SL2) and the second shift stage using the clutch C1 (SL1) and the brake B1 (SL4) can be performed. Further, because the linear solenoid valves SL1 and SL2 are NH type, the first shift stage is automatically established at the all-electric disconnection-state of the linear solenoid valves.
[D-range 2nd-6th Automatic Shift Mode]
J Accordingly, the clutch C1 (SL1), the clutch C2 (SL2), the clutch C3 (SL3), and the brake B1 (SL4) can be controlled and the shift pattern for the automatic shift at the middle and higher shift stages, in which the skip shift among the following shift stages:
[D-range 1st Fixed Shift Mode]
Although the output oil passage of the linear solenoid valve SL3 communicates with the second top switching circuit of the shift valve SV2, because the ON/OFF solenoid valve S1 is at the OFF-state (×), the output oil pressure is interrupted at the first bottom switching circuit of the shift valve SV1 and is not reached the clutch C3. Likewise, the output oil pressure of the linear solenoid valve SL4 is interrupted at the first bottom switching circuit of the shift valve SV3 and is not reached the brake B1.
Accordingly, the clutch C1 (SL1) and the brake B2 (SL2) are engaged and the first shift stage is established. Further, because the linear solenoid valves SL1 and SL2 are the NH type, the first shift stage is remained even when all the linear solenoid valves are disconnected. The disconnection of all solenoid valves including the ON/OFF solenoid valves and the disconnection of all the linear solenoid valves are separately considered in the embodiments of the present invention because the ON/OFF solenoid valves are frequently used in the shift operation. Not only the normal disconnection but also the OFF-failure of hardware of the ON/OFF solenoid valve may be considered as the disconnection-state. In a condition where the ignition is turned off, the disconnection of all solenoid valves including the ON/OFF solenoid valves is generated.
[D-range 2nd Fixed Shift Mode]
Although the output oil passage of the linear solenoid valve SL1 communicates with the second bottom switching circuit of the shift valve SV2, because the ON/OFF solenoid valve S3 is at the ON-state (∘), the output oil pressure is interrupted at the second bottom switching circuit of the shift valve SV3 and is not reached the clutch C3. Likewise, the output oil passage of the linear solenoid valve SL3 is interrupted at the second top switching circuit of the shift valve SV2 and is not reached the clutch C3. Accordingly, the clutch C1 (SL2) and the brake B1 (SL4) are engaged and the second shift stage is established. Further, because the linear solenoid valve SL2 is the NH type and the linear solenoid valve SL4 is the NL type, the vehicle is brought into N (C1) state at the all-electric disconnection-state of the linear solenoid valves.
[D-range 3rd Fixed Shift Mode]
On this occasion, the output oil pressure of the linear solenoid valve SL3 is interrupted at the second top switching circuit of the shift valve SV2 and is not reached the clutch C3. Likewise, the output oil pressure of the linear solenoid valve SL4 is interrupted at the first bottom switching circuit and the second bottom switching circuit of the shift valve SV3 and is not reached the brake B1. Accordingly, the clutch C3 (SL1) and the clutch C1 (SL2) are engaged and the third shift stage is established. Further, because the linear solenoid valves SL1 and SL2 are the NH type, the third shift stage is remained even when all the linear solenoid valves are disconnected.
[D-range 4th Fixed Shift Mode]
Although the oil pressure passage of the linear solenoid valve SL3 communicates with the second top switching circuit of the shift valve SV2 and the first bottom switching circuit of the shift valve SV1, the output oil pressure is interrupted at the first top switching circuit of the shift valve SV3 and is not reached the clutch C3. Likewise, the output oil passage of the linear solenoid valve SL4 is interrupted at the first bottom switching circuit and the second bottom switching circuit of the shift valve SV3 and is not reached the brake B1. Accordingly, the clutch C3 (SL1) and the clutch C2 (SL2) are engaged and the fourth shift stage is established. Further, because the linear solenoid valves SL1 and SL2 are the NH type, the fourth shift stage is remained even when the all linear solenoid valve are disconnected.
[D-range 5th Fixed Shift Mode]
The output oil passage of the linear solenoid valve SL3 is interrupted at the second top switching circuit of the shift valve SV2 and is not reached the clutch C3. Likewise, the output oil passage of the linear solenoid valve SL4 is interrupted at the first bottom switching !circuit and the second bottom switching circuit of the shift valve SV3 and is note reached the brake B1. Accordingly the clutch C3 (SL1) and the clutch C2 (SL2) are engaged and the fifth shift stage is established. Further, because the linear solenoid valves SL1 and SL2 are the NH type, the fifth shift stage is remained even when all the linear solenoid valves are disconnected.
[D-range 6th Fixed Shift Mode]
Although the output oil passage of the linear solenoid valve SL1 communicates with the second bottom switching circuit of the shift valve SV2, the output oil pressure is interrupted at the second top switching valve of the shift valve SV3 and is not reached the clutch C3. Likewise, the output oil pressure of the linear solenoid valve SL3 is interrupted at the second top switching circuit of the shift valve SV2 and is not reached the clutch C3. Accordingly the clutch C2 (SL2) and the brake B1 (SL4) are engaged and the sixth shift stage is established. Further, because the linear solenoid valve SL2 is the NH type and the linear solenoid valve SL4 is the NL type, the vehicle is brought into the N (C2) state when all the linear solenoid valves are disconnected.
Under the aforementioned D-range, the vehicle comes into the N-state when the second or the sixth fixed shift mode is selected in a condition where all the linear solenoid valves are disconnected. However, if the vehicle is driving under the second fixed shift mode, the shift pattern is transmitted to the first to second automatic shift mode, second though sixth automatic shift mode, or the third fixed shift mode. Accordingly, the vehicle can be driven at those shift stages applicable for the all-electric disconnection-state of the linear solenoid 1O valves. Likewise, if the vehicle is driving under the sixth fixed shift mode, the shift pattern is transmitted to the second through sixth automatic shift mode, fifth fixed shift mode, or the third fixed shift mode. Accordingly, the vehicle can be driven at those shift stages applicable for the all-electric disconnection-state of the linear solenoid valves.
[R-range]
Accordingly, the brake B2 (R pressure) and the clutch C3 (SL1) are engaged and the reverse shift stage is established. Further, because the linear solenoid valve SL1 is the NH type, the R-range is remained when all the linear solenoid valves are disconnected.
According to the third embodiment of the present invention, the reverse driving of the vehicle can be remained by transmitting the R pressure to the clutch C3 through the first bottom switching circuit of the shift valve SV2 and the second top switching circuit of the shift valve SV3. If the R-range is selected from, a high speed driving state in a condition where the ON-failure occurs to the linear solenoid valve SL1, transmission of the R pressure to the clutch C3 can be prevented by performing the reverse inhibitor control which controls the ON/OFF solenoid valve S3 at the ON-state (∘).
According to the third embodiment of the present invention, a structure for detecting the interlock is required in case of generation of the ON-failure of the NL type linear solenoid valve at the automatic shift mode. As well as the second embodiment of the present invention, the third embodiment of the present invention is applicable as long as the oil pressure control apparatus includes a function for detecting the ON-failure of the linear solenoid valve at the early stage. Further, the third embodiment of the present invention is applicable as long as the measures to the OFF-failure of the linear solenoid valve are prepared.
If the ON-failure occurs to the linear solenoid valve SL2 because of the disconnection-state, or the like, under the second shift stage of the first to second automatic shift mode at the D-range, in which the clutch C1 (SL1) and the brake B1 (SL4) are engaged, the interlock may be generated by means of an engagement of the clutch C1 (SL1), brake B1 (SL4), and the brake B2 (SL2). However, according to the fourth embodiment of the present invention, if the output pressure of the linear solenoid valve SL2 becomes equal to or more than the predetermined value, the apply valve is switched and the brake B1 (SL4) is forcibly released. Therefore, the vehicle can be driven at the first shift stage under the current shift pattern. Further, if the apply valve is stuck, the shift pattern can be shifted to the fixed shift mode by detecting the current state of the apply valve by means of the oil pressure switch SW, which is appropriately arranged. Therefore, the vehicle is not necessarily brought into the N-mode.
According to the fourth embodiment of the present invention, the oil pressure is supplied to the exhausted port of the linear solenoid valves SL1 and SL2 by the switching valve 211 so that the output pressure can forcibly be remained. By means of an ON/OFF operation of the switching valve 211, other solenoid valves such as SLT for controlling the throttle pressure which is not involved in the shift operation can appropriately be used. As well as the second embodiment of the present invention, when the output pressure of the electromagnetic valve reaches a predetermined failure range, the switching valve 211 is activated and supplies the oil pressure to the exhausted port of the linear solenoid valves SL1 and SL2.
According to the fourth embodiment of the present invention, because the linear solenoid valve SL2 is used only at the D-range, the linear solenoid valve SL2 supplies the D pressure. The linear solenoid valve SL1 supplies the D pressure for forward driving and sullies R pressure for reverse driving through the switching circuit of the shift valve SV2 in order to selecting the clutch C3. Accordingly, if the OFF-failure occurs to the linear solenoid valve SL1 or SL2 at each fixed shift mode, the shift stage can be remained by operating the switching valve 211. The oil pressure control apparatus according to the fourth embodiment of the present invention can be configured by adding two valves to the oil pressure control apparatus according to the third embodiment of the present invention. Therefore, the oil pressure control apparatus according to the fourth embodiment of the present invention has an advantage in manufacturing cost relative to the oil pressure control apparatus to which the oil pressure switch SW are added to appropriate positions (SL3, SL4, and SV3).
According to the fifth embodiment of the present invention, the switching circuits are added to the shift valves SV2 and SV3 of the third or fourth embodiment of the present invention as illustrated in
An operation of the oil pressure control apparatus according to the fifth embodiment of the present invention at the second fixed shift mode and the sixth fixed shift mode will be explained hereinafter. The same operation as described in the aforementioned embodiments is not repeatedly explained.
[D-range 2nd Fixed Shift Mode]
The output oil pressure of the linear solenoid valve SL3 is interrupted at the second top switching circuit of the shift valve SV2 and is not reached the clutch C3. Likewise, although the output oil passage of the linear solenoid valve SL4 communicates with the second bottom switching circuit of the shift valve SV3, the output oil pressure is interrupted at the first bottom switching circuit of the shift valve SV2 and is not reached the brake B1. Accordingly, the clutch C1 (SL2) and the brake B1 (SL1) are engaged and the second shift stage is established. Further, because the linear solenoid valves SL1 and SL2 are the NH type, the second shift stage is remained at the time of disconnection of all the linear solenoid valves.
[D-range 6th Fixed Shift Mode]
The output oil passage of the linear solenoid valve SL3 is interrupted at the second top switching circuit of the shift valve SV2 and is not reached the clutch C3. Likewise, although the output oil passage of the linear solenoid valve SL4 communicates with the second bottom switching circuit of the shift valve SV3, the output oil pressure is interrupted at the first bottom switching circuit of the shift valve SV2 and is not reached the brake B1. Accordingly, the clutch C2 (SL2) and the brake B1 (SL1) are engaged and the sixth shift stage is established. Further, because the linear solenoid valves SL1 and SL2 are the NH type, the sixth shift stage is remained at the time of disconnection of all the linear solenoid valves.
The embodiments of the present invention have been described in the foregoing specification. However the present invention is not limited thereto. An oil passage or control can be added to the aforementioned embodiments of the present invention. Alternatively or in addition, a lock-up may be performed by connecting the lock-up linear solenoid valve (not shown) only in a condition where the ON/OFF solenoid valve S3 is turned on after the shift pattern is switched to the first to second automatic shift mode. Thereby, even when the failure of the linear solenoid valve is generated at the first shift stage, sudden engine stall can be avoided.
According to the embodiments of the present invention, the oil pressure control apparatus is applicable for the automatic transmission having the five frictional engagement elements for the six forward shift stages. However, the present invention is not limited thereto and the oil pressure control apparatus may be applicable for other types of automatic transmission. According to the aforementioned embodiments of the present invention, the eight shift patterns using the three shift valves are respectively assigned to the two automatic shift modes, and each fixed shift mode. Alternatively, or in addition, if the automatic transmission includes only one automatic shift mode, the shift patterns may respectively be assigned to the one automatic shift mode, each fixed shift mode, and a backup shift mode.
In order to perform the skip shift operation among more than seven shift stages, the number of the linear solenoids for activating each frictional engagement element may be increased. The present invention is applicable for the automatic transmission capable of the skip shift operation among more than seven shift stages and the reliability of the failure-safe mechanism can be improved by increasing the shift patterns by increasing the number of the shift valves.
The automatic transmission illustrated in
As we can see from
According to the sixth embodiment of the present invention, the brake B2 includes a brake B2S, which possesses a small oil chamber of which volume varies in response to an operation of a piston, and a brake B2L, which possesses a large oil chamber of which volume varies in response to an operation of a piston. This structure is employed under a garage controlling, and yet, when a single piston type brake is required, an oil passage to the brake B2S can be omitted.
An upward arrow t in
According to this embodiment, in response to an ON operation of the solenoid valve S1, a shift pattern out of the multi shift pattern for a skip shift, the fixed shift stages of 4th, 5th and 6th can be selectively established in the transmission. In response to an OFF operation of the solenoid valve S1, other lower speed shift stage can be selectively established. Further, as described later, the shift valve SV1 is latched into an ON-side by use of an oil pressure to be supplied to the clutch C2. Therefore, even if the solenoid valve S1 malfunctions, a sudden speed reduction from a high shift stage to a low shift stage can be prevented.
As described above, the aforementioned linear solenoid valves SL1, SL2, SL3 and SL4 are all normal low-type linear solenoid valves. As described later, in case of all the linear solenoid valves being disconnected, a fixed shift stage can be established by selecting a shift valve. It is therefore possible to prevent an occurrence that an engagement element is not engaged because of a primary failure such as all disconnection. It is further possible to preclude an interlocking due to an ON-failure of a linear solenoid valve. Meanwhile, in a case of all valves including the shift valves being electrically disconnected, the solenoid valves S1, S2 and S3 are all switched off, and a fixed shift stage 3rd can be established in the transmission without operating any linear solenoid valves.
Going back to
Under a shift pattern of the fixed shift stage 1st, the clutch C1 is directly supplied with a line pressure. Therefore, even when a pressure level, which exceeds the maximum output pressure level of a linear solenoid valve, is needed, for example, at a time of a stall-starting, there is no need to provide a lock valve for introducing the line pressure, a gain switching valve and so on, which leads to a simple oil pass configuration and a manufacturing cost reduction.
Under the 1st fixed shift pattern, an oil passage is established, through which a D pressure is introduced from a first top switching circuit of the shift valve SV1 to a shuttle valve connected to the brake B2S via switching circuits of the shift valves SV2 and SV3. Therefore, the D pressure is supplied to the brake B2S, and the linear solenoid valve SL2 is connected to the brake B2L having a large area. While recent developments is leading to a torque-up in response to an increase in the number of shift stages in the transmission, a manufacturing cost reduction, and a downsizing of the transmission has been needed. According to the above structure, a 1-2 one-way clutch (O.W.C) is hence no longer needed for the transmission, which satisfies recent need. That is, even in a case where the linear solenoid valve SL2 is at an OFF-failure, it is possible to perform a vehicle start at the first shift stage by use of the clutch C1 and the brake B2S, and it is further possible to perform a coast control.
As is illustrated in
According to the above-described oil passage configuration, an oil passage, through which the R pressure is guided to a switching circuit of the shift valve SV1, and an oil passage, by which the R pressure is compulsorily urged to the shift valve SV2 and the shift valve SV2 is turned on (∘), are provided. Therefore, even if the shift valve SV1 is at the OFF-state (×), as far as the R pressure has been supplied to the shift valve SV1, the shift valve SV2 is turned on (∘) and the linear solenoid valve SL3 can engage the clutch C3 for the use of a reverse shift stage.
As described above, according to the sixth embodiment of the present invention, an oil passage length between each frictional engagement element and each solenoid valve (linear solenoid valve) can be shortened, and the solenoid valves (linear solenoid valves) can be located at appropriate positions for the positions of the frictional engagement elements in the automatic transmission.
According to an example of an entire oil circuit illustrated in
Next, described below is an operation at a time of selecting each shift pattern according to the sixth embodiment.
[D-range 1-2 Shift Mode]
Meanwhile, although there is an oil passage guiding the D pressure to the shift valve SV1 via a second bottom switching circuit of the shift valve SV3, because the shift valve SV1 is at an OFF-state (×), the D pressure is not supplied to the supply port of the linear solenoid valve SL3. The D pressure, which is to be supplied through the first top switching circuit of the shift valve SV1, is cut off by the shift valves SV2 and SV3, so that the D pressure is not supplied to the brake B2S and the exhaust port of the linear solenoid valve SL1. The output oil passage of the linear solenoid valve SL2 communicates with the brake B2L via a second bottom switching circuit of the shift valve SV1, a second bottom switching circuit of the shift valve SV2, and a shuttle valve (a check-ball valve).
As described above, the clutch C1 (the linear solenoid valve SL1), the brake B1 (the linear solenoid valve SL4) and the brake B2L (the linear solenoid valve SL2) can be controlled, and a lower shift stage automatic shift operation between the first shift stage with the clutch C1 (SL1) and the second shift stage with the brake B1 (the SL4) and the second shift stage with the brake B1 (SL4) can be executed.
[D-range 2-6 Automatic Shift Mode]
Meanwhile, although there is an oil passage for guiding the D pressure to the first top switching circuit of the shift valve SV1, this oil passage is cut off by the shift valve SV1 being at the ON-state (∘). Therefore, the D pressure does not reach the brake B2S and the exhaust port of the linear solenoid valve SL1.
As described above, the clutch C1 (SL1), the clutch C2 (SL2), the clutch C3 (SL3) and the brake B1 (SL4) can be controlled, and a middle shift stage automatic shift pattern, in which a skip shift can be performed, can be executed.
[D-range 1st Fixed Shift Mode]
Meanwhile, because the solenoid valve S3 is at the OFF-state (×), the second bottom switching circuit of the shift valve SV3 does not allow a further flow of the D pressure so that the D pressure does not reach the supply port of the linear solenoid valve SL4. Likewise, the D pressure, which traveled through the third top switching circuit of the shift valve SV3, is not allowed to further flow by a fourth bottom switching circuit of the shift valve SV2, and does not reach the supply port of the linear solenoid valve SL3.
As described above, the clutch C1 (D pressure), the brake B2S (D pressure) and the brake B2L (SL2) are engaged, and the first shift stage is established in the automatic transmission. Here, even in a case where the linear solenoid valve SL2 for operating the brake B2L is brought to an OFF-failure state, a coast control with the brake B2S can be manipulated, and even if a stall-starting is difficult to be carried out, a driving at the first shift stage can be implemented.
[D-range 2nd Fixed Shift Mode]
Meanwhile, the D pressure, which travels through the second bottom switching circuit of the shift valve SV3, is cut by the third top switching circuit of the shift valve SV1 so that the supply port of the linear solenoid valve SL3 is not supplied with the D pressure. Likewise, the D pressure, which traveled through the first top switching circuit of the shift valve SV1, reaches the second top switching circuit of the shift valve SV3. However, the D pressure is cut off by the second top switching circuit of the shift valve SV3 and is not supplied to the exhaust port of the linear solenoid valve SL1 and the brake B2S. As described above, the clutch C1 (SL1) and the brake B1 (SL4) are engaged, and the second shift stage is established in the automatic transmission.
[D-range 3rd Fixed Shift Mode]
Further, the flow of the D pressure to a supply port of the linear solenoid valve SL4 is not allowed by the second bottom switching circuit of the shift valve SV3. As described above, the clutch C1 (D pressure) and the clutch C3 (linear solenoid valve SL3) are engaged and the third shift stage is established in the automatic transmission. Therefore, a vehicle can travel not only in the event that all the linear solenoid valves are electrically disconnected but also in the event that all the valves including the solenoid valves are electrically disconnected.
[D-range 4th Fixed Shift Mode]
Further, because the solenoid valve S3 is at the OFF-state (×), the D pressure is cut off by the second bottom switching circuit of the shift valve SV3 and does not reach the supply port of the linear solenoid valve SL4. Still further, the D pressure, which travels through the third top switching circuit of the shift valve SV3, is cut off by the fourth bottom switching circuit of the shift valve SV2 and is not allowed to reach the supply port of the linear solenoid valve SL3. As described above, the clutch C1 (SL1) and the clutch C2 (SL2) are engaged, and the fourth shift stage is established in the automatic transmission.
[D-range 5th Fixed Shift Mode]
The D pressure is cut off by the second bottom switching circuit of the shift valve SV3, the first top switching circuit of the shift valve SV2 and the first top switching circuit of the shift valve SV1, respectively. The D pressure is hence not supplied to the supply port of the linear solenoid valve SL4, the supply port of the linear solenoid valve SL1, the brake B2S. Therefore, the fifth shift stage is established with the clutch C2 (SL1) and the clutch C3 (SL3) engaged. Therefore, even in the event where all the linear solenoid valves are electrically disconnected, a vehicle can move forward.
While a vehicle is traveling at a shift stage (including the sixth shift stage described later) being equal to or greater than the fourth shift stage, in which the clutch C2 is frictionally engaged, the accumulator ACC3, which is connected to the latch circuit, works for keeping the shift valve SV1 latched to the ON-side (∘). Therefore, in the case where all solenoid valves are electrically disconnected, even if the solenoid valve SV1 is switched from the ON-state (∘) to the OFF-state (×), the shift valve SV1 is kept latched at the ON-side (∘).
[D-range 6th Fixed Shift Mode]
Meanwhile, because the solenoid valve S2 is at the OFF-state (×), the D pressure, which traveled through the second bottom switching circuit of the shift valve SV3 and the fourth bottom switching circuit of the shift valve SV1, is cut off by the third bottom switching circuit of the shift valve SV2 and is not supplied to the supply port of the linear solenoid valve SL3. The D pressure is cut off by the first top switching circuit of the shift valve SV2 and the first top switching circuit of the shift valve SV1. Therefore, the D pressure does not reach the supply port of the linear solenoid valve SL1, the exhaust port of the linear solenoid valve SL1, and the brake B2S. Therefore, the clutch C2 (SL2) and the brake B1 (SL4) are engaged and the sixth shift stage is established.
The sixth embodiment of the present invention was described above. Substitution of the components by equivalents, addition of oil passages, addition of controls is applicable to this embodiment. For example, according to the sixth embodiment, the accumulator ACC3 for latching the shift valve SV1 is provided between the shift valve SV1 and the clutch C2.
However, as illustrated in
Further, it does not prevent providing a change valve against an ON-failure of the linear solenoid valve. In addition to the oil passage configuration illustrated in
Still further, according to the sixth embodiment, in order to simplify the configuration of the oil circuit, only the linear solenoid valve SL4 does not include an oil passage to be supplied with the D pressure through its exhaust port. Alternatively, the shift valve SV3 can be provided with a switching circuit communicated at the time of the solenoid valve S3 at the ON-state (∘). When the solenoid valve S2 is at the OFF-state (×) and the solenoid valve S3 is at the ON-state (∘), the D pressure is supplied to the exhaust port of the linear solenoid valve SL4 so that the brake B1 is frictionally engaged mandatorily.
Further, according to the embodiments of the present invention, totally four oil pressure switches are provided at the output sides of the linear solenoid valves, respectively. Alternatively, by detecting interlocking by means of software means on the basis of a turbine rotation or a shift stage, it is possible to abolish the above oil pressure switches.
As is obvious from
Further, in the state where the solenoid valves S1 is at the ON-state (∘) during the R range, if all the linear solenoid valves are electrically disconnected, the R range is shifted to the N range. However, a shift range is controlled at the R range by changing the solenoid valve S1 to the Off-state (×).
As described above, if an NH-type linear solenoid valve, which excels in assuring a requisite amount of oil with high precision, is used, the oil pressure circuit can be operated with an excellent failure resistance, and the number of components can be reduced.
As illustrated in
As is obvious from
With reference to
As described above, the configuration of the shift valve SV1 according to the ninth embodiment is different from that of the eighth embodiment, in which the shift valve SV1 of the ninth embodiment does not possess the first bottom switching circuit. As a result, while a vehicle is running at a low shift stage, such as the third shift stage or lower, under the 2-6 automatic shift mode at the D range, if all electric disconnection occurs and the solenoid valve S2 is operated prior to the operation of the solenoid valve SV1, there is a possibility that an actually selected shift stage is controlled not at the third shift stage but at the fifth shift stage. In other words, the configuration of the shift valve SV1 of the ninth embodiment does not cause a downshifting. It is apparent that, if a shift lever is switched from the D range to the other range, or if an ignition key is operated again, after a vehicle stop, the vehicle can drive at the third shift stage.
In the description of the ninth embodiment, it became apparent that the third shift stage is not maintained and is shifted to the fifth shift stage, if the solenoid valve S2 is operated prior to the operation of the solenoid valve S1 in the event of the all electric disconnection while a vehicle is running at the third shift stage or lower under the 2-6 automatic shift mode at the D-range. According to the tenth embodiment, it is possible to avoid the shift operation to the fifth shift stage under the aforementioned circumstance.
Further, according to the tenth embodiment, it is possible for a vehicle to drive at the fifth shift stage in the event of the OFF-failure of the linear solenoid valve SL4 and to drive at the sixth shift stage in the event of the OFF-failure of the linear solenoid valve SL3. Therefore, driving performance can be assured at the same level as the eighth embodiment.
It is also to be understood that the words used are words of description, rather than limitation, and that in actual practice various changed may be made without departing from the spirit and scope of the present invention. More particularly, it is applicable to add oil passages or controls. For example, according to the above-described embodiments, only when the solenoid valve S3 is at the ON-state (∘), a linear solenoid valve for lock-up, which is not illustrated, is connected. If the lock-up is performed after detecting a shifting to the 1-2 automatic shift mode based on a vehicle speed and so on, even if the linear solenoid valves malfunctions at the first shift stage, engine stall can be prevented immediately.
Further, according to the above embodiments, the oil pressure control apparatus is applied for an automatic transmission that establishes the forward six shift stages in combination with the five frictional engagement elements. However, the oil pressure control apparatus is applicable for other types of automatic transmissions. For example, according to the above embodiments, the eight shift patterns, which are prescribed by the third power of two (23), are configurable with three shift valves. Two of the eight shift patterns are assigned to automatic shift patterns. The other six of the eight shift patterns are assigned to fixed shift stages. Alternatively, when one of the eight shift patterns is assigned to a single automatic shift pattern, another one can be assigned to an auxiliary automatic shift pattern, or the other seven of the eight shift patterns can be seven fixed shift stages.
In order to implement a skip shift operation while a vehicle is running at the seventh shift stage or greater, the number of linear solenoid valves, which respectively actuates the frictional engagement elements, is increased. In this case, the present invention is applicable as well. Further, it is possible to enhance reliability of this apparatus against failures, by increasing the number of shift valves and shift patterns as needed.
The principles, of the preferred embodiments and mode of operation of the present invention have been described in the foregoing specification. However, the invention, which is intended to be protected, is not to be construed as limited to the particular embodiment disclosed. Further, the embodiment described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents that fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-218000 | Jul 2005 | JP | national |
| 2005-221016 | Jul 2005 | JP | national |
