JP2011043225A - Starting clutch control device for idling-stop vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a starting clutch control device for an idling-stop vehicle, capable of preventing belt slippage when starting from an idling-stop state. <P>SOLUTION: Belt slippage prevention control to supply a clutch pressure so as not to cause the belt slippage of a continuously variable transmission and clutch pressure increase control to increase the clutch pressure with a predetermined time inclination are successively performed as engagement control of the starting clutch at restart from an engine automatic stop state. The belt slippage prevention control calculates a belt transmission torque from a belt clamping pressure of the continuously variable transmission, and controls the clutch pressure according to the target clutch pressure corresponding to belt transmission torque until a target clutch pressure of the starting clutch reaches a predetermined value so that the clutch transmission torque of the starting clutch does not exceed a belt transmission torque calculation value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  2. Description of the Related Art Conventionally, an idle stop vehicle is known in which an engine is automatically stopped when the vehicle is stopped to suppress wasteful fuel consumption and emission of exhaust gas while the vehicle is stopped. Engine stop conditions in such an idle stop vehicle include vehicle stop and brake ON, and engine restart conditions include brake OFF and accelerator pedal depression.

  In the idling stop vehicle as described above, an oil pump driven by the engine, a belt-type continuously variable transmission whose output shaft is connected to a drive wheel, and a starting clutch provided between the engine and the continuously variable transmission And a hydraulic control device that supplies hydraulic pressure to the continuously variable transmission and the 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 pressure supplied to the continuously variable transmission and the starting clutch is lost during the idle stop. For this reason, if the start clutch is engaged early in an attempt to start from the idle stop state, there is a problem that the belt clamping pressure of the continuously variable transmission is insufficient and slip occurs between the belt and the pulley.

  FIG. 7 shows an example of conventional engagement control of the starting clutch at the time of idle stop return (engine restart). When the idle stop returns at time t1, the engine speed starts to increase due to cranking, and the turbine speed starts to increase as the engine starts. The starting clutch is supplied with a clutch pressure so as to achieve a target clutch transmission torque corresponding to the initial pressure, and the secondary pulley is supplied with a hydraulic pressure for generating a belt clamping pressure. The initial pressure is a hydraulic pressure for starting the engagement of the starting clutch, and is set to, for example, a hydraulic pressure corresponding to the return spring force of the piston in the starting clutch. Since the engine starts to rotate spontaneously at time t2 when the cranking period ends, the engine speed rapidly increases, and the turbine speed also increases. When the supply of the initial pressure is completed at time t3, the pressure increase control (sweep control) is started with a certain time gradient from the initial pressure. The clutch transmission torque gradually increases with the boost control, and the turbine speed decreases. After the turbine rotational speed becomes substantially 0 (synchronous detection), the starting clutch is completely engaged at time t4.

  Immediately after the idling stop return as described above, since the discharge pressure of the oil pump itself is low, it takes time to fill the hydraulic oil in the pulley oil chamber of the continuously variable transmission, resulting in a delay in the increase of the belt clamping pressure, The increase in belt transmission torque is also delayed. On the other hand, although the hydraulic pressure with the initial pressure as the target value is also supplied to the starting clutch, the actual clutch transmission torque does not immediately rise to the torque corresponding to the initial pressure. If the clutch transmission torque of the starting clutch exceeds the belt transmission torque of the continuously variable transmission as shown by the hatched lines in FIG. 7, belt slippage occurs and the durability of the belt is reduced.

  In Patent Document 1, the in-gear state of the power transmission mechanism (the state in which power can be transmitted) is detected from the rotational speed of the drive pulley of the continuously variable transmission at the time of start after returning from the idle stop, and the control mode of the start clutch is set to Before detecting the state, switch to the standby mode that keeps the engaging force of the starting clutch below the creep force of the vehicle, and after detecting the in-gear state, switch to the driving mode that raises the engaging force of the starting clutch above the creep force and after switching to the driving mode The predetermined time is disclosed to limit the rate of increase of the engaging force of the starting clutch.

  Patent Document 2 discloses a predetermined timing from engine restart without starting engagement of the start clutch even if it is determined that the hydraulic pressure is sufficiently generated to start engagement of the start clutch at engine restart after idle stop. A system is disclosed in which the fastening is started after waiting for a predetermined time until it becomes.

  In the case of Patent Document 1, since the start clutch is provided on the downstream side (drive wheel side) of the continuously variable transmission, belt slip immediately after the return to idle stop is achieved by setting the engagement force of the start clutch to be the creep force or less. Although it can be eliminated, belt slip cannot be eliminated in the case of a vehicle that does not have a starting clutch downstream from the continuously variable transmission. Patent Document 1 relates to prevention of belt slippage after the in-gear state, and does not consider prevention of belt slipping in the out-gear state immediately after the return to idle stop.

  Patent Document 2 relates to the control of the starting clutch upstream of the belt-type continuously variable transmission, but the starting clutch engagement control is not started until a predetermined time elapses after the belt clamping pressure reaches a predetermined level. . That is, since the start clutch is not controlled until the predetermined time elapses, there is a concern that belt slippage may occur if unintended hydraulic pressure is supplied to the start clutch during that period.

JP 2001-90757 A JP 2007-24129 A

  An object of the present invention is to provide a start clutch control device for an idle stop vehicle that can prevent belt slippage at the time of return to idle stop in a vehicle having a start clutch upstream of a continuously variable transmission.

  To achieve the above object, the present invention provides an engine that is automatically stopped when a predetermined condition is satisfied, an oil pump that is driven by the engine, and 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 that supplies hydraulic pressure to the continuously variable transmission and the starting clutch based on a hydraulic pressure generated by the oil pump; A belt clamping pressure detecting means for detecting a belt clamping pressure of the continuously variable transmission, and a transmission torque calculation for calculating a belt transmission torque of the continuously variable transmission from the detected belt clamping pressure. When the engine is restarted from an automatic stop state, belt slippage of the continuously variable transmission is not generated as engagement control of the starting clutch. Control means for sequentially performing belt slip prevention control for supplying clutch pressure and pressure increase control for increasing the clutch pressure with a predetermined time gradient, wherein the target clutch pressure of the starting clutch is a predetermined value. Until the clutch transmission torque of the starting clutch does not exceed the calculated belt transmission torque, the clutch pressure is controlled so as to be a target clutch pressure corresponding to the belt transmission torque, Provided is a start clutch control device for an idle stop vehicle, wherein the clutch pressure is controlled according to a target clutch pressure that rises with a predetermined time gradient after the target clutch pressure reaches a predetermined value.

  In the present invention, at the time of low oil pressure immediately after the return to idle stop, the belt slip prevention control for supplying the clutch pressure that does not cause the belt slip is performed instead of supplying the predetermined initial pressure as the target clutch pressure to the starting clutch. . This belt slip prevention control is to control the clutch pressure so that the clutch transmission torque of the starting clutch does not exceed the belt transmission torque of the continuously variable transmission so that the target clutch pressure according to the belt transmission torque is obtained. In other words, the upper limit value of the target clutch pressure may be set to a hydraulic pressure corresponding to the belt transmission torque. Therefore, it is possible to eliminate a situation in which the starting clutch is engaged early when the idle stop is restored, the belt clamping pressure of the continuously variable transmission is insufficient, and slippage occurs between the belt and the pulley. The belt transmission torque rapidly increases when the hydraulic oil is filled in the pulley oil chamber of the continuously variable transmission, but when the target clutch pressure is also increased following the belt transmission torque, a sudden engagement shock is generated. Therefore, the belt slip prevention control is performed only until the target clutch pressure reaches a predetermined value, and after the target clutch pressure reaches the predetermined value, the pressure increase control may be performed in the same manner as the normal engagement control.

  The method for calculating the belt transmission torque is arbitrary. For example, the hydraulic pressure sensor may detect the hydraulic pressure of the secondary pulley of the continuously variable transmission, calculate the belt clamping pressure from the detected hydraulic pressure, and then calculate the belt transmission torque from the belt clamping pressure. As another method, the belt clamping pressure of the primary pulley is estimated from the belt clamping pressure of the secondary pulley and the operation status, and the belt transmission torque is obtained from the smaller one of the belt clamping pressures of both pulleys. Also good.

  If the elapsed time from the engine restart until the target clutch pressure reaches the predetermined value (the period of belt slip prevention control) is shorter than the predetermined time, the target clutch pressure is held at the predetermined value until the predetermined time is reached. May be. In other words, the belt slip prevention control period varies depending on the rate of increase of the belt transmission torque, but when this period is shorter than the initial pressure supply period in normal clutch control, the clutch slip pressure is simultaneously with the end of the belt slip prevention control. When the pressure increase control is started, there is a possibility that the clutch is engaged too early and a shock occurs. Therefore, when the belt slip prevention control period is shorter than the predetermined time, the target clutch pressure is preferably maintained at a predetermined value (for example, initial pressure) until the predetermined time is reached. If it does in this way, the shock and time lag at the time of start can be optimized.

  When the initial pressure is used as an example of the predetermined value, the initial pressure supply period may be constant, but may be increased as the hydraulic oil temperature decreases. In other words, when the hydraulic oil temperature is low, the rise of the hydraulic pressure tends to be delayed due to the viscous resistance of the oil, so by setting the initial pressure supply period longer along with the lowering of the hydraulic oil temperature, Even at times, the invalid stroke of the piston can be eliminated and the occurrence of shock can be suppressed. In addition, the initial pressure supply period may vary depending on factors other than the oil temperature.

  As described above, according to the present invention, the target clutch pressure of the starting clutch is set low so that the clutch transmission torque of the starting clutch does not exceed the belt transmission torque of the continuously variable transmission when starting after returning from idle stop. The problem of slippage between the belt and the pulley of the continuously variable transmission can be solved when the idle stop is restored.

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 the detail of a garage shift valve. It is a figure which shows each characteristic of line pressure P _{L with} respect to solenoid pressure Psls, clutch modulator pressure Pcm, clutch control pressure, and secondary pressure. It is a time chart figure of an example of engagement control of a starting clutch at the time of idle stop return concerning the present invention. It is a flowchart figure of an example of the target hydraulic pressure determination method for engagement control of the starting clutch which concerns on this invention. It is a time chart figure of an example of starting clutch control at the time of the conventional idling stop return.

  FIG. 1 shows an example of the configuration of an idle stop vehicle according to the present invention. An output shaft 1 a of the engine 1 is connected to a drive shaft (output shaft) 32 via a 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 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) 85, and a direct clutch (C1) 86, and the reverse brake 85 or the direct clutch 86 corresponds to the starting clutch in the present invention. The reverse brake 85 and the direct coupling clutch 86 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 85 is provided between the carrier 84 supporting the pinion gear 83 and the transmission case, and the direct coupling clutch 86 is provided between the carrier 84 and the sun gear 81. When the direct coupling clutch 86 is released and the reverse brake 85 is engaged, the rotation of the turbine shaft 5 is reversed, 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. Conversely, when the reverse brake 85 is released and the direct clutch 86 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 CVT hydraulic oil temperature sensor 107, and the hydraulic pressure sensor 108 that detects the hydraulic pressure supplied to the secondary pulley 21. 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 vehicle is stopped and a predetermined condition is satisfied, and restarts the engine 1 when the predetermined condition is not satisfied. To do. As a condition for permitting the idle stop, for example, there is a brake ON (depressing the brake pedal). However, idling stop is not permitted when the engine water temperature is low, the electric load is large, or the accelerator pedal is depressed. On the other hand, idle stop release (engine restart) conditions include, for example, brake OFF, accelerator pedal depression, and input of a vehicle speed signal. Since the idle stop permission condition and the release condition are known, detailed description thereof 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 oil chamber 13 of the primary pulley 11, the oil chamber 23 of the secondary pulley 21, the reverse brake 85, and the direct coupling clutch 86, respectively. The electronic control unit 100 determines the target primary rotational speed according to a shift map set in advance according to the vehicle speed and the throttle opening, and controls the solenoid valve in the hydraulic control unit 7 to thereby control the continuously variable transmission 2. The oil amount / hydraulic pressure of the oil chambers 13 and 23 of the primary pulley 11 and the secondary pulley 21 is adjusted to control the primary rotational speed to the target value, and the belt clamping pressure of the secondary pulley 21 is set to a value that does not cause belt slip. I have control. The hydraulic control device 7 also has a function of controlling the hydraulic pressure supplied to the reverse brake 85 and the direct coupling clutch 86, and this control includes the engagement control of the reverse brake (starting clutch) 85 from an idle stop state to be described later. 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 SLS outputs the solenoid pressure Psls in order to perform pressure regulation control of the line pressure, transient control of the reverse brake 85 (B1) and the direct coupling clutch 86 (C1), and pressure regulation control of the oil chamber 23 of the secondary pulley 21. A pressure regulating solenoid valve, DS1 is an upshift solenoid valve for regulating the pressure of the upshift signal pressure Pds1, and DS2 is a downshift solenoid valve for regulating the pressure of the downshift signal pressure Pds2. In the present embodiment, the 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 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 are supplied with and discharged into the oil chamber 12 of the primary pulley 11 by the relative relationship between the upshift signal pressure Pds1 and the downshift signal pressure Pds2. It is a valve that adjusts. Further, the ratio check valve 78 switches the oil chamber 12 of the primary pulley 11 from the flow rate control to the hydraulic control for closing control so that the oil pressure of the oil chamber 12 of the primary pulley 11 and the oil chamber 23 of the secondary pulley 21 are controlled. It is a valve for maintaining the ratio with the hydraulic pressure in a preset 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 valve for controlling the hydraulic pressure of the hydraulic oil chamber 23 of the secondary pulley 21 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 hydraulic oil chamber 23 of the secondary pulley 21, 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 hydraulic oil chamber 23. The hydraulic pressure supplied to the hydraulic oil chamber 23 is detected by the hydraulic pressure sensor 108, and the belt transmission torque can be obtained based on the detected hydraulic pressure.

  The garage shift valve 74 is for switching the oil path 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 to D or from N to R (in garage shift). It is a switching valve. FIG. 3 shows the detailed structure of the garage shift valve 74. The left side of the center line is a transient state and the right side is a holding state. A spool 74b is inserted into the valve body 74a so as to be movable in the axial direction, and a spring 74c for urging the spool 74b in one direction is provided at one end. One end of the valve body 74a is provided with signal ports 74d and 74e to which the upshift signal pressure Pds1 and the downshift signal pressure Pds2 are input in the same direction as the spring load. On the other end side of the valve body 74a, a counter port 74f to which the solenoid modulator pressure Psm is input in a direction opposite to the spring load is provided. The pressure receiving area of the spool 74b in the counter port 74f is set equal to the sum of the pressure receiving areas of the spool 74b in the signal ports 74d and 74e to which the signal pressures Pds1 and Pds2 are input. An intermediate part of the valve body 74a includes an input port 74g to which the clutch modulator pressure Pcm is input, an input port 74h to which the solenoid pressure Psls is input, and an output port 74i connected to the input port 75a of the manual valve 75. Is provided.

  Here, the operation of the garage shift valve 74 will be described. First, the operation when the shift lever is switched from N → D or N → R (in garage shift) will be described. At N, the solenoid modulator pressure Psm is supplied to the counter port 74f, and at least one of the solenoid valves DS1 and DS2 is turned OFF, so that at least one of the signal pressures Pds1 and Pds2 is drained. Therefore, the garage shift valve 74 overcomes the spring load by the solenoid modulator pressure Psm and is positioned at the holding position. When switching from N → D or N → R, both solenoid valves DS1 and DS2 are turned on, so that the signal pressures Pds1 and Pds2 of the solenoid valves DS1 and DS2 supplied to the ports 74d and 74e and the counter port 74f are supplied. The solenoid modulator pressure Psm is balanced. Since the spring load acts in the same direction as the signal pressures Pds1 and Pds2, the spool 74b is switched to the transient position on the left side of the center line in FIG. For this reason, the solenoid pressure Psls that rises gently by the solenoid valve SLS is supplied to the direct clutch C1 or the reverse brake B1 via the ports 74h and 74i and the manual valve 75, while avoiding the engagement shock of the direct clutch C1 or the reverse brake B1. Engagement can be performed.

  When the solenoid pressure Psls controlled by the solenoid valve SLS rises to the required oil pressure (the engagement state of the direct coupling clutch C1 or the reverse brake B1), at least one of the signal pressures Pds1 and Pds2 is drained by the solenoid valves DS1 and DS2. Due to the action of the solenoid modulator pressure Psm supplied to the counter port 74f, the garage shift valve 74 is switched to the holding position on the right side of the center line in FIG. As a result, the clutch modulator pressure Pcm, which is the original pressure of the solenoid pressure Psls, is supplied to the direct coupling clutch C1 or the reverse brake B1 via the ports 74g and 74i and the manual valve 75. Therefore, the engaged state of the direct clutch C1 or the reverse brake B1 can be maintained regardless of the operation of the solenoid valve SLS.

  Since the discharge pressure of the oil pump 6 is low when the engine is started after the idle stop is released, the solenoid modulator pressure Psm is supplied to the counter port 74f in a low pressure state, while the signal pressures Pds1 and Pds2 from the solenoid valves DS1 and DS2 are also supplied. The low pressure state is supplied to the ports 74d and 74e. Here, both solenoid valves DS1 and DS2 are in the ON (fully open) state. In this state, the garage shift valve 74 is held at the transient position on the left side of the center line in FIG. 3 by the urging force of the spring 74c. Thereafter, when the solenoid modulator pressure Psm rises to the normal pressure, the signal pressures Pds1 and Pds2 are also in the normal pressure state at the same time, so that the garage shift valve 74 is held at the left transient position even in the normal pressure state. Since the solenoid pressure Psls controlled by the solenoid valve SLS is supplied to the direct clutch C1 or the reverse brake B1 via the manual valve 75, the transmission torque capacity of the direct clutch C1 or the reverse brake B1 can be finely controlled.

  After the solenoid pressure Psls rises to the required oil pressure, the garage shift valve 74 is switched to the holding position and the clutch modulator pressure Pcm is directly connected to the clutch C1 via the manual valve 75, as in the case of N → D or N → R. Or it is supplied to the reverse brake B1.

  As described above, when the solenoid modulator pressure Psm is supplied in the low pressure state immediately after the idle stop is released, the garage shift valve 74 of the present embodiment also reduces the signal pressures Pds1 and Pds2 from the solenoid valves DS1 and DS2. Therefore, when the solenoid modulator pressure Psm rises to the normal pressure, the signal pressures Pds1 and Pds2 are also in the normal pressure state at the same time. Therefore, even in this normal pressure state, the garage shift valve 74 is in the normal pressure state. Held in a transient position. Therefore, the solenoid pressure Psls controlled by the solenoid valve SLS is supplied to the reverse brake B1 or the direct clutch C1, and the transmission torque capacity of the reverse brake B1 or the direct clutch C1 is set so as not to exceed the belt transmission torque capacity by the solenoid pressure Psls. By controlling, belt slippage can be prevented.

FIG. 4 shows the 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 controlled to a constant pressure when the pressure 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.

  Here, the engagement control of the starting clutch (B1) at the time of idle stop return (engine restart) in the present invention will be described with reference to FIG. FIG. 5 shows the clutch hydraulic pressure and the belt clamping pressure, both of which can be controlled by the solenoid valve SLS. The belt transmission torque can be calculated based on the oil pressure in the oil chamber 23 of the secondary pulley 21 detected by the oil pressure sensor 108.

  For example, in the D range, when the idle stop is restored at time t1, the engine speed starts to increase due to cranking, and the torque converter 3 is also dragged by the engine start to increase in rotation. Subsequently, the belt transferable torque of the secondary pulley 21 is calculated based on the secondary clamping pressure detected by the hydraulic pressure sensor 108, and a target clutch pressure corresponding to the belt slip guarantee target hydraulic pressure is set. And an actual clutch pressure is controlled so that it may become a target clutch pressure with respect to a starting clutch. The target clutch pressure is set so as not to exceed the calculated belt transmission torque, and is specifically set to a hydraulic pressure that generates a clutch transmission torque that is lower than the belt transmission torque by a certain amount or a certain ratio. Therefore, it is possible to avoid a situation where the belt slip occurs due to the clutch transmission torque of the starting clutch exceeding the belt transmission torque of the continuously variable transmission.

  At the time t2 when the cranking period ends, the engine speed rapidly rises and the turbine speed also rises following, but begins to deviate from the engine speed. When the target clutch pressure rises to a predetermined value corresponding to the initial pressure around time t2, after time t2, the clutch hydraulic pressure of the starting clutch is not the target clutch pressure corresponding to the belt slip guarantee target hydraulic pressure but the predetermined pressure corresponding to the initial pressure. The value is held to suppress a sudden increase in clutch transmission torque.

  When the supply of the initial pressure is completed at time t3, the pressure increase control (sweep control) is started with a certain time gradient from the initial pressure. The clutch transmission torque gradually increases with the boost control, and the turbine speed decreases. After the turbine rotational speed becomes substantially 0 (synchronous detection), the starting clutch is completely engaged at time t4.

  In the control, after the target clutch pressure has increased to a predetermined value at time t2, the pressure is not immediately shifted to the pressure increase control but is maintained at a predetermined value corresponding to the initial pressure until time t3. This is the case where the period is shorter than the normal initial pressure supply period T0. If the increase in the belt clamping pressure is slow and the period from t1 to t2 is longer than the normal initial pressure supply period T0, from time t2. You may transfer to boost control immediately. In addition, after the target clutch pressure rises to a predetermined value, a predetermined time may be awaited when shifting to the pressure increase control, or a condition that the CVT original pressure (line pressure) is a certain value or more may be added. . In this case, it is possible to cope with variations in oil temperature, idle stop time, clutch characteristics, and the like. Note that when the engine torque immediately after the return to idle stop is excessive, the starting clutch slip time becomes longer, and the reduction of the slip time can be dealt with by engine torque-down control.

  In this example, since the turbine rotational speed is not detected, the initial pressure supply period (t1 to t3) is set to a predetermined period corresponding to the oil temperature. However, when the turbine rotational speed is detected, the turbine rotational speed is detected. The time point when the number starts to deviate from the engine speed (out of synchronization) may be set as the initial pressure supply end point.

  FIG. 6 is a flowchart showing a starting clutch engagement control at the time of idling stop return, particularly a method for determining a target clutch oil pressure. When starting, first, the hydraulic pressure of the secondary pulley 21 is detected by the hydraulic pressure sensor 108 (step S1), the secondary clamping pressure is calculated from the secondary pressure and the pressure receiving area (step S2), and the secondary clamping pressure and friction with the belt are further calculated. The secondary transmission torque is calculated from the coefficient, the winding diameter, etc. (step S3). On the other hand, the primary clamping pressure and the primary transmission torque are estimated or calculated from the detected secondary pressure using a preset map (steps S4 and S5). For example, this map shows the relationship between the secondary pressure and the primary pressure when the gear ratio is at the lowest level, experimentally investigated the influence of variations in transmission specifications, oil temperature, etc., and the primary pressure is within the range where belt slip does not occur. Create under the lowest conditions. Then, the primary pressure corresponding to the detected secondary pressure is selected from the map, the primary clamping pressure is obtained from the primary pressure and the pressure receiving area (step S4), and further, the primary transmission is determined from the friction coefficient with the belt, the winding diameter, and the like. Torque is calculated (step S5).

  Next, the smaller one of the calculated secondary transmission torque and primary transmission torque is selected (step S6). A belt slip guarantee target hydraulic pressure for the starting clutch is calculated from the smaller transmission torque (step S7). On the other hand, a target hydraulic pressure for clutch engagement control at that time is obtained (step S8). This target hydraulic pressure may be a hydraulic pressure corresponding to the initial pressure until time t3.

  Next, the smaller one of the belt slip guarantee target hydraulic pressure and the clutch engagement control target hydraulic pressure is selected (step S9), and this is set as the final target hydraulic pressure (step S10). Therefore, if the clutch hydraulic pressure is controlled using the final target hydraulic pressure as a target value, a situation in which the clutch transmission torque of the starting clutch exceeds the belt transmission torque of the continuously variable transmission can be avoided, and belt slip can be prevented.

  In the above embodiment, in order to obtain the belt slip guarantee target hydraulic pressure (target clutch transmission possible torque), the smaller one is selected by comparing the secondary clamping pressure and the primary clamping pressure. However, the present invention is not limited to this method. For example, the belt slip guarantee target hydraulic pressure may be determined using only the secondary clamping pressure obtained from the detection result of the hydraulic sensor.

  In the above-described embodiment, the case where the start clutch is the reverse brake (B1) 85 has been described as an example in order to start forward travel when returning to idle stop. However, when starting reverse travel, the start clutch is a direct clutch. (C1) 86.

  The hydraulic circuit of the starting clutch is not limited to those shown in FIGS. In particular, when starting at the same time as returning from the idle stop, the configuration is arbitrary as long as it can supply hydraulic pressure substantially proportional to the command current to the solenoid valve to the starting clutch. FIG. 2 shows an example in which the clamping control of the secondary pulley 21 and the engagement control of the start clutch 85 are performed using the common solenoid valve SLS. However, the present invention is not limited to this. The hydraulic control of both may be performed using

DESCRIPTION OF SYMBOLS 1 Engine 2 Continuously variable transmission 3 Torque converter 4 Continuously variable transmission 5 Turbine shaft 6 Oil pump 7 Hydraulic control device 8 Forward / reverse switching 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 Ratio control valve for upshift 77 Ratio control valve for downshift 78 Ratio check valve 79 Nipping control valve 80 Planetary gear mechanism 85 (B1) Reverse brake (starting clutch)
86 (C1) Direct coupling clutch 100 Electronic control unit 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 SLS Solenoid valve DS1 Solenoid valve DS2 Solenoid valve

Claims (2)

An engine that automatically stops when a predetermined 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;
In an idle stop vehicle comprising: a continuously variable transmission and a hydraulic control device that supplies hydraulic pressure to the starting clutch based on the hydraulic pressure generated by the oil pump;
Belt clamping pressure detecting means for detecting 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;
When the engine is restarted from the automatic stop state, as the engagement clutch control, a belt slip prevention control that supplies a clutch pressure that does not cause belt slip of the continuously variable transmission, and a clutch pressure with a predetermined time gradient. Control means for sequentially performing boosting control for raising
The belt slip prevention control is performed so that the clutch transmission torque of the starting clutch does not exceed the calculated belt transmission torque until the target clutch pressure of the starting clutch reaches a predetermined value. Control the clutch pressure so that it becomes the clutch pressure,
The start-up control is a start clutch control device for an idle stop vehicle, wherein the boost control controls the clutch pressure according to a target clutch pressure that rises with a predetermined time gradient after the target clutch pressure reaches a predetermined value.   When the elapsed time from the restart of the engine until the target clutch pressure reaches a predetermined value is less than a predetermined time, the target clutch pressure is maintained at the predetermined value until the predetermined time is reached. The start clutch control device for an idle stop vehicle according to claim 1.

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