Patent Application
20070080005
1. Field of the Invention
The present invention relates to a hybrid vehicle drive control system of a hybrid vehicle having an electric drive (EV) mode a hybrid drive (HEV) mode. More particularly, the present invention relates to a hybrid vehicle drive control system for starting the engine when the vehicle shifts to the HEV mode as a result of output from the engine becoming necessary while the vehicle is traveling in the EV mode.
2. Background Information
Various configurations have been proposed for hybrid vehicle drive control systems to be used in hybrid vehicles. One such hybrid drive system is presented in Japanese Laid-Open Patent Publication No. 11-082260. The hybrid vehicle drive control system presented in Japanese Laid-Open Patent Publication No. 11-082260 has a motor/generator arranged between an engine and a transmission so as to be coupled to a shaft that directs the rotation of the engine to the transmission, a first clutch operatively connecting and disconnecting the engine to and from the motor/generator, and a second clutch operatively connecting and disconnecting the motor/generator to and from the output shaft of the transmission. The second clutch is provided to replace a conventional torque converter.
A hybrid vehicle equipped with a hybrid vehicle drive control system like that just described can be put into an electric drive (EV) mode in which the vehicle travels solely by means of power from the motor/generator by disconnecting the first clutch and connecting the second clutch. Such a hybrid vehicle can also be put into a hybrid drive (HEV) mode in which the vehicle travels using power from both the engine and the motor/generator by connecting both the first clutch and the second clutch.
When the hybrid vehicle is traveling in the EV mode and it becomes necessary to use engine output, the hybrid vehicle switches from the EV mode to the HEV mode. It is necessary to start the engine during such this mode switch.
As described in Japanese Laid-Open Patent Publication No. 11-082260, for example, this switching of modes and starting of the engine are conventionally accomplished by progressively connecting the first clutch so as to establish a connection between the engine and the motor/generator. The torque transmitted by the friction of the first clutch cranks and starts the engine, thereby accomplishing the change from the EV mode to the HEV mode.
However, the engine torque fluctuates when the engine is started and a torque fluctuation also occurs when the first clutch is progressively connected. These torque fluctuations are transmitted to the drive wheels and cause shock to occur. In order to resolve the problems associated with this shock, Japanese Laid-Open Patent Publication No. 11-082260 proposes a technology whereby the second clutch is temporarily released from its connected state between the motor/generator and transmission while the engine is being started by progressively connecting the first clutch.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved hybrid vehicle drive control system. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
With the conventional technology described in Japanese Laid-Open Patent Publication No. 11-082260, while the first clutch is being progressively connected between the engine and the motor/generator in order to crank the engine, the second clutch between the motor generator and the transmission is released (disconnected). In other words, while the engine is being cranked, the second clutch severs the connection between the power sources and the drive wheels and thereby prevents torque from being transmitted to the drive wheels. As a result, there is the possibility that the output torque delivered to the drive wheels will drop to zero while the engine is being cranked and the driver will sense an absence of torque that feels odd.
The present invention is based on the idea that by reducing the connection of the second clutch to a slipping connection instead of disconnecting the second clutch completely, the torque fluctuations that occur when the engine is started by progressively connecting the first clutch can be prevented from being transmitted to the drive wheels while also resolving the problem of the output torque delivered to the drive wheels dropping to zero and causing the driver to feel an absence (loss) of torque during engine cranking. Thus, one object of the invention is to provide a hybrid vehicle engine start control device that realizes this idea in concrete form and resolves the aforementioned problem.
Another aspect of the present invention is to provide a hybrid vehicle engine start control device that can reliably resolve the aforementioned problem without being affected by variation of the relationship between the actual connection hydraulic pressure of the second clutch and a command value of the connection hydraulic pressure of the second clutch when the second clutch is connected in a slipping state while the engine is being started.
In order to achieve the aforementioned object and other objects, a hybrid vehicle drive control system in accordance with the present invention is basically provided with an engine, a motor/generator, a first clutch, a second clutch and a controller. The first clutch is arranged to change a torque transfer capacity between the engine and the motor/generator. The second clutch is arranged to change a torque transfer capacity between the motor/generator and at least one drive wheel of a hybrid vehicle. The controller is configured to selectively control the first and second clutches to switch between an electric drive mode by releasing the first clutch and engaging the second clutch, and a hybrid drive mode by engaging both the first and second clutches. The controller is further configured to execute a slip control of the second clutch when the first clutch is being connected to start the engine during a mode change from the electric drive mode to the hybrid drive mode by controlling the torque transfer capacity of the second clutch to a target drive force required by the hybrid vehicle, and by simultaneously increasing a torque of the motor/generator by an amount corresponding to a torque required to start the engine while maintaining a slipping state of the second clutch until connection of the first clutch is completed.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.
Referring now to the attached drawings which form a part of this original disclosure:
Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
Referring initially to FIGS. 1 to 3, a front engine/rear wheel drive vehicle (rear wheel drive hybrid vehicle) is illustrated in each of the Figures in which each of the hybrid vehicles is equipped with a hybrid vehicle drive control system in accordance with one preferred embodiment of the present invention. Basically, the hybrid vehicles of FIGS. 1 to 3 illustrate three examples of alternate power trains of hybrid vehicles in which the hybrid vehicle drive control system in accordance with the present invention can be applied. In these examples, each hybrid vehicle includes, among other things, an internal combustion engine 1 with a crankshaft 1a, a pair of rear drive wheels 2, an automatic transmission 3 with an input shaft 3a, a power transfer shaft 4, a motor/generator 5, a first clutch 6 and a second clutch 7. In the power train of the hybrid vehicle shown in
The motor/generator 5 is configured and arranged such that it can be used as a motor or an electric generator. The motor/generator 5 is operatively arranged between the engine 1 and the automatic transmission 3. The first clutch 6 is operatively arranged between the motor/generator 5 and the engine 1, i.e., more specifically, between the shaft 4 and the engine crankshaft 1a. The first clutch 6 is configured and arranged to selectively engage or disengage the connection between the engine 1 and the motor/generator 5. The first clutch 6 is configured and arranged such that the torque transfer capacity thereof can be changed either continuously or in a stepwise manner. For example, the first clutch 6 can be a multi-plate wet clutch configured and arranged such that its torque transfer capacity can be changed by controlling the flow rate of a hydraulic clutch fluid (hydraulic oil) and the pressure of the hydraulic clutch fluid (clutch connection hydraulic pressure) either continuously or in a stepwise fashion by a proportional solenoid.
The second clutch 7 is provided between the motor/generator 5 and the automatic transmission 3, i.e., more specifically, between the shaft 4 and the transmission input shaft 3a. The second clutch 7 is configured and arranged to selectively engage or disengage the connection between the motor/generator 5 and the automatic transmission 3. Similarly to the first clutch 6, the second clutch 7 is configured and arranged such that the torque transfer capacity thereof can be changed either continuously or in a stepwise manner. For example, the second clutch 7 can be a multi-plate wet clutch configured such that its torque transfer capacity can be changed by controlling the flow rate of a hydraulic clutch fluid (hydraulic oil) and the pressure of the hydraulic clutch fluid (clutch connection hydraulic pressure) continuously or in a stepwise fashion by a proportional solenoid.
In this embodiment of the present invention, the automatic transmission 3 is preferably a conventional automatic transmission such as one presented in pages C-9 to C-22 of the “Nissan Skyline New Model (CV35) Handbook” published by Nissan Motor Company, Ltd. More specifically, the automatic transmission 3 is configured and arranged such that a plurality of friction elements (clutches and brakes) can be selectively engaged and disengaged and the power transmission path (e.g., first gear, second gear, etc.) is determined based on the combination of the engaged and disengaged friction elements. The automatic transmission 3 is configured and arranged to transfer the rotation of the input shaft 3a to an output shaft 3b after converting the rotation at a gear ratio corresponding to the selected gear. The rotation of the output shaft 3b is distributed to the left and right rear wheels 2 by a differential gear unit 8 and thereby contributes to moving the vehicle. Of course, it will be apparent to those skilled in the art from this disclosure that the automatic transmission 3 is not limited to a step-type automatic transmission like that just described, and it is also acceptable to use a continuously variable transmission (CTV).
When the vehicle is traveling under low load/low speed conditions, such as when the vehicle is starting to move from a stopped state, the vehicle requests an electric drive (EV) mode. Under the EV mode, the power train shown in
When the vehicle is traveling at a high speed, under a large load, or under conditions in which the amount of electric power that can be extracted from the battery is small, the vehicle requests a hybrid drive (HEV) mode. Under the HEV mode, the power train is controlled such that the first clutch 6 and the second clutch 7 are both engaged and the automatic transmission 3 is in a power transmitting state. In this state, the output rotation from the engine 1 or the output rotations from both the engine 1 and the motor/generator 5 are transferred to the transmission input shaft 3a and the transmission 3 transfers the rotation of the input shaft 3a to the transmission output shaft 3b at a gear ratio corresponding to the selected gear. The rotation of the transmission output shaft 3b is then transmitted to the rear wheels 2 through the differential gear unit 8 and the vehicle moves in the HEV mode using output from both the engine 1 and the motor/generator 5 or only the engine 1.
When the vehicle is traveling in the HEV mode and the engine 1 is running at optimum fuel efficiency such that a surplus of energy is produced, the surplus energy is used to operate the motor/generator 5 as an electric generator and, thereby, convert the surplus energy into electric energy. The generated electric energy can then be stored and used later to drive the motor/generator 5 as a motor, thereby improving the fuel efficiency of the engine 1.
Although, in
Also, instead of providing a dedicated second clutch 7 in front of the automatic transmission 3 as in
The control system shown in
Generally speaking, as explained below in more detail, the present invention is configured execute a slip control of the second clutch 7 when the first clutch 6 is progressively connected so as to start the engine 1 during a mode change of the hybrid vehicle from the electric drive mode to the hybrid drive mode. The slip control of the second clutch 7 is also executed during the hybrid drive mode when the engine 1 is restarted by resuming the fuel supply after having been in a fuel cut state in which the fuel supply to the engine 1 was stopped.
The slip control of the second clutch 7 preferably includes a first control phase in which the target drive force required by the vehicle is controlled by controlling the torque of the motor/generator and the torque transfer capacity of the second clutch is controlled to a value equivalent to the target drive force. The slip control also includes a second control phase, occurring after the first control phase, in which the target drive force of the vehicle is controlled by controlling the torque transfer capacity of the second clutch and a slipping state of the second clutch is maintained by controlling the motor generator.
With a hybrid vehicle engine start control device in accordance with the present invention, the slip control of the second clutch 7 is executed when the engine I is started in connection with the vehicle switching from the electric drive mode to the hybrid drive mode and when the engine 1 is restarted by resuming the supply of fuel after having been in a fuel cut state while the vehicle is traveling in the hybrid drive mode. The slip control of the second clutch 7 enables the target drive force to be delivered to the wheels 2 in a continuous fashion while also preventing the torque fluctuation associated with starting the engine 1 from being transmitted to the drive wheels 2. As a result, shock resulting from the torque fluctuation associated with starting the engine 1 can be avoided and the driver can be prevented from experiencing the odd feeling of an absence of driving force.
Additionally, since the slip control of the second clutch 7 is contrived to have a first control phase in which the target drive force is controlled by controlling the torque of the motor/generator 5 and the torque transfer capacity of the second clutch 7 is controlled to a value equivalent to the target drive force and a second control phase in which the target drive force of the vehicle is controlled by controlling the torque transfer capacity of the second clutch 7 while the slipping state of the second clutch is maintained by controlling the motor/generator 5, the target drive force of the vehicle is not affected by variation of the relationship between the actual connection hydraulic pressure of the second clutch 7 and a command value of the connection hydraulic pressure of the second clutch 7. As a result, the actual drive force does not drop and a sudden change in torque does not occur when the second clutch 7 starts slipping. Thus, the engine 1 can be started with little shock and the previously described operational effects can be obtained in a more reliable manner.
The integrated controller 20 preferably includes a microcomputer with a hybrid power transmitting control program that controls the operations of the engine 1, the motor/generator 5, and the first and second clutches. In other words, the microcomputer of the integrated controller 20 is programmed to control the operations of the engine 1, the motor/generator 5, and the first and second clutches 6 as discussed below. The integrated controller 20 also include other conventional components such as an input interface circuit, an output interface circuit, and storage devices such as a ROM (Read Only Memory) device and a RAM (Random Access Memory) device. It will be apparent to those skilled in the art from this disclosure that the precise structure and algorithms for the integrated controller 20 can be any combination of hardware and software that will carry out the functions of the present invention. In other words, “means plus function” clauses as utilized in the specification and claims should include any structure or hardware and/or algorithm or software that can be utilized to carry out the function of the “means plus function” clause.
The integrated controller 20 operatively connected to the following sensors: an engine speed sensor 11, a motor/generator speed sensor 12, a transmission input rotational speed sensor 13, a transmission output rotational speed sensor 14, an accelerator pedal position sensor 15 and a state of charge sensor 16. The engine speed sensor 11, the motor/generator speed sensor 12, the input rotational speed sensor 13, and the output rotational speed sensor 14 are arranged as shown in FIGS. 1 to 3. The engine speed sensor 11 is configured and arranged to detect an engine speed Ne of the engine 1 and produce a signal indicative of the detected engine speed Ne that is inputted to the integrated controller 20. The motor/generator speed sensor 12 is configured and arranged to detect a rotational speed Nm of the motor/generator 5 and produce a signal indicative of the detected rotational speed Nm that is inputted to the integrated controller 20. The transmission input rotational speed sensor 13 is configured and arranged to detect a rotational speed Ni of the input shaft 3a of the automatic transmission 3 and produce a signal indicative of the detected rotational speed Ni that is inputted to the integrated controller 20. The transmission output rotational speed sensor 14 is configured and arranged to detect a rotational speed No of the output shaft 3b of the automatic transmission 3 and produce a signal indicative of the detected rotational speed No that is inputted to the integrated controller 20. The accelerator pedal position sensor 15 is configured and arranged to detect an accelerator pedal depression amount (accelerator position APO) and produce a signal indicative of the detected accelerator pedal depression amount (accelerator position APO) that is inputted to the integrated controller 20. The state of charge sensor 16 is configured and arranged to detect a state of charge SOC (usable electric power) of a battery 9 in which electric power for the motor/generator 5 is stored and produce a signal indicative of the detected state of charge SOC that is inputted to the integrated controller 20. Thus, the integrated controller 20 receives these input signals for determining the operating point of the power train.
The integrated controller 20 is configured to select a drive (operating or traveling) mode (EV mode or HEV mode) that is capable of delivering the drive force desired by the driver based on the accelerator position APO, the battery state of charge SOC, and the transmission output rotational speed No (vehicle speed VSP). Then the integrated controller 20 is configured to compute the target engine torque tTe, the target motor/generator torque tTm (target motor/generator rotational speed tNm also acceptable), the target first clutch torque transfer capacity tTc1, and the target second clutch torque transfer capacity tTc2. The target engine torque tTe is fed to the engine controller 21 and the target motor/generator torque tTm (or the target motor/generator rotational speed tNm) is fed to the motor/generator controller 22.
The engine controller 21 is configured to control the engine 1 such that the engine torque Te becomes equal to the target engine torque tTe. The motor/generator controller 22 is configured to control the motor/generator 5 through the battery 9 and an inverter 10 such that the torque Tm (or the rotational speed Nm) of the motor/generator 5 becomes equal to the target motor/generator torque tTm (or the target motor/generator rotational speed tNm).
The integrated controller 20 is configured to supply a solenoid current corresponding to the target first clutch torque transfer capacity tTc1 to a connection control solenoid (not shown) of the first clutch 6 and a solenoid current corresponding to the target second clutch torque transfer capacity tTc2 to a connection control solenoid (not shown) of the second clutch 7. In this way, the connection force (holding force) of the first clutch 6 is controlled such that the torque transfer capacity Tc1 of the first clutch 6 becomes equal to the target torque transfer capacity tTc1 and the connection force of the second clutch 7 is controlled such that the torque transfer capacity Tc2 of the second clutch 7 becomes equal to the target torque transfer capacity tTc2.
The target drive force computing section 30 uses a target drive force map such as the one shown in
The drive mode selecting section 40 uses the EV-HEV region map shown in
The target charge/discharge quantity computing section 50 shown in
The operating point command section 60 determines a final target operating point based on the accelerator position APO, the final target drive force tFo0, the target drive mode, the vehicle speed VSP, and the target charge/discharge power tP. The operating point command section 60 then calculates the target engine torque tTe, the target motor/generator torque tTm, the target solenoid current Is1 for the first clutch 6, the target torque transfer capacity tTc2 of the second clutch 7, and the target gear SHIFT, which are transient values that vary from moment to moment.
The shift control section 70 receives the target second clutch torque transfer capacity tTc2 and the target gear SHIFT and drives the corresponding solenoid valves inside the automatic transmission 3 so as to achieve the target second clutch torque transfer capacity tTc2 and the target gear SHIFT.
In the case of the automatic transmission 3 shown in
The operating point command section 60 executes the command program shown in
In step S61, the operating point command section 60 computes a transient target drive force tFo required to move from the current drive force to the final target drive force tFo0 with a prescribed response characteristic. For example, the transient target drive force tFo can be computed by passing the final target drive force tFo0 through a low pass filter having a prescribed time constant.
In step S62, using the equation (1) shown below, the operating point command section 60 calculates a target input torque tTi of the automatic transmission 3 that will be required in order to attain the transient target drive force tFo.
tTi=tFo×Rt/if/iG (1)
In this equation, the term Rt is the effective radius of the tires of the drive wheels 2, the term if is the final gear ratio, and the term iG is the gear ratio of the automatic transmission 3 as determined by the currently selected gear.
In step S63, the operating point command section 60 selects the drive mode in accordance with the target drive mode determined by the drive mode selecting section 40 shown in
In step S64, the operating point command section 60 uses a scheduled gear shift map like the example shown in
The method of calculating the target engine torque tTe in step S65 will now be explained. If the power train is in the HEV mode, first, an ideal engine torque tTe0 is calculated using the equation (2) shown below with the target input torque tTi found in step S62, the input rotational speed Ni of the automatic transmission 3, and the engine speed Ne.
tTe0=(tTi×Ni−tP)/Ne (2)
Then, a maximum engine torque Temax is found based on the engine speed Ne using a maximum engine torque map like the example shown in
If the power train is in the EV mode, then engine torque is not necessary and the target engine torque tTe is set to zero. If the drive mode is in the midst of changing, the target engine torque tTe is determined in accordance with operations described later that are for situations in which the drive mode is in the process of being changed.
The target engine torque tTe is sent to the engine controller 21 as shown in
In step S66, using the equation (3) shown below, if the power train is in the EV mode or the HEV mode, the operating point command section 60 calculates the target motor/generator torque tTm that is necessary in order to generate the target transmission input torque tTi in conjunction with the target engine torque tTe.
tTm=tTi−tTe (3)
If the drive mode is in the midst of changing, the target motor/generator torque tTm is determined in accordance with operations described later that are for situations in which the drive mode is in the process of being changed.
The target motor/generator torque tTm is sent to the motor/generator controller 22 shown in
In step S67, the operating point command section 60 determines the target torque transfer capacity tTc1 of the first clutch 6.
If the power train is in the EV mode, the operating point command section 60 sets the target torque transfer capacity tTc1 of the first clutch 6 to zero because the first clutch 6 is released. If the power train is in the HEV mode, the operating point command section 60 sets the target torque transfer capacity tTc1 of the first clutch 6 to a maximum value. If the drive mode is in the midst of changing, the target first clutch torque transfer capacity tTc1 is determined in accordance with operations described later that are for situations in which the drive mode is in the process of being changed.
The target first clutch torque transfer capacity tTc1 is converted into a target first clutch solenoid current Is1 as shown in
In step S68, the operating point command section 60 determines the target torque transfer capacity tTc2 of the second clutch 7. If the power train is in the EV mode, the operating point command section 60 sets the target second clutch torque transfer capacity tTc2 to a value evTmax equivalent to the maximum drive force of EV mode (EV second clutch maximum torque transfer capacity). If the power train is in HEV mode, the operating point command section 60 sets the target second clutch torque transfer capacity tTc2 to a maximum value. If the drive mode is in the midst of changing, the target second clutch torque transfer capacity tTc2 is determined in accordance with operations described later that are for situations in which the drive mode is in the process of being changed.
The target second clutch torque transfer capacity tTc2 is used by the shift control section 70 shown in
The mode change control used to change from the EV mode to the HEV mode and start the engine 1 in a manner according to the present invention will now be explained in more detail with reference to the mode transition diagram shown in
Basically, at a time t1 (
More specifically, if the vehicle is traveling in the EV mode and the driver increases the accelerator position APO (increases the target drive force) as shown in
Meanwhile, if the vehicle is traveling in the EV mode and, even though the accelerator position APO remains constant as shown in
A case in which the accelerator position (target drive force) increases and the mode change from the EV mode to the HEV mode starts by passing through the mode 2301b will now be explained with reference to
Therefore, the mode change control for a case in which the mode change starts by passing through the mode 2301b, i.e., the mode change control executed when there is a request to change from the EV mode to the HEV mode due to depression of the accelerator pedal, is contrived such that the mode moves to the mode 2301b and the mode change starts at the moment t1 (see
Since the engine 1 needs to be started quickly as described previously, the target first clutch torque transfer capacity tTc1 is increased as shown in
tTc1<Tmmax−tTi (4)
As described previously, in the mode 2301b, a drive force within a range that can be distributed by the second clutch 7 is generated in the EV mode and the second clutch 7 is controlled to slip as soon as possible when the drive force exceeds the range that can be distributed by the second clutch 7. Thus, in the mode 2301b, the target second clutch torque transfer capacity tTc2 is held at a value evTmax equivalent to the maximum drive force attainable in the EV mode, as shown in
When the power train is in the mode 2301b, the target engine torque tTe is set to zero as shown in
In the mode 2301b, in order to prevent the drive force of the wheels from declining due to the sliding torque (engine cranking torque) of the first clutch 6, the target motor/generator torque tTm is set to the sum of the target transmission input torque tTi required to achieve the transient target drive force tFo and a compensation amount tTc1 that compensates for the sliding torque of the first clutch 6, as shown in the equation (5) below.
tTm=tTi−tTe (5)
During the control just described, the target motor/generator tTm increases to accommodate the increase in the target transmission input torque tTi resulting from the increase in the accelerator position APO. The second clutch 7 starts to slip when the torque inputted to the second clutch 7 from the motor/generator 5 exceeds the EV second clutch maximum torque transfer capacity evTmax, which is maintained at a value equivalent to the maximum drive force attainable in EV mode.
At the moment t2 (
As the second clutch 7 starts slipping, the torque transmitted by the second clutch 7 changes gradually in either a continuous or a stepwise manner from the torque imparted by the motor/generator 5 to the torque transfer capacity Tc2 of the second clutch 7. Consequently, there are no sudden changes in the drive force and the drive force maintains a smooth, continuous trend.
In order to cause the second clutch 7 to slip while maintaining the sliding torque of the first clutch 6, the torque transfer capacity Tc2 of the second clutch 7 must be lowered into the range of drive forces that can be delivered in EV mode. Since the second clutch torque transfer capacity Tc2 is already held at a value equivalent to the maximum drive force that can be delivered in EV mode, no additional time is required to lower the hydraulic pressure used to connect the second clutch 7 to such a level that the second clutch torque transfer capacity Tc2 enters the range of drive forces that can be delivered in EV mode. As a result, the response with which the drive force is increased as a result of starting the engine is improved.
After the transition to the mode 2303 (after the moment t2), the individual components of the power train are controlled as described below in order to reduce the shock caused by drive torque fluctuation during the connection of the first clutch 6. This control starts the engine with the sliding torque of the first clutch 6 while allowing the second clutch 7 to slip.
While the second clutch 7 is slipping, the output torque of the second clutch 7 is equal to the second clutch torque transfer capacity regardless of any torque fluctuation that occurs at the input side of the second clutch 7.
In the mode 2303, the target second clutch torque transfer capacity tTc2 is determined using the equation (6) below.
tTc2=tTi (6)
The target second clutch torque transfer capacity tTc2 is increased in accordance with the increase in the transient target drive force tFo0 (target transmission input torque tTi), as shown in
In the mode 2303, the target torque transfer capacity tTc1 of the first clutch 6 is controlled to a value within the range expressed by the equation (7) below in order to keep increasing the drive force and maintain a stable slipping state of the second clutch 7.
Tc1min<tTc1<Tmmax−tTc2=Tmmax−tTi (7)
The value Tc1min is set to the engine friction value before engine ignition occurs and to zero after engine ignition occurs.
In the mode 2303, the engine 1 is being cranked and, therefore, the engine I is controlled so as to start. Also in the mode 2303, the motor/generator 5 is controlled to, for example, a target motor/generator rotational speed tNm for achieving a target slip amount dNc2 of the second clutch 7. The target motor/generator rotational speed tNm is calculated with the following equation (8).
tNm=Ni+dNc2 (8)
The rotational speed Nm of the motor/generator 5 is controlled to the target value tNm with a PI controller (proportional-integral controller).
By using PI control, the motor/generator torque tTm can be changed in accordance with the changes in clutch torque that occur during connection of the first clutch as shown in
Therefore, it is a good idea for the target motor/generator torque tTm to include a component that is contrived to compensate for the torque fluctuation of the first clutch 6 in a feed-forward manner based on the target first clutch torque transfer capacity tTc1.
When such a feed-forward compensation is employed, the torque fluctuation of the first clutch 6 can be alleviated early by the motor/generator 5. As a result, the decrease in the rotational speed of the motor/generator can be prevented from becoming large and the slip amount of the second clutch 7 can be reduced so as to suppress the generation of heat therein.
The same objective can be achieved by using a disturbance observer based on the rotational inertia system of the motor/generator 5 instead of adding a feed-forward control as described above. If any torque other than the motor/generator torque acts on the motor/generator 5, that torque is considered to be a disturbance and a disturbance estimation is executed. The motor/generator torque is revised using the disturbance estimation value so as to offset (cancel out) the disturbance.
Another method of maintaining the slippage of the second clutch 7 without using rotational speed control is to execute an open control of the motor/generator 5 such that, as indicated in the equation (9) below, the target motor/generator torque tTm is larger than the sum of the torque amount corresponding to the drive force (the torque transfer capacity tTc2 of the second clutch 7) and the sliding torque compensation amount tTc1 of the first clutch 6.
tTm>tTc2−tTc1 (9)
At the moment t3 (
Since the control just described functions to maintain stable slippage of the second clutch 7 even when the connection of the first clutch 6 is completed, sudden changes in the amount of torque transmitted by the first clutch 6 resulting from a reversal between the side of the first clutch 6 that is rotating faster and the side that is rotating slower or from completion of the connection of the first clutch 6 can be prevented from being transmitted to the automatic transmission 3. As a result, the engine I can be started without the occurrence of torque shock and heating of the second clutch 7 can be suppressed.
In the mode 2304, the individual components of the power train are controlled as explained below in order to suppress overshooting of the engine speed Ne. Also in the mode 2304, the transmission input torque Ti is the same as the second clutch torque transfer capacity tTc2 because the second clutch 7 is still slipping.
Therefore, in the mode 2304, the target second clutch torque transfer capacity tTc2 is determined as expressed in the aforementioned equation (6) and, thus, is set in accordance with the transient target drive force tFo as shown in
In the mode 2304, since the connection of the first clutch 6 has been completed as described previously, the target first clutch torque transfer capacity tTc1 is set to the maximum torque transfer capacity as shown in
Similarly to the mode 2303, in the mode 2304 the motor/generator 5 is controlled so as to achieve, for example, a target second clutch slip amount dNc2. This can be accomplished by finding a target motor/generator rotational speed tNm using the previous equation (8) and controlling the rotational speed of the motor/generator 5 such that the motor/generator rotational speed Nm becomes equal to the target value tNm, or by executing an open control of the motor/generator 5 such that, as indicated in the previous equation (9), the target motor/generator torque tTm is larger than the sum of the torque amount corresponding to the drive force (the torque transfer capacity tTc2 of the second clutch 7) and the sliding torque compensation amount tTc1 of the first clutch 6.
After the moment t3 (shown in
Since the control just described functions to maintain stable slippage of the second clutch 7 even when the connection of the first clutch 6 is completed, sudden changes in the amount of torque transmitted by the first clutch 6 resulting from a reversal between the side of the first clutch 6 that is rotating faster and the side that is rotating slower or from completion of the connection of the first clutch 6 can be prevented from being transmitted to the drive wheels 2. As a result, the engine 1 can be started without the occurrence of torque shock and heating of the second clutch 7 can be suppressed.
In the mode 2305, the torque inputted to the second clutch 7 from the engine I and motor/generator 5 and the torque transfer capacity of the second clutch 7 are controlled so as to become equal to each other in order to suppress the shock associated with reconnecting the second clutch 7. More specifically, the individual components of the power train are controlled as described below. Also in the mode 2305, the transmission input torque Ti and the second clutch torque transfer capacity tTc2 have the same value because the second clutch 7 is still slipping.
Therefore, in the mode 2305, the target second clutch torque transfer capacity tTc2 is determined as expressed in the aforementioned equation (6) and, thus, is set in accordance with the transient target drive force tFo as shown in
In the mode 2305, since the connection of the first clutch 6 has been completed as described previously, the target first clutch torque transfer capacity tTc1 is set to the maximum torque transfer capacity as shown in
In the mode 2305, the motor/generator 5 is controlled such that the second clutch 7 reaches the target slip amount dNc2 in a stable manner in order to prepare for a smooth connection of the second clutch 7 during the subsequent modes 2306 and 2307. In order to accomplish this control, a target motor/generator rotational speed tNm is calculated using the previous equation (8) and the rotational speed of the motor/generator 5 is controlled such that the motor/generator rotational speed Nm becomes equal to the target value tNm.
After the moment t4 (
The reason a prescribed amount of slippage of the second clutch 7 is targeted instead of targeting zero slippage from the start is to prevent undershooting of the rotational speed of the motor/generator 5. Undershooting of the rotational speed of the motor/generator 5 can cause the slip direction of the second clutch 7 to reverse, resulting in the occurrence of a drive force fluctuation.
The mode 2306 is contrived to maintain a state in which the torque imparted to the second clutch 7 from the engine 1 and the motor/generator 5 is substantially the same as the torque transfer capacity Tc2 of the second clutch 7 while preventing the occurrence of a drive force fluctuation resulting from overshooting the rotational speed Nm of the motor/generator 5 and causing the slip direction of the second clutch 7 to reverse. Therefore, the individual components of the power train are controlled as described below.
In the mode 2306, the transmission input torque Ti and the second clutch torque transfer capacity tTc2 have the same value because the second clutch 7 is still slipping. Therefore, in the mode 2306, the target second clutch torque transfer capacity tTc2 is determined as expressed in the aforementioned equation (6) and, thus, is set in accordance with the transient target drive force tFo as shown in
In the mode 2306, since the connection of the first clutch 6 has been completed as described previously, the target first clutch torque transfer capacity tTc1 is set to the maximum torque transfer capacity as shown in
In the mode 2306, the motor/generator 5 is controlled in such a manner that the rate of change of the target second clutch slip anount dNc2 becomes smaller as the target second clutch slip amount dNc2 decreases. In order to accomplish this control, the target second clutch slip amount dNc2 is gradually decreased to zero while a target motor/generator rotational speed tNm is calculated using the previous equation (8) and the rotational speed of the motor/generator 5 is controlled such that the motor/generator rotational speed Nm becomes equal to the target value tNm.
After the moment t5 (
By reconnecting the second clutch 7 when the target second clutch slip amount dNc2 is close to zero, the second clutch 7 is reconnected under conditions where the torque imparted to the second clutch 7 from the engine 1 and the motor/generator 5 is substantially equal to the second clutch torque transfer capacity tTc2. Consequently, a large torque fluctuation does not occur when the second clutch is reconnected, i.e., when the torque transferred by the second clutch 7 changes over from the torque transfer capacity Tc2 to the combined torque delivered by the engine 1 and the motor/generator 5.
The mode 2307 is contrived to reconnect the second clutch 7 while maintaining a state in which the torque imparted to the second clutch 7 from the engine 1 and the motor/generator 5 is substantially the same as the torque transfer capacity Tc2 of the second clutch 7. Therefore, the individual components of the power train are controlled as described below.
Due to the effects of disturbance torque and the precision of the rotational speed sensor, it can take some time for the rotational speed control of the motor/generator 5 to bring the rotational speed difference across the second clutch 7 completely to zero.
Therefore, in the mode 2307, when the slip amount of the second clutch 7 becomes somewhat close to zero, the target torque transfer capacity tTc2 of the second clutch 7 is gradually increased using an open control in such a manner that an allowable drive force fluctuation is not exceeded, as shown in
In the mode 2307, since the connection of the first clutch 6 has been completed, the target first clutch torque transfer capacity tTc1 is set to the maximum torque transfer capacity as shown in
In the mode 2307, the target engine torque tTe is set to a target engine torque in accordance with the HEV mode because the first clutch 6 is connected and the engine has been started.
As shown in
At a moment t7 when a prescribed amount of time has elapsed since the moment t6 (see
By controlling the power train as described in the preceding explanation, the second clutch 7 can be reconnected in a smooth manner without the occurrence of shock and the a mode change from the EV mode to the HEV mode that includes starting the engine 1 can be completed.
When rotational speed control of the motor/generator 5 is used to make the torque imparted to the second clutch 7 from the engine 1 and the motor/generator 5 and the second clutch torque transfer capacity Tc2 substantially equal to each other, the discrepancy between the target engine torque tTe and the actual engine torque Te and any disturbance torques are compensated for with the motor generator torque. Consequently, when the mode 2307 ends at the time t7, a difference ATm (see
Thus, if the target motor/generator torque tTm is set immediately to a target motor/generator torque in accordance with the HEV mode when the moment t7 for entering the HEV mode reached, the drive force will change based on the motor/generator torque differential ΔTm and shock will occur. Conversely, if the motor/generator torque differential ΔTm is allowed to continue, it will inhibited the ability of the vehicle to obtain the desired charge or discharge amount from the motor/generator 5. Therefore, starting from the moment t7 of
A case in which the battery state of charge SOC declines or the vehicle speed rises and the mode change from the EV mode to the HEV mode starts by passing through the mode 2301a will now be explained with reference to
Therefore, the mode change control for a case in which the mode change starts by passing through the mode 2301 a, i.e., the mode change control executed when there is a request to change from the EV mode to the HEV mode due a decline in the battery state of charge SOC or an increase in the vehicle speed, is contrived such that the mode moves to the mode 2301a and the mode change starts at the moment t1 (see
Since it is more important to start the engine 1 smoothly than to start the engine 1 with a high response speed, the mode 2301a is contrived not to start cranking the engine 1 with sliding torque of the first clutch 6.
the mode 2301a, the operating hydraulic pressure (connection hydraulic pressure) of the second clutch 7 is lowered in such a fashion that the target second clutch torque transfer capacity tTc2 is lowered to a value slightly larger than the input torque tTi of the automatic transmission 3 as shown in
In the mode 2301a, the target engine torque tTe is set to 0 as shown in
The integrated controller 20 moves from the mode 2301a to the mode 2302a (2302a1 or 2302a2) at the moment t2′ (
The mode 2302a1 is selected when the hydraulic fluid temperature is high and the controllability of the clutch hydraulic fluid pressure is good. Therefore, the individual components of the power train are controlled as described below.
In the mode 2302a1, connection control of the second clutch 7 is executed such that the second clutch 7 slips at a second clutch target slip amount dNc2. It is good to use a PI controller as a slip control device.
Since smooth starting of the engine 1 is given priority over fast response, cranking of the engine 1 by means of progressively connecting the first clutch 6 is not started in the mode 2302a1, as shown in
In the mode 2302a1, the target engine torque tTe is set to zero as shown in
In the mode 2302a1, the target motor/generator torque tTm is set to a value in accordance with the EV mode because the vehicle is still traveling in the EV mode.
Meanwhile, the mode 2302a2 is selected when the hydraulic fluid temperature is low and the controllability of the clutch hydraulic fluid pressure is poor. Since it is difficult to control the second clutch 7 such that it slips in a stable manner when the hydraulic fluid temperature is low, the individual components of the power train are controlled as described below using an open control method (which is different from the control used when the hydraulic fluid temperature is high).
In the mode 2302a2, the target second clutch torque transfer capacity tTc2 is lowered gradually at a prescribed rate of change using an open control.
Since it is more important to start the engine 1 smoothly than to start the engine 1 with a high response speed, the mode 2302a2 is contrived not to start cranking the engine 1 with sliding torque of the first clutch 6.
In the mode 2302a2, the target engine torque tTe is set to zero (0) as shown in
In the mode 2302a2, the target motor/generator torque tTm is set to a target motor/generator torque in accordance with the EV mode because the engine 1 has not been started yet and the vehicle is still traveling in the EV mode.
If the integrated controller 20 has been operating in the mode 2301a1 since the moment t2′ (
With this control, the second clutch torque transfer capacity Tc2 is controlled to be equal to the torque transmitted by the second clutch 7 when it was still connected (not slipping) and the slippage of the second clutch 7 is held at a fixed amount in a stable manner. Since the transmission input torque Ti is substantially the same both before and after the second clutch 7 starts slipping, fluctuation of the drive force can be suppressed and any resulting shock can be alleviated. The reason for this will now be explained.
If the second clutch 7 is assumed to be connected and the transmission input rotational speed Ni is assumed to be accelerating at a rate of acceleration dN, the motion of the motor/generator 5 can be expressed with the rotational motion equation shown below.
Jm×dN=Tm−Tc2 (10)
In the equation, Jm is the moment of inertia of the motor/generator 5, Tm is the motor/generator torque, and Tc2 is the torque transfer capacity of the second clutch 7. Thus, the second clutch torque transfer capacity tTc2 can be expressed as shown below based on the equation (10).
Tc2=Tm−Jm×dN (11)
Even when the second clutch 7 is slipping in a constant and stable manner, the acceleration of the motor/generator 5 is dN, just as it is when the second clutch 7 is connected. Therefore, the rotation motion of the motor/generator 5 can still be expressed according to the rotational motion equation (10). Likewise, the torque transfer capacity Tc2 of the second clutch 7 can be expressed with the same equation (11) as when the second clutch 7 is connected. As a result, when the second clutch 7 is slipping in a constant and stable manner, the torque transfer capacity of the second clutch can be automatically adjusted to be the same as the torque that was transferred when the second clutch was connected.
After the integrated controller 20 moves from the mode 2302a (mode 2302a1 or 2302a2) to the mode 2302 at the moment t2 (
When the second clutch 7 starts to slip, the torque transfer capacity Tc2 of the second clutch 7 is approximately the same as the transmission input torque Ti. However, since the clutch hydraulic pressure (connection hydraulic pressure) lags behind the target value, target second clutch torque transfer capacity tTc2 is slightly smaller than the transmission input torque Ti at the point in time when the second clutch 7 starts to slip. Furthermore, when the clutch hydraulic pressure stabilizes, the torque transfer capacity Tc2 of the second clutch 7 is slightly smaller than when the second clutch 7 first started to slip and the drive force is smaller, too. Therefore, instead of using the start of slippage of the second clutch 7 alone as the condition for moving to the mode 2303, the integrated controller 20 waits until a prescribed amount of time required for the slippage to stabilize has elapsed since the second clutch 7 started to slip. By controlling the mode progression in this way, a sudden change in drive force accompanying the start of slippage of the second clutch 7 can be avoided even when the temperature of the clutch hydraulic fluid is low and the controllability of the clutch hydraulic pressure is poor. Thus, the control precision under low temperature conditions can be improved.
In a case in which the mode 2032a2 will be passed through, the control is executed in such a fashion that the time period from the moment t1 when the mode 2031 a starts to the moment t2 when the mode 2303 starts is shorter when the accelerator position APO is larger. Additionally, the rate at which the target second clutch torque transfer capacity tTc2 is decreased (rate at which the connection hydraulic pressure of the second clutch 7 is decreased) by means of the open control executed during the mode 2032a2 can be increased.
With a hybrid vehicle engine start control device in accordance with this embodiment, during a switch from the EV mode to the HEV mode, slip control of the second clutch 7 is executed when the engine 1 is started by progressively connecting the first clutch 6. The slip control of the second clutch 7 enables the drive force to be delivered to the wheels 2 in a continuous fashion while also preventing the torque fluctuation associated with starting the engine 1 from being transmitted to the drive wheels 2. As a result, shock resulting from the torque fluctuation associated with starting the engine 1 can be avoided and the driver can be prevented from experiencing the odd feeling of an absence of driving force.
Additionally, the slip control of the second clutch 7 is contrived to have a first control phase comprising the mode 2301b (modes 2301a, 2302a1, and 2302a2) in which the drive force is controlled by controlling the torque (tTm) of the motor/generator 5 and the torque transfer capacity tTc2 of the second clutch 7 is controlled to a value equivalent to the drive force and a second control phase comprising the next mode 2303 in which the drive force of the vehicle is controlled by controlling the torque transfer capacity (tTc2) of the second clutch 7 while a slipping state dNc2 of the second clutch 7 is maintained by controlling the motor/generator 5. Consequently, the drive force of the vehicle is not affected by variation of the relationship between the actual connection hydraulic pressure of the second clutch 7 and a command value of the connection hydraulic pressure of the second clutch 7. As a result, the drive force does not drop and a sudden change in torque does not occur when the second clutch 7 starts slipping. Thus, the engine 1 can be started with little shock and the previously described operational effects can be obtained in a more reliable manner.
Also, since the control is contrived such that the engine 1 is started after the second control phase has been entered, the torque fluctuation associated with starting the engine is not involved in the control of the torque transfer capacity of the second clutch 7 during the first control phase. As a result, during the first control phase, the drive force can be controlled in accordance with the EV mode with good precision even though the torque transfer capacity of the second clutch 7 is being controlled to a value equivalent to the drive force.
Preferably, the controller is further configured to control the torque transfer capacity of the second clutch 7, in the first control phase, to a value equivalent to the target drive force by executing a rotational differential servo control of the second clutch 7 that uses feedback control of the difference between the input and output rotational speeds of the clutch 7. Since the torque transfer capacity tTc2 of the second clutch 7 is controlled to a value equivalent to the drive force by using a rotation differential servo control of the second clutch 7 during the first control phase, the torque transfer capacity tTc2 of the second clutch 7 is automatically adjusted to a value equivalent to the drive force and can be controlled to the value equivalent to the drive force with good precision.
The control can be contrived such that in the first control phase the connection hydraulic pressure of the second clutch 7 is decreased from a hydraulic pressure range in which the second clutch 7 does not slip until the second clutch 7 starts to slip and the connection hydraulic pressure at which the second clutch 7 starts to slip is set as a hydraulic pressure value equivalent to the target drive force, and such that the control shifts to the second control phase when the second clutch 7 starts to slip. In such a case, the connection hydraulic pressure of the second clutch 7 can be set in a stable manner to a value that is nearly equivalent to the target drive force even when the controllability of the hydraulic pressure is poor and good performance cannot be obtained from the second clutch rotation differential servo system.
The control can also be contrived such that an actual connection hydraulic pressure of the second clutch 7 that is estimated based on a command value of the connection hydraulic pressure of the second clutch 7 and an estimated response of the actual hydraulic pressure with respect to the command value of the connection hydraulic pressure of the second clutch 7 is used as the connection hydraulic pressure of the second clutch 7 at which the second clutch 7 starts to slip and the first control phase ends. In such a case, the connection hydraulic pressure of the second clutch 7 can be set with a high degree of precision to a value that is nearly equivalent to the target drive force even when the controllability of the hydraulic pressure is poor and good performance cannot be obtained from the second clutch rotation differential servo system.
The control can also be contrived such that, in the second control phase, the connection hydraulic pressure of the second clutch 7 is adjusted (increased or decreased) in accordance with an increase or decrease of the target drive force relative to an initial value of the connection hydraulic pressure of the second clutch 7 using a relationship between the target drive force and the connection hydraulic pressure of the second clutch 7 at the point in time when the first control phase ended as a reference. In such a case, the drive force can be controlled with a high degree of precision without being affected by the torque fluctuation accompanying the starting of the engine 1.
Furthermore, in the first control phase, the control of the torque transfer capacity of the second clutch 7 to a value equivalent to the drive force required by the vehicle is accomplished by executing a rotation differential servo control of the second clutch 7 in the mode 2302a1 when the temperature of the clutch hydraulic fluid is within a prescribed region and by executing a connection hydraulic pressure control whereby the connection hydraulic pressure of the second clutch 7 is gradually lowered from a hydraulic pressure range in which the second clutch 7 does not slip when the temperature of the clutch hydraulic fluid is outside said prescribed region. Consequently, when the connection hydraulic pressure of the second clutch 7 is reduced in order to adjust the torque transfer capacity tTc2 of the second clutch 7 to a value equivalent to the drive force during the first control phase, the hydraulic fluid pressure can be controlled in a manner that is well suited to the controllability of the hydraulic fluid pressure so as to achieve the best control results possible in view of the controllability of the hydraulic fluid pressure.
When the length of the first control phase is controlled so as to become shorter as the accelerator pedal depression amount (accelerator position APO) increases, the power train can accommodate the higher drive force response that is required when the accelerator position APO is larger. When the first control phase is shortened, the precision with which the clutch connection hydraulic pressure is adjusted declines and the drive force deviates farther from the target value. However, since the accelerator position APO is large, the change in the drive force is also large and it is difficult for the driver to feel the deviation of the drive force. Consequently, the driver does not feel any obvious drive force shock due to the aforementioned deviation and the response with which the drive force changes can be improved without increasing the degree of physically perceivable drive force shock.
The first control phase can be omitted in situations where the vehicle changes to the HEV mode due to the accelerator pedal being depressed while the vehicle is traveling in the EV mode. Although omitting the first control phase causes the variation of the drive force to increase, the response with which drive force changes is improved and the drive force response that is required when the vehicle is being accelerator by depressing the accelerator pedal can be realized by giving priority to improving the drive force response over preventing shock caused by drive force variation.
Although in the preceding embodiments the concept of the present invention is applied to cases in which the engine is started in connection with changing from the EV mode to the HEV mode, the present invention can also be applied when the engine is started in connection with a control other than a mode change control. For example, the present invention can be applied to a fuel cut recovery control in which the engine is started in connection with resuming the fuel supply after the vehicle has been in a fuel cut state in which the fuel supply to the engine was stopped. A fuel cut state is one example of a state in which the vehicle is traveling in an EV mode and the concept of the present invention can be readily applied in situations where it is necessary to alleviate shock resulting from torque fluctuation associated with starting the engine during a fuel recovery control (a change from a fuel cut state in which the engine is stopped to a state in which fuel is supplied to the engine and the engine is running). When the present invention is applied to a fuel recover control, the same operational effects can be obtained as when the invention is applied to a mode change control.
In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. Also as used herein to describe the above embodiment(s), the following directional terms “forward, rearward, above, downward, vertical, horizontal, below and transverse” as well as any other similar directional terms refer to those directions of a vehicle equipped with the present invention. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a vehicle equipped with the present invention. The term “detect” as used herein to describe an operation or function carried out by a component, a section, a device or the like includes a component, a section, a device or the like that does not require physical detection, but rather includes determining, measuring, modeling, predicting or computing or the like to carry out the operation or function. The term “configured” as used herein to describe a component, section or part of a device includes hardware and/or software that is constructed and/or programmed to carry out the desired function. Moreover, terms that are expressed as “means-plus function” in the claims should include any structure that can be utilized to carry out the function of that part of the present invention. The terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.
While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-293248 | Oct 2005 | JP | national |
This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2005-293248 filed on Oct. 6, 2005. The entire disclosure of Japanese Patent Application No. 2005-293248 is hereby incorporated herein by reference.
