JP2011196497A - Control device of idle stop vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent belt sliding and a starting delay, by properly controlling a linear solenoid valve for controlling supply oil pressure to a starting clutch when returning to an idle stop.SOLUTION: This control device includes the normally opening linear solenoid valve SLS for controlling the supply oil pressure to the starting clutch B1 and a solenoid valve driving circuit 100 for controlling the linear solenoid valve in response to a plurality of electric current-oil pressure characteristics. When returning from the idle stop, oil pressure generated by an oil pump is detected, and when its generating oil pressure is less than an allowable value, an indicator current to the linear solenoid valve is determined by selecting the electric current-oil pressure characteristics of increasing valve opening of the linear solenoid valve.

Description

The present invention relates to a control device for an idle stop vehicle, and more particularly to a control device for a continuously variable transmission and a start clutch when starting from an idle stop state.

Conventionally, an idle stop vehicle is known in which an engine is automatically stopped when a vehicle is stopped to suppress wasteful fuel consumption and generation of exhaust gas during idling. The engine stop condition in such an idle stop vehicle includes vehicle stop and brake ON, and the engine start condition includes brake OFF and accelerator pedal depression.

In such an idle stop vehicle, an oil pump driven by an engine, a belt-type continuously variable transmission whose output shaft is connected to drive wheels, a starting clutch provided between the engine and the continuously variable transmission, There is a vehicle including a continuously variable transmission and a hydraulic control device that supplies hydraulic pressure to a starting clutch based on the hydraulic pressure generated by the oil pump. In such a vehicle, the oil pump is also stopped along with the idle stop, so that the hydraulic oil is discharged from the continuously variable transmission and the starting clutch with time. After that, when the engine is driven from the idle stop state and the oil pump is driven by the engine, hydraulic oil is supplied to the continuously variable transmission and the starting clutch. At this time, the continuously variable transmission applies a predetermined belt clamping pressure. If the starting clutch is engaged before holding, there is a problem that belt slippage occurs.

There is known a system in which the hydraulic pressure supplied to the starting clutch is controlled by a normally open type linear solenoid valve. The reason for using the normally open type is to avoid the situation where the hydraulic pressure is always supplied to the starting clutch even when the power supply circuit of the linear solenoid valve is broken during the traveling so that the traveling becomes impossible. When such a normally open type linear solenoid valve is used, belt slippage is controlled by controlling the hydraulic pressure supplied to the starting clutch with the linear solenoid valve so that the clutch transmission torque does not exceed the belt transmission torque when returning to idle stop. It is conceivable to quickly engage the starting clutch while preventing this. For this purpose, it is necessary to first supply the maximum command current to the linear solenoid valve at the time of idling stop return to open the valve.

The linear solenoid valve follows a preset current-hydraulic characteristic (IP characteristic) under the condition that the supply hydraulic pressure, which is the original pressure, is equal to or higher than a predetermined value (for example, 1.2 MPa) and the supply voltage is a predetermined value (for example, 12 V). Output hydraulic pressure based on the command current is generated. However, since the oil pump that has been stopped is driven when the engine is started when the idle stop is returned, the oil pressure generated by the oil pump itself is low, and the supply hydraulic pressure of the linear solenoid valve does not increase immediately. Moreover, since a large current is required to drive the starter for starting the engine, the battery voltage temporarily decreases and the supply voltage to the linear solenoid valve is not sufficient. For this reason, even if an instruction current according to a preset current-hydraulic characteristic is supplied to the linear solenoid valve, the target output hydraulic pressure cannot be obtained, which causes a delay in engagement of the starting clutch.

Patent Document 1 discloses that in an idle stop vehicle using an oil pump driven by an engine as a hydraulic pressure supply source and equipped with a belt type continuously variable transmission, the start clutch is sufficiently engaged when the engine is restarted after the idle stop. Even if it is determined that the hydraulic pressure is high, there is known a type in which engagement is started after a predetermined time from the restart of the engine.

In Patent Document 1, a predetermined waiting time is set in order to solve the problem that the starting response varies depending on the secular change of the starting clutch and the oil temperature / idle stop time. The start of engagement is delayed, and a start delay after returning to idle stop occurs. Further, although a method of changing the waiting time according to the engagement pressure of the starting clutch and the oil temperature is disclosed, when the idle stop is restored, the oil pressure generated by the oil pump itself is low and the battery voltage also drops as described above. Therefore, even if the waiting time is determined according to the engagement pressure of the starting clutch and the oil temperature, the optimum time is not always reached.

JP 2007-24129 A

An object of the present invention is to provide a control device for an idle stop vehicle that can appropriately control a linear solenoid valve that controls a hydraulic pressure supplied to a start clutch when returning from an idle stop, thereby preventing a start delay.

To achieve the above object, the present invention provides an engine that is idle-stopped when a predetermined engine stop condition is satisfied, and that is started when a predetermined engine start condition is satisfied; and an oil pump driven by the engine; A continuously variable transmission that transmits engine power to drive wheels, a starting clutch provided between the engine and the continuously variable transmission, and a hydraulic pressure generated by the oil pump. In an idle stop vehicle comprising: a hydraulic control device that supplies hydraulic pressure to the transmission and the starting clutch, and controls a belt clamping pressure of the continuously variable transmission and an engaging force of the starting clutch, the hydraulic control device includes: Belt clamping pressure detecting means for detecting a belt clamping pressure of the continuously variable transmission, and a belt transmission torque of the continuously variable transmission from the detected belt clamping pressure. And a target clutch pressure of the starting clutch so that the clutch transmitting torque of the starting clutch does not exceed the calculated belt transmitting torque when the belt clamping pressure is a predetermined value or less. Means, a linear solenoid valve for controlling the hydraulic pressure supplied to the starting clutch, and a plurality of current-hydraulic characteristics, and the linear clutch valve is set to achieve the target clutch pressure based on any one of the current-hydraulic characteristics. A solenoid valve driving means for outputting an instruction current to the solenoid valve; and a hydraulic pressure detecting means for detecting a value related to the hydraulic pressure generated by the oil pump, wherein the solenoid valve driving means is detected by the hydraulic pressure detecting means. Compared to the case where the oil pressure generated by the oil pump is less than the allowable value, Te, the valve opening of the linear solenoid valve becomes larger current - on the basis of the hydraulic pressure characteristic, and outputs the command current to the linear solenoid valve, to provide a control device for the idle stop vehicle.

At the time of idling stop return, in order to prevent belt slip, the target clutch pressure of the start clutch is set so that the clutch transmission torque capacity does not exceed the belt transmission torque capacity, and the clutch pressure is controlled to be the target clutch pressure. . The clutch pressure of the starting clutch can be controlled by the indicated current (duty ratio) of the linear solenoid valve. The linear solenoid valve is operated with a predetermined current-hydraulic characteristic, but the current-hydraulic characteristic is effective only under the condition that the supply hydraulic pressure as the original pressure is a predetermined value (for example, 1.2 MPa) or more. However, the linear solenoid valve cannot generate a predetermined output hydraulic pressure even if the same command current is input under the condition that the discharge pressure of the oil pump is low, such as immediately after returning from idle stop.

Therefore, in the present invention, when a plurality of current-hydraulic characteristics (IP characteristics) for operating the linear solenoid valve are set, and the discharge pressure of the oil pump during engine cranking is less than the allowable value The current-hydraulic characteristic that increases the valve opening of the linear solenoid valve is selected, and the command current is output to the linear solenoid valve according to the characteristic. As a result, the command current for obtaining a predetermined target clutch pressure can be changed to increase the valve opening of the linear solenoid valve (in the case of a normally open type linear solenoid valve, the command current is lowered), and immediately after the return to idle stop. Even under such low oil pressure conditions, the target clutch pressure can be approached in a shorter time.

In the present invention, the belt clamping pressure detecting means for detecting the belt clamping pressure of the continuously variable transmission and the oil pressure detecting means for detecting the oil pressure generated by the oil pump are used, but one detecting means is replaced by the other detecting means. It can be substituted. In general, the discharge pressure of the oil pump is supplied to the oil chamber of the secondary pulley via the regulator valve and the pinching control valve, but the oil pump discharge pressure does not reach the predetermined line pressure when returning to idle stop. The discharge pressure of the pump is directly supplied to the oil chamber of the secondary pulley via the pinching control valve. In other words, the secondary pressure (belt clamping pressure) and the discharge pressure of the oil pump are substantially the same pressure, and if the belt clamping pressure is detected, the discharge pressure of the oil pump can also be known.

In general, the linear solenoid valve has a so-called hysteresis in which the current-hydraulic characteristics differ between when the command current decreases and when it increases. At the time of idling stop return, the battery voltage is temporarily lowered due to the starter drive, so that the supply voltage to the linear solenoid valve is also lowered, so that the hysteresis of the linear solenoid valve is increased and the desired output hydraulic pressure is not lost. Therefore, a means for detecting the battery voltage or the power supply voltage of the linear solenoid valve is further provided, and when the detected battery voltage or the power supply voltage of the linear solenoid valve is less than the reference value, the solenoid valve driving means It is desirable to output the command current to the linear solenoid valve based on the current-hydraulic characteristic in which the hysteresis of the linear solenoid valve becomes larger than in the above case. That is, under a low voltage just after the return to idle stop, the target solenoid pressure can be made closer by controlling the linear solenoid valve using a current-hydraulic characteristic different from that in the normal state in consideration of hysteresis.

As described above, according to the present invention, the slippage of the starting clutch is made close to the target clutch pressure so that the clutch transmission torque capacity does not exceed the belt transmission torque capacity. Under conditions of low hydraulic pressure, such as immediately after return, the command current is output according to the current-hydraulic characteristics in which the valve opening of the linear solenoid valve increases, so that the target clutch pressure can be approached in a short time. The delay in starting can be prevented by eliminating the engagement delay.

It is a skeleton figure which shows the structure of the idle stop vehicle which concerns on this invention. FIG. 2 is a hydraulic circuit diagram of the continuously variable transmission shown in FIG. 1. It is a figure which shows each characteristic of a line, a clutch modulator pressure, a clutch control pressure, and a secondary pressure with respect to solenoid pressure Psls. It is an IP characteristic view of a linear solenoid valve when the supply pressure is 1.2 MPa, 0.5 MPa, 0.3 MPa, and 0.1 MPa. It is an IP characteristic figure of a linear solenoid valve when supply voltage is 12V and 8.5V. (A) is a time change chart of engine speed and battery voltage at the time of idling stop return, (b) is pump discharge pressure, secondary pressure, target clutch pressure, actual clutch pressure at the time of idling stop return (before the present invention and countermeasures) FIG. It is a flowchart figure of an example of the control method concerning this invention.

FIG. 1 shows an example of the configuration of an idle stop vehicle according to the present invention. The output shaft 1 a of the engine 1 is connected to the drive shaft 32 via the continuously variable transmission 2. The continuously variable transmission 2 is provided with a torque converter 3, a transmission 4, a hydraulic control device 7, an oil pump 6 driven by the engine 1, and the like. The engine 1 is provided with a starter (cell motor) 1b for starting the engine.

The continuously variable transmission 2 includes a forward / reverse switching device 8, a primary pulley 11, a secondary pulley 21, and a V that is wound between the pulleys and transmits the rotation to the primary shaft 10 by switching the rotation of the turbine shaft 5 of the torque converter 3 between forward and reverse. The transmission 4 includes a belt 15, a differential device 30 that transmits the power of the secondary shaft 20 to the drive shaft 32, and the like. The turbine shaft 5 and the primary shaft 10 are arranged on the same axis, and the secondary shaft 20 and the drive shaft 32 are arranged parallel to the turbine shaft 5 and non-coaxially. Therefore, the continuously variable transmission 2 has a three-axis configuration as a whole. The V belt 15 used here is, for example, a known compression drive type metal belt composed of an endless tension band and a number of blocks slidably supported by the tension band.

The forward / reverse switching device 8 includes a planetary gear mechanism 80, a reverse brake B1, and a direct connection clutch C1, and the reverse brake B1 or the direct connection clutch C1 corresponds to the start clutch in the present invention. The reverse brake B1 and the direct coupling clutch C1 are wet multi-plate brakes and clutches, respectively. A sun gear 81 of the planetary gear mechanism 80 is connected to the turbine shaft 5 as an input member, and a ring gear 82 is connected to the primary shaft 10 as an output member. The planetary gear mechanism 80 is a single pinion system, the reverse brake B1 is provided between the carrier 84 supporting the pinion gear 83 and the transmission case, and the direct coupling clutch C1 is provided between the carrier 84 and the sun gear 81. When the direct clutch C1 is released and the reverse brake B1 is engaged, the rotation of the turbine shaft 5 is reversed and decelerated and transmitted to the primary shaft 10. Then, the drive shaft 32 rotates in the same direction as the engine rotation direction via the secondary shaft 20, so that the vehicle travels forward. On the contrary, when the reverse brake B1 is released and the direct clutch C1 is engaged, the carrier 84 and the sun gear 81 rotate together, so that the turbine shaft 5 and the primary shaft 10 are directly connected. Then, since the drive shaft 32 rotates in the direction opposite to the engine rotation direction via the secondary shaft 20, a reverse traveling state is set.

The primary pulley 11 of the transmission 4 includes a fixed sheave 11a that is integrally fixed on the primary shaft 10, and a movable sheave 11b that is supported on the primary shaft 10 so as to be axially movable and integrally rotatable. Yes. A cylinder 12 fixed to the primary shaft 10 is provided behind the movable sheave 11 b, and an oil chamber 13 is formed between the movable sheave 11 b and the cylinder 12. Shift control is performed by controlling the amount of oil supplied to the oil chamber 13.

The secondary pulley 21 includes a fixed sheave 21a that is integrally fixed on the secondary shaft 20, and a movable sheave 21b that is supported on the secondary shaft 20 so as to be axially movable and integrally rotatable. A piston 22 fixed to the secondary shaft 20 is provided behind the movable sheave 21 b, and an oil chamber 23 is formed between the movable sheave 21 b and the piston 22. By controlling the hydraulic pressure supplied to the oil chamber 23, a belt clamping pressure necessary for torque transmission is applied. The oil chamber 23 may be provided with a bias spring that applies an initial clamping pressure. In the supply oil passage in the vicinity of the oil chamber 23 of the secondary pulley 21, a hydraulic pressure sensor 108 that detects the supply oil pressure of the oil chamber 23 is provided as will be described later.

One end portion of the secondary shaft 20 extends toward the engine side, and the output gear 27 is fixed to this end portion. The output gear 27 meshes with the ring gear 31 of the differential device 30, and power is transmitted from the differential device 30 to the drive shaft 32 extending left and right to drive the wheels.

The engine 1 and the continuously variable transmission 2 are controlled by the electronic control unit 100. The electronic control unit 100 includes an engine speed sensor 101, a vehicle speed (or secondary pulley speed) sensor 102, a throttle opening (or accelerator opening) sensor 103, a shift position sensor 104, a primary pulley speed (or turbine speed). ) Signals are input from the sensor 105, the brake signal sensor 106, the hydraulic oil temperature sensor 107 of the CVT, the hydraulic pressure sensor 108 that detects the hydraulic pressure supplied to the secondary pulley 21, and the battery voltage sensor 109. In addition, a road surface inclination angle, an idle signal, a start signal, an engine water temperature, an intake air amount, an air conditioner signal, an ignition signal, and the like may be input as input signals. For the sake of simplicity, FIG. 1 shows an example in which both the engine 1 and the continuously variable transmission 2 are controlled by a single electronic control unit 100, but in actuality, control is performed by individual electronic control units. Both electronic control units are linked to each other by a communication bus.

The electronic control unit 100 performs idle stop control that stops the engine 1 (idle stop) when the engine stop condition is satisfied and drives the starter 1b to restart the engine 1 when the engine restart condition is satisfied. To do. The engine stop condition includes, for example, vehicle stop and brake ON (depressing the brake pedal). However, idling stop is not permitted when the engine water temperature is low, when the battery voltage is exhausted, when the electric load is large, or when the accelerator pedal is depressed. On the other hand, the engine restart condition (idle stop return condition) includes, for example, brake OFF, accelerator pedal depression, vehicle speed signal input, and the like. Since the engine stop condition and the restart condition are publicly known, detailed description is omitted here.

The electronic control device 100 controls a solenoid valve built in the hydraulic control device 7. The hydraulic control device 7 is connected to the oil pump 6, the primary oil chamber 13, the secondary oil chamber 23, the reverse brake B1, and the direct coupling clutch C1 through a pipe. The electronic control device 100 determines the target primary rotational speed according to a preset shift map according to the vehicle speed and the throttle opening, and controls the duty solenoid valves DS1 and DS2 in the hydraulic control device 7 to control the primary oil pressure. The amount of oil supplied to the chamber 13 is adjusted, the primary rotational speed is controlled to be shifted to the target value, and the linear solenoid valve SLS is controlled to generate a belt slip in the hydraulic pressure (belt clamping pressure) of the secondary oil chamber 23. Controls to a value that is not allowed. Further, the hydraulic control device 7 also has a function of controlling the hydraulic pressure supplied to the reverse brake B1 and the direct coupling clutch C1 using the linear solenoid valve SLS. The engagement control of the starting clutch B1 is also included.

FIG. 2 is a hydraulic circuit diagram of an example of the hydraulic control device 7. In FIG. 2, 71 is a regulator valve, 72 is a clutch modulator valve, 73 is a solenoid modulator valve, 74 is a garage shift valve, 75 is a manual valve, 76 is an upshift ratio control valve, 77 is a downshift ratio control valve, 78 is a ratio check valve and 79 is a clamping pressure control valve. Further, the linear solenoid valve SLS outputs solenoid pressure Psls in order to perform line pressure regulation control, transient control of the reverse brake B1 and direct coupling clutch C1, and pressure regulation control of the oil chamber 23 of the secondary pulley 21. DS1 is an upshift solenoid valve that controls the pressure of the upshift signal pressure Pds1, and DS2 is a downshift solenoid valve that controls the pressure of the downshift signal pressure Pds2. The solenoid valves DS1 and DS2 also have a function as a solenoid valve that generates a signal pressure for switching the garage shift valve 74 to the transient pressure side. In this embodiment, the linear solenoid valve SLS uses a normally open linear solenoid valve, and the solenoid valves DS1 and DS2 both use a normally closed duty solenoid valve.

In FIG. 2, only the hydraulic circuit relating to the primary pulley 11, the secondary pulley 21, the reverse brake B1 and the direct coupling clutch C1 is shown. However, the hydraulic circuit of the lock-up clutch 3a built in the torque converter 3 is the same as that of the present invention. Omitted because there is no direct relationship. Note that the hydraulic pressure supply source of the hydraulic control device 7 is only the oil pump 6 driven by the engine 1, and no special oil pump such as an electric pump is provided.

The regulator valve 71 is a valve that regulates the discharge pressure of the oil pump 6 to a predetermined line pressure P _L, and regulates the line pressure P _L according to the solenoid pressure Psls input to the signal port 71a.

The clutch modulator valve 72 is a valve that outputs a clutch modulator pressure Pcm that is a source pressure of supply pressures (P _C1 , P _B1 ) to the direct coupling clutch C1 and the reverse brake B1. The line pressure P _L is input to the input port 72a, and the clutch modulator pressure Pcm is output from the output port 72b. The output pressure is fed back to the first signal port 72c so as to face the spring load. Therefore, the clutch modulator pressure Pcm is adjusted to a constant pressure corresponding to the spring load.

The solenoid modulator valve 73 is a valve that regulates the clutch modulator pressure Pcm and generates a constant solenoid modulator pressure Psm corresponding to the spring load. The solenoid modulator pressure Psm is the original pressure of the upshift solenoid valve DS1 and the downshift solenoid valve DS2, and is also supplied to the garage shift valve 74 and the clamping pressure control valve 79.

The manual valve 75 is a manually operated valve mechanically connected to the shift lever. The manual valve 75 is switched to each range of P, R, N, D, S, and B, and the hydraulic pressure supplied from the garage shift valve 74 is directly coupled to the clutch C1. Alternatively, it selectively leads to the reverse brake B1. The input port 75a is supplied with hydraulic pressure from the garage shift valve 74, the output port 75b is connected to the direct clutch C1, and the output ports 75c and 75d are both connected to the reverse brake B1. In the R range, the manual valve 75 supplies hydraulic pressure to the direct clutch C1 and drains the hydraulic pressure of the reverse brake B1. In the D, S, and B ranges, the manual valve 75 supplies hydraulic pressure to the reverse brake B1 and drains the hydraulic pressure of the direct clutch C1. In the P and N ranges which are non-traveling ranges, the hydraulic pressures of the direct clutch C1 and the reverse brake B1 are drained together.

The upshift ratio control valve 76 and the downshift ratio control valve 77 adjust the amount of hydraulic oil supplied to and discharged from the primary oil chamber 13 according to the relative relationship between the upshift signal pressure Pds1 and the downshift signal pressure Pds2. This is a flow control valve. Further, the ratio check valve 78 switches the primary oil chamber 13 from the flow rate control to the hydraulic control for closing control, and the ratio between the hydraulic pressure of the primary oil chamber 13 and the hydraulic pressure of the secondary oil chamber 23 is set in advance. It is a valve for maintaining the relationship and maintaining the gear ratio. The upshift ratio control valve 76 and the downshift ratio control valve 77 are known from, for example, Japanese Patent Application Laid-Open No. 2007-263207, and the description thereof is omitted.

The clamping pressure control valve 79 is a pressure control valve for controlling the hydraulic pressure of the secondary oil chamber 23, and includes a spool biased in one direction by a spring. A constant pressure Psm is supplied from the solenoid modulator valve 73 to the signal port 79a at one end facing the spring load. Line pressure P _L is supplied to the input port 79b, the output port 79c is connected to the secondary oil chamber 23, and the output pressure is fed back to the port 79d. Solenoid pressure Psls is supplied to the signal port 79e on the other end side in which the spring is accommodated. Therefore, the hydraulic pressure obtained by amplifying the solenoid pressure Psls input to the signal port 79e with a predetermined amplification degree can be supplied to the secondary oil chamber 23. The oil pressure (secondary pressure) in the secondary oil chamber 23 is detected by the oil pressure sensor 108, and the belt transmission torque can be obtained based on the detected oil pressure.

The garage shift valve 74 is for switching the oil passage so that the supply pressure to the direct coupling clutch C1 and the reverse brake B1 can be transiently controlled when the shift lever is switched from N → D or N → R (at the time of garage shift). It is a switching valve. The right side of the center line in FIG. 2 is the transient state, and the left side is the holding state. A spool 74b urged in one direction by a spring 74a is provided, and signal ports 74c and 74d to which an upshift signal pressure Pds1 and a downshift signal pressure Pds2 are input in the same direction as the spring load are formed. Yes. A solenoid modulator pressure Psm is input to the counter port 74h in a direction opposite to the spring load. Since the solenoid valves DS1 and DS2 are both turned on during the garage shift, the signal pressures Pds1 and Pds2 inputted to the signal ports 74c and 74d are both turned on, and the spool 74b moves downward against the spring 74a and moves to the right side. It becomes a transient state. The solenoid pressure (transient pressure) Psls input to the port 74e is output from the output port 74f and supplied to the direct coupling clutch C1 or the reverse brake B1 via the manual valve 75. Therefore, engagement can be started gently while avoiding the engagement shock of the direct clutch C1 or the reverse brake B1 by the solenoid pressure Psls. When at least one of the signal pressures Pds1 and Pds2 is turned OFF, the left side is held, and the clutch modulator pressure (holding pressure) Pcm input to the port 74g is output from the output port 74f and is directly coupled via the manual valve 75. C1 or reverse brake B1 is supplied. Therefore, the engagement state of the direct clutch C1 or the reverse brake B1 can be maintained regardless of the operation of the linear solenoid valve SLS. At the time of idling stop return, the garage shift valve 74 is held at the transition position, and the solenoid pressure Psls controlled by the linear solenoid valve SLS is supplied to the reverse brake B1 or the direct coupling clutch C1. As described later, the solenoid pressure Psls controls the transmission torque capacity of the starting clutch B1 so that the torque transmitted to the primary shaft 10 via the starting clutch B1 does not exceed the belt transmission torque capacity. Can be prevented.

The manual valve 75 is a manually operated valve mechanically connected to the shift lever. The manual valve 75 is switched to each range of P, R, N, D, S, and B, and the hydraulic pressure supplied from the garage shift valve 74 is directly coupled to the clutch C1. Alternatively, it selectively leads to the reverse brake B1. The input port 75a is supplied with hydraulic pressure from the garage shift valve 74, the output port 75b is connected to the direct clutch C1, and the output ports 75c and 75d are both connected to the reverse brake B1. In the R range, the manual valve 75 supplies the hydraulic pressure to the direct clutch C1 and drains the hydraulic pressure of the reverse brake B1. In the D, S, and B ranges, the manual valve 75 supplies the hydraulic pressure to the reverse brake B1 and drains the hydraulic pressure of the direct clutch C1. . In the P and N ranges, which are non-traveling ranges, the hydraulic pressures of the direct clutch C1 and the reverse brake B1 are drained together.

FIG. 3 shows characteristics of the line pressure P _L , the clutch modulator pressure Pcm, the clutch control pressure, and the secondary pressure with respect to the solenoid pressure Psls. The line pressure P _L is adjusted to a hydraulic pressure substantially proportional to the solenoid pressure Psls. The clutch modulator pressure Pcm is the same as the line pressure P _L until the solenoid pressure Psls reaches a predetermined value, and is limited to a constant pressure when it exceeds the predetermined value. Further, since the solenoid pressure Psls is directly supplied to the reverse brake B1 or the direct coupling clutch C1 in a transient state, the clutch control pressure becomes the solenoid pressure Psls itself. The secondary pressure is proportional to the solenoid pressure Psls and is adjusted to a hydraulic pressure slightly lower than the hydraulic line pressure P _L. As shown in FIG. 2, the clutch control pressure and the secondary pressure are both controlled by the solenoid pressure Psls, but the secondary pressure is always set to exceed the clutch control pressure. The secondary pressure is detected by the hydraulic pressure sensor 108.

The linear solenoid valve SLS is duty controlled. The duty control is also called pulse width modulation control (PWM), and the duty ratio (indicated current) is changed by changing the ratio (duty ratio) of the ON time to the period of the pulse signal supplied to the linear solenoid valve SLS. It generates a substantially proportional output oil pressure. The reason why the duty signal is used is that the instruction current to the linear solenoid valve SLS can be controlled by a computer, and the output hydraulic pressure is regulated while the linear solenoid valve is always operated to reduce the change in hydraulic pressure due to friction.

FIG. 4 shows an example of the current-hydraulic characteristic (IP characteristic) of the linear solenoid valve at a supply voltage of 12V. Since the linear solenoid valve SLS is a normally open type, the output hydraulic pressure decreases as the current value increases. Among these, the characteristic A is a characteristic when the original pressure (strictly, the clutch modulator pressure) of the linear solenoid valve is 1.2 MPa (normal time), and the output hydraulic pressure can be controlled in a wide range from 0 to 1.2 MPa. . On the other hand, characteristics B to D are characteristics when the original pressure of the linear solenoid valve is 0.5 MPa, 0.3 MPa, and 0.1 MPa, and the maximum hydraulic pressure is limited to 0.5 MPa, 0.3 MPa, and 0.1 MPa, respectively. Therefore, even if the current value is decreased, the output hydraulic pressure higher than the original pressure is not generated. Here, an example in which the hydraulic pressures of the four characteristics A to D decrease as the current increases is not necessarily limited to this, and can be arbitrarily set as long as the current and the hydraulic pressure have a predetermined relationship.

In the present invention, when the original pressure of the linear solenoid valve is low, such as during engine cranking, characteristics BD that increase the valve opening degree of the linear solenoid valve according to the original pressure are selected, and the original after the engine is started When the pressure is stable, the characteristic A is selected and an instruction current is output to the linear solenoid valve. For example, in order to obtain the hydraulic pressure of 0.1 MPa in FIG. 4, a high instruction current (I ₁ ) is required in the characteristic A, but in the characteristic D, any current value can be used as long as the current value is less than the current value I _2. An oil pressure of 0.1 MPa equal to the pressure can be supplied. When the current value decreases, the opening degree of the linear solenoid valve increases, so that the hydraulic response is improved. In other words, under conditions where the original pressure is low, such as during cranking, the hydraulic response to the target clutch pressure of the starting clutch is increased by selecting a characteristic that increases the valve opening of the linear solenoid valve.

FIG. 5 shows an example of current-hydraulic characteristics of the linear solenoid valve when the supply pressure is 1.2 MPa and the supply voltage is 12V and 8.5V. As shown in FIG. 5, the linear solenoid valve has hysteresis at the time of current drop and at the time of current upper layer, and the hysteresis increases as the supply voltage decreases. For example, when the [Delta] H ₁₂ hysteresis when the 12V, hysteresis when 8.5V is increased to [Delta] H _8.5. An increase in hysteresis means a decrease in the slidability of the linear solenoid valve, leading to a decrease in hydraulic response. The drop in the supply voltage occurs due to the drop in the battery voltage accompanying the starter drive, and the battery voltage during cranking drops to about 8.5 V as shown in FIG. Therefore, when the supply voltage becomes lower than the reference value, the hydraulic solenoid response can be suppressed from decreasing with an increase in hysteresis by controlling the linear solenoid valve using an IP characteristic different from that in the normal state. Although the case where the supply voltage is 12V and the case where the supply voltage is 8.5V is shown here, it is needless to say that other characteristics may be set.

Next, changes in engine speed, battery voltage, pump discharge pressure, secondary hydraulic pressure, and clutch pressure of the start clutch B1 at the time of idle stop recovery according to the present invention will be described with reference to FIG.

Since the oil pump stops during the idle stop, all the hydraulic pressure is drained and the command signal to the linear solenoid valve SLS is also turned OFF. The garage shift valve 74 is held in a transient position by a spring.

When the engine start condition is satisfied at time 0 (determination of idle stop return), the engine is started by the starter 1b. At this time, since a large current is required to drive the starter, the battery voltage temporarily decreases. Although the discharge pressure of the oil pump increases as the engine speed increases, the rate of increase is slow during cranking, and the increase in secondary pressure is also delayed. During cranking, the belt clamping pressure is obtained from the secondary pressure detected by the hydraulic sensor 108, and the belt transmission torque is calculated from this belt clamping pressure. As this calculation method, for example, the secondary clamping pressure can be calculated from the secondary pressure and the pressure receiving area, and the belt transmission torque can be calculated from the secondary clamping pressure, the friction coefficient with the belt, the winding diameter, and the like. Then, the target clutch pressure of the starting clutch is set so that the clutch transmission torque of the starting clutch does not exceed the belt transmission torque. However, since the pump discharge pressure, which is the original pressure, is low, even if the command current is commanded to the linear solenoid valve so as to reach the target clutch pressure, the output hydraulic pressure does not follow, and the actual clutch pressure cannot follow. The actual clutch pressure indicated by the broken line in FIG. 6B is the case where the linear solenoid valve is controlled using normal IP characteristics (see A in FIG. 4), and the actual clutch pressure almost increases until cranking is completed. I understand that I do not. Furthermore, the ability to follow the target clutch pressure is poor even after cranking is completed.

Therefore, in the present invention, in addition to the normal IP characteristics, IP characteristics for low hydraulic pressure during cranking (see B to D in FIG. 4) are set separately, and the secondary pressure is set to an allowable value (for example, 0). .2 MPa), an IP characteristic (for example, D characteristic) that increases the valve opening of the linear solenoid valve according to the secondary pressure is selected, and an instruction current is output to the linear solenoid valve according to this characteristic. In the D characteristic, since the opening degree of the linear solenoid valve is larger than that in the A characteristic, it can be seen that the actual clutch pressure starts to increase in the middle of the cranking and the followability to the target clutch pressure is improved. However, since the target clutch pressure is set so that the clutch transmission torque of the starting clutch does not exceed the belt transmission torque, belt slippage can be reliably prevented.

After the start clutch B1 is engaged, at least one of the solenoid valves DS1 and DS2 is turned OFF, so the garage shift valve 74 is switched to the hold position, and the hold pressure (clutch modulator pressure Pcm) is supplied to the start clutch B1. It is held in a fastened state. Thereafter, the clamping pressure control valve 79 is controlled by the solenoid pressure Psls of the linear solenoid valve SLS, and the secondary pressure is controlled so that the belt clamping pressure corresponding to the transmission torque is obtained.

FIG. 7 shows a flowchart of an example of a starting clutch control method according to the present invention. When the control is started, first, the secondary pressure is detected by the hydraulic sensor 108 (S1), and then the belt transmission torque is calculated from the secondary pressure (S2). Next, the target clutch pressure of the starting clutch is set so that the clutch transmission torque of the starting clutch does not exceed the calculated belt transmission torque. That is, the upper limit of the target clutch pressure is set (S3). Next, the secondary pressure is compared with an allowable value (S4). The allowable value may be set to the maximum hydraulic pressure during cranking, for example, 0.2 MPa. If the secondary pressure is greater than or equal to the allowable value, the IP characteristic of the linear solenoid valve is selected as A (see FIG. 4) (S5), and if the secondary pressure is less than the allowable value, BD depending on the secondary pressure. One of the IP characteristics (see FIG. 4) is selected (S6). Thereafter, the battery voltage is detected (S7), the hysteresis according to the battery voltage is determined (S8), and the command current to the linear solenoid valve is determined according to the selected IP characteristic and hysteresis (S9).

In the above embodiment, the linear solenoid valve that controls the clutch pressure of the starting clutch and the linear solenoid valve that controls the secondary pressure of the continuously variable transmission are shared by one solenoid valve. However, the present invention is not limited to this. The hydraulic control of both may be performed individually using individual linear solenoid valves.

The hydraulic circuit of the continuously variable transmission and the starting clutch is not limited to that shown in FIG. For example, instead of directly supplying the output hydraulic pressure Psls by the linear solenoid valve to the starting clutch, the output hydraulic pressure Psls is supplied to the pressure control valve as a signal hydraulic pressure, and the output hydraulic pressure of the pressure control valve is supplied to the starting clutch. Is possible.

1 Engine 1b Starter 2 Continuously Variable Transmission 4 Transmission 6 Oil Pump 7 Hydraulic Control Device 11 Primary Pulley 21 Secondary Pulley 71 Regulator Valve 72 Clutch Modulator Valve 73 Solenoid Modulator Valve 74 Garage Shift Valve 75 Manual Valve 76 Upshift Ratio Control Valve 77 Ratio control valve for downshift 78 Ratio check valve 79 Nipping pressure control valve 80 Planetary gear mechanism 100 Electronic control unit (ECU)
101 Engine speed sensor 102 Vehicle speed sensor 103 Throttle opening sensor 104 Shift position sensor 105 Primary pulley speed sensor 106 Brake sensor 107 Oil temperature sensor 108 Oil pressure sensor 109 Battery voltage B1 Reverse brake (start clutch)
C1 Direct coupling clutch SLS Linear solenoid valve DS1 Duty solenoid valve DS2 Duty solenoid valve Psls Solenoid pressure

Claims (2)

An engine that is idle-stopped when a predetermined engine stop condition is satisfied, and that is started when a predetermined engine start condition is satisfied;
An oil pump driven by the engine;
A belt-type continuously variable transmission that transmits engine power to drive wheels;
A starting clutch provided between the engine and the continuously variable transmission;
A hydraulic control device for supplying a hydraulic pressure to the continuously variable transmission and the starting clutch based on a hydraulic pressure generated by the oil pump, and controlling a belt clamping pressure of the continuously variable transmission and an engaging force of the starting clutch; In the idle stop car with
The hydraulic control device includes:
Belt clamping pressure detecting means for detecting the belt clamping pressure of the continuously variable transmission;
A transmission torque calculating means for calculating a belt transmission torque of the continuously variable transmission from the detected belt clamping pressure;
Means for setting a target clutch pressure of the starting clutch so that the clutch transmission torque of the starting clutch does not exceed the calculated belt transmission torque when the belt clamping pressure is equal to or less than a predetermined value;
A linear solenoid valve for controlling the hydraulic pressure supplied to the starting clutch;
Solenoid valve driving means for setting a plurality of current-hydraulic characteristics and outputting an instruction current to the linear solenoid valve so as to be the target clutch pressure based on any of the current-hydraulic characteristics;
A hydraulic pressure detecting means for detecting a value related to the generated hydraulic pressure of the oil pump,
The solenoid valve driving means is configured such that when the oil pressure generated by the oil pump detected by the oil pressure detection means is less than an allowable value, the linear solenoid valve is compared with a case where the oil pressure generated by the oil pump is greater than or equal to an allowable value. A control device for an idling stop vehicle, characterized in that an instruction current is output to the linear solenoid valve based on a current-hydraulic characteristic in which the valve opening of the valve increases. The hydraulic control device further includes means for detecting a battery voltage or a power supply voltage of the linear solenoid valve,
When the detected battery voltage or the power supply voltage of the linear solenoid valve is less than a reference value, the solenoid valve driving means has greater hysteresis of the linear solenoid valve than when the voltage is higher than the reference value. 2. The control apparatus for an idle stop vehicle according to claim 1, wherein an instruction current is output to the linear solenoid valve based on a current-hydraulic characteristic.

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