Patent Application
20200141484
The disclosure of Japanese Patent Application No. 2018-210070 filed on Nov. 7, 2018 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The disclosure relates to a hydraulic control system and a control method therefor.
Japanese Unexamined Patent Application Publication No. 2009-115267 (JP 2009-115267 A) describes a hydraulic control system including an upper valve body, a lower valve body, and a valve body plate. The valve body plate is provided between the upper valve body and the lower valve body, and includes holes that connect a fluid passage of the upper valve body and fluid passages of the lower valve body.
However, when the difference between the upstream-side pressure and downstream-side pressure of any of the holes provided in the valve body plate is large, the flow rate of hydraulic fluid passing through the hole increases, causing an increase in negative pressure. Thus, cavitation may occur inside the hole. When such cavitation occurs, high-frequency noise may occur.
The disclosure provides a hydraulic control system and a control method therefor, which are able to reduce occurrence of high-frequency noise.
A first aspect of the disclosure provides a hydraulic control system. The hydraulic control system includes an upper valve body, a lower valve body, a valve body plate provided between the upper valve body and the lower valve body, the valve body plate including a hole connecting a fluid passage of the upper valve body and a fluid passage of the lower valve body, a solenoid valve configured to control a pressure upstream of the hole, and an electronic control unit. The electronic control unit is configured to, when the electronic control unit determines that a vehicle on which the hydraulic control system is mounted is stopped, decrease the pressure upstream of the hole by controlling the solenoid valve.
With the hydraulic control system of the above aspect, hydraulic control for reducing occurrence of cavitation can be performed with the solenoid valve that is not affected in a stopped state of the vehicle.
In the above aspect, the hydraulic control system may include a plurality of the solenoid valves, the solenoid valves may be used to control an engaging pressure of an engagement element of a hydraulic frictional engagement device, and the solenoid valves may includes an engagement element on-off solenoid valve and a lockup on-off solenoid valve. The engagement element on-off solenoid valve may be configured to output a switching fluid pressure by using a modulator fluid pressure as a source pressure. The lockup on-off solenoid valve may be used to control an engaging pressure of a lockup clutch of a torque converter, and the lockup on-off solenoid valve may be configured to output a switching fluid pressure by using the modulator fluid pressure as a source pressure.
In the above aspect, the hydraulic frictional engagement device may be a forward-reverse switching device including a forward engagement element and a reverse engagement element, the forward engagement element may be provided in a path that transmits rotation in a direction to cause forward movement of the vehicle when the forward engagement element is engaged, the reverse engagement element may be provided in a path that transmits rotation in a direction to cause reverse movement of the vehicle when the reverse engagement element is engaged. The electronic control unit may be configured to, when the electronic control unit determines that the vehicle is stopped, place the engagement element on-off solenoid valve and the lockup on-off solenoid valve in an off position.
With the above configuration, normally, both the engagement element on-off solenoid valve and the lockup on-off solenoid valve that can be placed in an on position in preparation for a start of movement after a stop of the vehicle are placed in the off position, so occurrence of cavitation in a vehicle stopped state is reduced.
A second aspect of the disclosure provides a control method for a hydraulic control system. The hydraulic control system includes an upper valve body, a lower valve body, a valve body plate provided between the upper valve body and the lower valve body, the valve body plate including a hole connecting a fluid passage of the upper valve body and a fluid passage of the lower valve body, and a solenoid valve configured to control a pressure upstream of the hole. The control method includes decreasing the pressure upstream of the hole by controlling the solenoid valve, when it is determined that a vehicle on which the hydraulic control system is mounted is stopped.
With the control method for a hydraulic control system according to the above aspect, hydraulic control for reducing occurrence of cavitation can be performed with the solenoid valve that is not affected in a stopped state of the vehicle.
The hydraulic control system and control method therefor according to the aspects of the disclosure are advantageous in that, when it is determined that the vehicle is stopped, the pressure upstream of the hole of the valve body plate is decreased with the solenoid valve, with the result that no cavitation occurs, and, in a situation that high-frequency noise can be remarkable, generation of high-frequency noise is reduced by reducing the difference between the upstream-side pressure and downstream-side pressure of the hole.
Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
Hereinafter, an embodiment of a hydraulic control system according to the disclosure will be described. The present embodiment does not limit the disclosure.
The torque converter 14 includes a pump impeller 14p and a turbine runner 14t. The pump impeller 14p is coupled to a crankshaft 13 of the engine 12. The turbine runner 14t is coupled to the forward-reverse switching device 16 via a turbine shaft 30. The turbine shaft 30 may be regarded as an output-side member of the torque converter 14. The torque converter 14 transmits power via fluid. A lockup clutch 26 is provided between the pump impeller 14p and the turbine runner 14t. The lockup clutch 26 is engaged or disengaged when hydraulic pressures respectively supplied to an engaging-side fluid chamber and a disengaging-side fluid chamber are switched by a lockup control valve (that is, a lockup on-off solenoid valve) (not shown) in a hydraulic control circuit 100. When the lockup clutch 26 is completely engaged, the pump impeller 14p and the turbine runner 14t are integrally rotated. A mechanical oil pump 28 is coupled to the pump impeller 14p. The mechanical oil pump 28 generates hydraulic fluid pressure when driven by the engine 12 for rotation. The hydraulic fluid pressure is a fluid pressure for controlling a speed shift of the continuously variable transmission 18, generating a belt clamping force in the continuously variable transmission 18, controlling the torque capacity of the lockup clutch 26, switching the power transmission path in the forward-reverse switching device 16, or supplying lubricating oil to various portions of the power transmission path of the vehicle 10.
The forward-reverse switching device 16 is mainly made up of a forward clutch C1, a reverse brake B1, and a double-pinion planetary gear unit 16p. The turbine shaft 30 of the torque converter 14 is integrally coupled to a sun gear 16s. An input shaft 32 of the continuously variable transmission 18 is integrally coupled to a carrier 16c. The carrier 16c and the sun gear 16s are selectively coupled to each other via the forward clutch C1. A ring gear 16r is selectively fixed to a housing 34 via the reverse brake B1. The housing 34 serves as a non-rotating member. The forward clutch C1 and the reverse brake B1 each may be regarded as a connect-disconnect device. Each of the forward clutch C1 and the reverse brake B1 is a hydraulic frictional engagement device that is frictionally engaged by a hydraulic cylinder.
In the thus configured forward-reverse switching device 16, when the forward clutch C1 is engaged and the reverse brake B1 is disengaged, the forward-reverse switching device 16 is placed in an integrally rotatable state. As a result, the turbine shaft 30 is directly coupled to the input shaft 32, a forward power transmission path is established (achieved). Thus, driving force in a direction to cause forward movement is transmitted to the continuously variable transmission 18 side. When the reverse brake B1 is engaged and the forward clutch C1 is disengaged, a reverse power transmission path is established (achieved) in the forward-reverse switching device 16. As a result, the input shaft 32 is rotated in a reverse direction to the rotation direction of the turbine shaft 30. Thus, driving force in a direction to cause reverse movement is transmitted to the continuously variable transmission 18 side. When both the forward clutch C1 and the reverse brake B1 are disengaged, the forward-reverse switching device 16 is placed in a neutral state (transmission interrupted state) where transmission of power is interrupted.
The engine 12 is, for example, an internal combustion engine, such as a gasoline engine and a diesel engine. An electronic throttle valve 40 is provided in an intake pipe 36 of the engine 12. The electronic throttle valve 40 is used to electrically control the intake air volume QAIR of the engine 12 by using a throttle actuator 38.
The continuously variable transmission 18 includes a primary pulley 42, a secondary pulley 46, and a transmission belt 48. Power is transmitted via frictional force between the transmission belt 48 and each of the primary pulley 42 and the secondary pulley 46. The primary pulley 42 is an input-side member provided on the input shaft 32, and has a variable effective diameter. The secondary pulley 46 is an output-side member provided on an output shaft 44, and has a variable effective diameter. The transmission belt 48 is wound around the primary pulley 42 and the secondary pulley 46.
The primary pulley 42 includes a fixed sheave 42a, a movable sheave 42b, and a primary hydraulic cylinder 42c. The fixed sheave 42a serves as an input-side fixed rotating body fixed to the input shaft 32. The movable sheave 42b serves as an input-side movable rotating body provided so as to be relatively non-rotatable about an axis and movable in a direction of the axis with respect to the input shaft 32. The primary hydraulic cylinder 42c serves as a hydraulic actuator that applies primary thrust Win (=Primary pressure Pin×Pressure receiving area of the movable sheave 42b) in the primary pulley 42 for changing the V-groove width between the fixed sheave 42a and the movable sheave 42b. The secondary pulley 46 includes a fixed rotating body (fixed sheave) 46a, a movable sheave 46b, and a secondary hydraulic cylinder 46c. The fixed sheave 46a serves as an output-side fixed rotating body fixed to the output shaft 44. The movable sheave 46b serves as an output-side movable rotating body provided so as to be relatively non-rotatable about an axis and movable in a direction of the axis with respect to the output shaft 44. The secondary hydraulic cylinder 46c serves as a hydraulic actuator that applies secondary thrust Wout (=Secondary pressure Pout×Pressure receiving area of the movable sheave 46b) in the secondary pulley 46 for changing the V-groove width between the fixed sheave 46a and the movable sheave 46b.
The input-side pressure that is applied to the primary pulley 42, that is, the primary pressure Pin that is a fluid pressure that is applied to a fluid chamber in the primary hydraulic cylinder 42c, and the output-side pressure that is applied to the secondary pulley 46, that is, the secondary pressure Pout that is a fluid pressure that is applied to a fluid chamber in the secondary hydraulic cylinder 46c, each are independently regulated and controlled by the hydraulic control circuit 100. Thus, each of the primary thrust Win and the secondary thrust Wout is directly or indirectly controlled. As a result, the V-groove width of the primary pulley 42 and the V-groove width of the secondary pulley 46 vary, and the winding diameters (effective diameters) of the transmission belt 48 are changed. At the same time, a speed ratio γ (=Input shaft rotation speed NIN/Output shaft rotation speed NOUT) is continuously varied, and frictional force (belt clamping force) between the transmission belt 48 and each of the primary pulley 42 and the secondary pulley 46 is controlled such that the transmission belt 48 does not slip. In this way, since each of the primary pressure Pin and the secondary pressure Pout is controlled, an actual speed ratio γ is brought to a target speed ratio γ* while a slip of the transmission belt 48 is minimized. The input shaft rotation speed NIN is the rotation speed of the input shaft 32. The output shaft rotation speed NOUT is the rotation speed of the output shaft 44. In the present embodiment, as is apparent from
In the continuously variable transmission 18, for example, when the primary pressure Pin is increased, the V-groove width of the primary pulley 42 is narrowed and the speed ratio γ is reduced, that is, the continuously variable transmission 18 shifts up. When the primary pressure Pin is decreased, the V-groove width of the primary pulley 42 is widened and the speed ratio γ is increased, that is, the continuously variable transmission 18 shifts down. Therefore, when the V-groove width of the primary pulley 42 is a minimum, a minimum speed ratio γmin (maximum speed-side speed ratio, highest speed ratio) is established as the speed ratio γ of the continuously variable transmission 18. When the V-groove width of the primary pulley 42 is a maximum, a maximum speed ratio γmax (minimum speed-side speed ratio, lowest speed ratio) is established as the speed ratio γ of the continuously variable transmission 18. While a slip of the transmission belt 48 (belt slip) is minimized by the primary pressure Pin (which is synonymous with the primary thrust Win) and the secondary pressure Pout (which is synonymous with the secondary thrust Wout), a target speed ratio γ* is achieved based on the correlation between the primary thrust Win and the secondary thrust Wout. An intended shift change is not achieved by only one of the pulley pressures (which are synonymous with the thrusts).
The hydraulic control system of the vehicle 10 according to the embodiment includes the hydraulic control circuit 100 and an electronic control unit 50. The hydraulic control circuit 100 supplies hydraulic pressure to targets to be supplied with fluid pressure in the vehicle 10. The electronic control unit 50 electrically controls the hydraulic control circuit 100 or other devices.
A signal indicating a rotation angle (position) ACR of the crankshaft 13 and a rotation speed (engine rotation speed) NE of the engine 12, a signal indicating a rotation speed (turbine rotation speed) NT of the turbine shaft 30, a signal indicating an input shaft rotation speed NIN, a signal indicating an output shaft rotation speed NOUT, a signal indicating a throttle valve opening degree θTH of an electronic throttle valve 40, a signal indicating a coolant temperature THW of the engine 12, a signal indicating an intake air volume QAIR of the engine 12, a signal indicating an accelerator operation amount Acc, a signal indicating a brake on state BON, a signal indicating a fluid temperature THOIL of hydraulic fluid in the continuously variable transmission 18 or other devices, a signal indicating a lever position (operating position) PSH of a shift lever 74, signals indicating a battery temperature THBAT, a battery charge-discharge current IBAT, and a battery voltage VBAT, a signal indicating a secondary pressure Pout, and other signals, are supplied to the electronic control unit 50. The rotation angle (position) ACR of the crankshaft 13 and the engine rotation speed NE are detected by an engine rotation speed sensor 52. The turbine rotation speed NT is detected by a turbine rotation speed sensor 54. The input shaft rotation speed NIN is the input rotation speed of the continuously variable transmission 18 and is detected by an input shaft rotation speed sensor 56. The output shaft rotation speed NOUT is the output rotation speed of the continuously variable transmission 18 and is detected by an output shaft rotation speed sensor 58. The output shaft rotation speed NOUT corresponds to a vehicle speed V. The throttle valve opening degree θTH of the electronic throttle valve 40 is detected by a throttle sensor 60. The coolant temperature THW of the engine 12 is detected by a coolant temperature sensor 62. The intake air volume QAIR of the engine 12 is detected by an intake air volume sensor 64. The accelerator operation amount Acc that is the amount of operation of an accelerator pedal and that is an acceleration request amount of a driver is detected by an accelerator operation amount sensor 66. The brake on state BON indicates that an operating state of a foot brake that is a service brake is detected by a foot brake switch 68. The fluid temperature THOIL of hydraulic fluid in the continuously variable transmission 18 or other devices is detected by a CVT fluid temperature sensor 70. The lever position PSH of the shift lever 74 is detected by a lever position sensor 72. The battery temperature THBAT, the battery charge-discharge current IBAT, and the battery voltage VBAT are detected by a battery sensor 76. The secondary pressure Pout that is a fluid pressure supplied to the secondary pulley 46 is detected by a secondary pressure sensor 78. The electronic control unit 50, for example, calculates a state of charge (level of charge) (SOC) of a battery (electrical storage device) one after another based on the battery temperature THBAT, the battery charge-discharge current IBAT, the battery voltage VBAT, and the like. The electronic control unit 50, for example, calculates an actual speed ratio γ(=NIN/NOUT) of the continuously variable transmission 18 based on the output shaft rotation speed NOUT and the input shaft rotation speed NIN.
Engine output control instruction signals SE, hydraulic control instruction signals SCVT, and other instruction signals, are output from the electronic control unit 50. The engine output control instruction signals SE are used for output control over the engine 12. The hydraulic control instruction signals SCVT are used for hydraulic control related to a speed shift of the continuously variable transmission 18. Specifically, a throttle signal for controlling the open-close of the electronic throttle valve 40 by driving the throttle actuator 38, an injection signal for controlling the amount of fuel that is injected form a fuel injection device 80, an ignition timing signal for controlling the ignition timing of the engine 12 with an ignition device 82, and other signals are output as the engine output control instruction signals SE. An instruction signal for driving a first linear solenoid valve SLP that regulates the primary pressure Pin, an instruction signal for driving a second linear solenoid valve SLS that regulates the secondary pressure Pout, an instruction signal for driving a third linear solenoid valve SLT (not shown) that controls a line fluid pressure PL, and other signals are output to the hydraulic control circuit 100 as the hydraulic control instruction signals SCVT.
The shift lever 74 shown in
In
The clutch apply control valve 102 functions as a valve element that switches the status of supply of hydraulic fluid that is supplied to the forward clutch C1 and the reverse brake B1 via the manual valve 104 in accordance with the status of outputs of the first switching valve SC and second switching valve SL. The clutch apply control valve 102 includes a spool valve element 102a. The spool valve element 102a is movable in the direction of an axis. The spool valve element 102a is placed in any one of a normal position and a fail-garage position. In the normal position, hydraulic fluid that is supplied to the forward clutch C1 and the reverse brake B1 is the output fluid pressure LPM. In the fail-garage position, hydraulic fluid that is supplied to the forward clutch C1 and the reverse brake B1 is the control fluid pressure PSLU. The clutch apply control valve 102 includes a first input port 102b, a second input port 102c, a first output port 102d, a third input port 102e, a fourth input port 102f, a second output port 102g, a spring 102h, a first fluid chamber 102i, and a second fluid chamber 102j. The output fluid pressure LPM is input to the first input port 102b. The control fluid pressure PSLU is input to the second input port 102c. The first output port 102d is connected to an input port 104a of the manual valve 104, and communicates with any one of the first input port 102b and the second input port 102c depending on a switching position of the spool valve element 102a. The primary pressure Pin is input to the third input port 102e. The secondary pressure Pout is input to the fourth input port 102f via the check valve 120. The second output port 102g is connected to the primary pulley 42, and communicates with any one of the third input port 102e and the fourth input port 102f depending on a switching position of the spool valve element 102a. The spring 102h urges the spool valve element 102a toward the normal position. The first fluid chamber 102i receives the switching fluid pressure PSC to apply thrust to the spool valve element 102a in a direction toward the fail-garage position. The second fluid chamber 102j receives the second switching fluid pressure PSL to apply thrust to the spool valve element 102a in a direction toward the normal position.
In the thus configured clutch apply control valve 102, for example, when the switching fluid pressure PSC of the first switching valve SC is supplied to the first fluid chamber 102i, the spool valve element 102a is moved toward the fail-garage position against the urging force of the spring 102h. At this time, the second input port 102c and the first output port 102d communicate with each other, and the control fluid pressure PSLU of the fourth linear solenoid valve SLU is supplied to the input port 104a of the manual valve 104. That is, the control fluid pressure PSLU of the fourth linear solenoid valve SLU becomes an engaging fluid pressure for the forward clutch C1 (or the reverse brake B1) Since the control fluid pressure PSLU can be linearly varied based on the duty ratio of exciting current of the fourth linear solenoid valve SLU, an engagement transitional fluid pressure in process of engaging the forward clutch C1 (or the reverse brake B1) can be varied. For example, at the time of a garage shift (N-to-D shift or N-to-R shift) in which the shift lever 74 is operated from the “N” position to the “D” position or the “R” position when the vehicle is moving at a predetermined low vehicle speed, when the vehicle is stopped, or in other occasions, the control fluid pressure PSLU is regulated in accordance with a predetermined rule such that the forward clutch C1 (or the reverse brake B1) is smoothly engaged and engagement shock is reduced. The fourth input port 102f and the second output port 102g communicate with each other, and the secondary pressure Pout applied via the check valve 120 is supplied to the primary pulley 42.
On the other hand, when the first switching fluid pressure PSC is not output from the first switching valve SC or when the second switching fluid pressure PSL of the second switching valve SL is supplied to the second fluid chamber 102j, the spool valve element 102a is moved to the normal position side. At this time, the first input port 102b and the first output port 102d communicate with each other, and the output fluid pressure LPM is supplied to the input port 104a of the manual valve 104. That is, the output fluid pressure LPM becomes an engaging fluid pressure for the forward clutch C1 (or the reverse brake B1). Since the output fluid pressure LPM is a constant pressure regulated for an engine load, or the like (for example, input torque TIN), an engaged state is stably held after engagement of the forward clutch C1 (or the reverse brake B1) is complete. For example, the forward clutch C1 (or the reverse brake B1) is placed in a completely engaged state during steady time, or the like, after the garage shift in which the forward clutch C1 (or the reverse brake B1) is engaged, the output fluid pressure LPM is at least regulated to a predetermined constant pressure and is regulated with the addition of a fluid pressure according to the control fluid pressure PSLT. The third input port 102e and the second output port 102g communicate with each other, and the primary pressure Pin is supplied to the primary pulley 42.
In the manual valve 104, an engaging fluid pressure Pa (control fluid pressure PSLU or output fluid pressure LPM) output from the first output port 102d of the clutch apply control valve 102 is supplied to the input port 104a. When the shift lever 74 is operated to the “D” position or “L” position, the engaging fluid pressure Pa is supplied to the forward clutch C1 via a forward output port 104b, with the result that the forward clutch C1 is engaged. When the shift lever 74 is operated to the “R” position, the engaging fluid pressure Pa is supplied to the reverse brake B1 via a reverse output port 104c, with the result that the reverse brake B1 is engaged. When the shift lever 74 is operated to the “P” position or the “N” position, any of the fluid passages from the input port 104a to the forward output port 104b and the reverse output port 104c is interrupted and any of fluid passages for draining hydraulic fluid from the forward clutch C1 and the reverse brake B1 is communicated, with the result that both the forward clutch C1 and the reverse brake B1 are disengaged.
The primary pressure control valve 110 includes a spool valve element 110a, a spring 110b, a fluid chamber 110c, a feedback fluid chamber 110d, and a fluid chamber 110e. The spool valve element 110a is provided so as to be movable in the direction of an axis, and makes it possible to supply the line fluid pressure PL from an input port 110i to the third input port 102e of the clutch apply control valve 102 via an output port 110t by opening or closing the input port 110i. The spring 110b serves as an urging device that urges the spool valve element 110a in a valve opening direction. The fluid chamber 110c accommodates the spring 110b, and receives the first control fluid pressure PSLP to apply thrust to the spool valve element 110a in the valve opening direction. The feedback fluid chamber 110d receives the line fluid pressure PL output from the output port 110t to apply thrust to the spool valve element 110a in a valve closing direction. The fluid chamber 110e receives the modulator fluid pressure PM to apply thrust to the spool valve element 110a in the valve closing direction. The thus configured primary pressure control valve 110, for example, regulates the line fluid pressure PL by using the first control fluid pressure PSLp as a pilot pressure, and supplies the primary pressure Pin to the fluid chamber in the primary hydraulic cylinder 42c via the clutch apply control valve 102. For example, as the first control fluid pressure PSLp increases, the spool valve element 110a moves and, as a result, the primary pressure Pin increases. On the other hand, as the first control fluid pressure PSLp decreases, the spool valve element 110a moves and, as a result, the primary pressure Pin decreases.
The secondary pressure control valve 112 includes a spool valve element 112a, a spring 112b, a fluid chamber 112c, a feedback fluid chamber 112d, and a fluid chamber 112e. The spool valve element 112a is provided so as to be movable in the direction of an axis, and makes it possible to supply the line fluid pressure PL from an input port 112i to the secondary pulley 46 via an output port 112t as the secondary pressure Pout by opening or closing the input port 112i. The spring 112b serves as an urging device that urges the spool valve element 112a in a valve opening direction. The fluid chamber 112c accommodates the spring 112b, and receives the second control fluid pressure PSLS to apply thrust to the spool valve element 112a in the valve opening direction. The feedback fluid chamber 112d receives the secondary pressure Pout output from the output port 112g to apply thrust to the spool valve element 112a in a valve closing direction. The fluid chamber 112e receives the modulator fluid pressure PM to apply thrust to the spool valve element 112a in the valve closing direction. The thus configured secondary pressure control valve 112, for example, regulates the line fluid pressure PL by using the second control fluid pressure PSLS as a pilot pressure, and supplies the secondary pressure Pout to the fluid chamber in the secondary hydraulic cylinder 46c. For example, as the second control fluid pressure PSLS increases, the spool valve element 112a moves and, as a result, the secondary pressure Pout increases. On the other hand, as the second control fluid pressure PSLS decreases, the spool valve element 112a moves and, as a result, the secondary pressure Pout decreases.
In the thus configured hydraulic control circuit 100, for example, the primary pressure Pin that is regulated by the first linear solenoid valve SLP and the secondary pressure Pout that is regulated by the second linear solenoid valve SLS are controlled such that belt clamping forces that minimize a belt slip and that are not unnecessarily high are generated in the primary pulley 42 and the secondary pulley 46. In the correlation between the primary pressure Pin and the secondary pressure Pout, the speed ratio γ of the continuously variable transmission 18 is changed by changing the thrust ratio τ(=Wout/Win) between the primary pulley 42 and the secondary pulley 46 that are the pair of variable pulleys. For example, as the thrust ratio ti is increased, the speed ratio γ is increased (that is, the continuously variable transmission 18 shifts down).
The check valve 120 includes a poppet 120c and a spring 120d. The poppet 120c makes it possible to supply the secondary pressure Pout to be supplied from an input port 120a to the fourth input port 102f of the clutch apply control valve 102 via an output port 120b as the primary pressure Pin by opening or closing the input port 120a. The spring 120d serves as an urging device that urges the poppet 120c in a direction to close the input port 120a. In the thus configured check valve 120, when the secondary pressure Pout is applied from the input port 120a and, as a result, a pressing force generated by the secondary pressure Pout (=Pout×Pressure receiving area S120 of the poppet 120c) exceeds an urging force F120 of the spring 120d, the input port 120a and the output port 120b communicate with each other, and the secondary pressure Pout is supplied to the fourth input port 102f via the output port 120b. That is, when the secondary pressure Pout exceeds a cracking pressure Pk, a secondary pressure Pout′(=Pout−Pk) that is a surplus pressure over the cracking pressure Pk is supplied to the fourth input port 102f as the primary pressure Pin.
In this way, the check valve 120 regulates the primary pressure Pin to a predetermined pressure according to the secondary pressure Pout. Here, the check valve 120 regulates the primary pressure Pin in the description. This regulation made by the check valve 120 here means that the primary pressure Pin (secondary pressure Pout′) is set to a predetermined pressure according to the secondary pressure Pout based on check valve pressure regulation characteristics that depend on structural (mechanical) factors of the check valve 120 itself. That is, the regulation of pressure by the check valve 120 means that a pressure reduced to the primary pressure Pin (secondary pressure Pout′) set to a predetermined pressure according to the secondary pressure Pout is output.
The hydraulic control circuit 100 according to the embodiment includes the clutch apply control valve 102, and is able to switch the fluid pressure that is supplied to the primary pulley 42 to any one of the primary pressure Pin and the secondary pressure Pout′ via the check valve 120. Therefore, in the event of failure (in the event of occurrence of failure) where the primary pressure Pin is not normally output, fail-safe control is executed. Under the fail-safe control, the spool valve element 102a of the clutch apply control valve 102 is switched to the fail-garage position by outputting the first switching fluid pressure PSC, and the secondary pressure Pout″ supplied to the fourth input port 102f via the check valve 120 is supplied from the second output port 102g to the primary pulley 42. Examples of the event of failure assumes abnormal output of the first control fluid pressure PSLP, and valve sticking of the primary pressure control valve 110. Particularly, in the event of failure that causes an unintended downshift, execution of such fail-safe operation is effective.
In this way, the clutch apply control valve 102 functions as a valve element that switches the engaging fluid pressure that is supplied to the forward clutch C1 (or the reverse brake B1) to the output fluid pressure LPM during steady time and that switches the engaging fluid pressure to the control fluid pressure PSLU at the time of a garage shift. In addition, the clutch apply control valve 102 also functions as a valve element that switches the fluid pressure that is supplied to the primary pulley 42 to the primary pressure Pin during normal times and that causes fail-safe operation to switch the fluid pressure into the secondary pressure Pout′ via the check valve 120 in the event of failure.
Table 1 shows four hydraulic control modes that the hydraulic control system according to the embodiment is able to execute.
In hydraulic control mode (1), the first switching valve SC is in the OFF position, the second switching valve SL is in the OFF position, the primary pulley 42 is controlled with the first linear solenoid valve SLP, the secondary pulley 46 is controlled with the second linear solenoid valve SLS, the forward clutch C1 and the reverse brake B1 are placed in a Hi position at a constant pressure, and lockup of the torque converter 14 is in the OFF state. The hydraulic control mode (1) is used, for example, when the vehicle 10 starts moving, and allows the vehicle 10 to travel in a normal lockup OFF state.
In hydraulic control mode (2), the first switching valve SC is in the OFF position, the second switching valve SL is in the ON position, the primary pulley 42 is controlled with the first linear solenoid valve SLP, the secondary pulley 46 is controlled with the second linear solenoid valve SLS, the forward clutch C1 and the reverse brake B1 are placed in a Lo position at a constant pressure, and lockup of the torque converter 14 is in the ON state. A lockup differential pressure is controlled with the fourth linear solenoid valve SLU. The hydraulic control mode (2), for example, allows the vehicle 10 to travel in a normal lockup ON state. There is no torque amplification of the torque converter 14 and input torque reduces, so drag torque of a drum seal ring (not shown) of the forward clutch C1 is reduced by decreasing the pressure applied to the forward clutch C1. Thus, improvement of fuel consumption is achieved.
In hydraulic control mode (3), the first switching valve SC is in the ON position, the second switching valve SL is in the ON position, the primary pulley 42 is controlled with the first linear solenoid valve SLP, the secondary pulley 46 is controlled with the second linear solenoid valve SLS, the forward clutch C1 and the reverse brake B1 are placed in a Lo position at a constant pressure, and lockup of the torque converter 14 is placed in the OFF state. Although the second switching valve SL is in the ON position, lockup is placed in the OFF position when the first switching valve SC is set in the ON position. When both the first switching valve SC and the second switching valve SL are in the ON position, engine stall is prevented when lockup is placed in the OFF state. The hydraulic control mode (3) is used, for example, when the vehicle 10 decelerates before a stop. Although lockup is in the OFF state, the flow rate of fluid to pulley speed shift (belt return) is ensured by reducing the amount of fluid leakage in the solenoid through a decrease in the output fluid pressure LPM during deceleration, and improvement of fuel consumption is achieved.
In hydraulic control mode (4), the first switching valve SC is in the ON position, the second switching valve SL is in the OFF position, the primary pulley 42 is controlled with the second linear solenoid valve SLS, the secondary pulley 46 is controlled with the second linear solenoid valve SLS, the forward clutch C1 and the reverse brake B1 are controlled with the fourth linear solenoid valve SLU, and lockup of the torque converter 14 is placed in the OFF state. The hydraulic control mode (4) is used in, for example, garage shift control mode, fail-safe mode, neutral control, S&S control (described in the next paragraph), and other control.
The garage shift control mode is a mode in which the forward clutch C1 and the reverse brake B1 are controlled with the fourth linear solenoid valve SLU. The fail-safe mode is a mode in which the primary pressure Pin is not controlled with the first linear solenoid valve SLP (fail-safe mode intended for failure of the first linear solenoid valve SLP). The neutral control (N control) is control to continue releasing a clutch that transmits the output torque of the engine 12 to the continuously variable transmission 18 while the engine 12 runs at idle (autonomously rotates). The S&S control is control to disconnect the engine 12 from the power transmission path by placing the lockup clutch 26 in the OFF state during deceleration in the brake ON state where the foot brake is depressed while the vehicle is traveling forward, and to stop the rotation of the engine 12 by stopping, for example, supply of fuel to the engine 12.
The first switching valve SC switches whether to keep a constant pressure or gradually increase the pressure in the fluid passage of the forward clutch C1. Therefore, when the first switching valve SC is set in the ON position in hydraulic control mode (4), a shock due to application of a sudden constant pressure is reduced at the time of garage shift operation.
The valve body 150 that is a component of the hydraulic control circuit 100 according to the embodiment includes an upper valve body 151, a lower valve body 152, and a valve body plate 153. The valve body plate 153 is provided between the upper valve body 151 and the lower valve body 152. In the valve body 150, the lower valve body 152, the valve body plate 153, and the upper valve body 151 are stacked in this order. The valve body plate 153 includes an orifice 153a that is a hole extending through in the thickness direction of the upper valve body 151. The orifice 153a connects a fluid passage 151a of the upper valve body 151 and a fluid passage 152a of the lower valve body 152. The orifice 153a has the function of reducing fluid pressure.
The upper valve body 151 and the lower valve body 152 each have a plurality of fluid passages other than the fluid passage 151a or fluid passage 152a shown in
In the valve body 150 shown in
The inventors of the subject application diligently made a study over and over, and finally found that the difference between the pressures of both sides of the orifice significantly contributed to the flow rate and negative pressure of hydraulic fluid flowing through the orifice. For this reason, in the hydraulic control system according to the embodiment, for example, since an upstream pressure that is a fluid pressure on the upstream side of the orifice 153a in the direction of flow of hydraulic fluid is controlled with the second switching valve SL, the difference between the pressures of both sides of the orifice 153a is reduced by decreasing the pressure upstream of the orifice 153a with the second switching valve SL. Thus, generation of the radio-frequency noise is reduced. Similarly, since an upstream pressure that is a fluid pressure on the upstream side of an orifice 153b (see
In the hydraulic control system according to the embodiment, when the electronic control unit 50 determines that the vehicle 10 is stopped, the electronic control unit 50 executes hydraulic control such that the pressures upstream of the orifices 153a, 153b of the valve body plate 153 are decreased with the first switching valve SC and the second switching valve SL.
As described above, with the hydraulic control system according to the embodiment, when it is determined that the vehicle 10 is stopped, the pressures upstream of the orifices of the valve body plate 153 are decreased by the solenoid valves such as the first switching valve SC and the second switching valve SL, so no cavitation (ground noise) occurs. In a situation that high-frequency noise can be remarkable, generation of high-frequency noise is reduced by reducing the difference between the pressures of both sides of each orifice (the difference between the upstream-side pressure and downstream-side pressure of each orifice).
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-210070 | Nov 2018 | JP | national |
