JP2011133013A - Controller for continuously variable transmission for idling stop vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a continuously variable transmission for an idling stop vehicle, which overcomes the problem of air intrusion into a primary oil chamber generated before idling stop. <P>SOLUTION: Air flows in sometimes when draining a hydraulic fluid from the primary oil chamber before the idling stop, for bringing the idling stop while stopping a vehicle from a deceleration state. The hydraulic oil is filled quickly into the primary oil chamber until stopping an engine after determining the idling stop, to discharge the air flowing into the primary chamber. Then, a response delay of belt clamping pressure is prevented when the idling stop is restored (the engine is restarted up), preventing a belt from slipping. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a control device for a continuously variable transmission for an idle stop vehicle, and more particularly to a device for controlling the supply of hydraulic oil to a primary pulley oil chamber of a belt type continuously variable transmission.

2. Description of the Related Art In recent years, an idle stop vehicle has been attracting attention because it automatically stops the engine when the vehicle is stopped, thereby suppressing wasteful fuel consumption and exhaust gas generation while the vehicle is stopped. In such an idle stop vehicle, an oil pump driven by an engine, a belt-type continuously variable transmission that transmits engine power to driving wheels, and a hydraulic pressure supplied to the continuously variable transmission based on the hydraulic pressure generated by the oil pump There is a vehicle including a hydraulic control device that controls the vehicle. The continuously variable transmission includes a primary pulley and a secondary pulley each having a pulley oil chamber, and a belt is wound between the pulleys.

Generally, in a continuously variable transmission, by controlling the hydraulic pressure supplied to the secondary oil chamber with a solenoid valve, the belt clamping pressure is controlled, and by controlling the flow rate of hydraulic oil to the primary oil chamber with another solenoid valve, The pulley ratio is controlled. However, in the idle stop vehicle, the oil pump is also stopped along with the idle stop, so that the hydraulic pressure supplied to the continuously variable transmission disappears. Therefore, the following problems may occur.

In general, when the vehicle is stopped from the deceleration state, it is necessary to return the pulley ratio of the continuously variable transmission to the maximum gear ratio (lowest) state before the vehicle stops, so that the hydraulic oil is discharged from the primary oil chamber. However, just before the vehicle stops (for example, 3 km / h or less), the detection accuracy of the pulley ratio deteriorates and it cannot be detected whether the pulley ratio has returned to the lowest state, so the lowest state is reached to ensure the lowest state. After that, hydraulic oil continues to be discharged from the primary oil chamber. Until the pulley ratio reaches the lowest level, the hydraulic oil in the primary oil chamber is drained via the ratio control valve controlled by the drain solenoid valve. When the pulley ratio reaches the lowest level, the movable sheave of the primary pulley acts as a stopper. Because of the contact, the volume change of the pulley oil chamber is eliminated. Therefore, after reaching the lowest level, air corresponding to the volume of the hydraulic oil discharged from the pulley oil chamber flows into the pulley oil chamber through the seal portion.

When air (air is a compressive fluid) flows into the primary oil chamber in this way, even if an attempt is made to increase the primary hydraulic pressure when returning to idle stop (engine restart), the pressure increase is delayed, and the belt is transmitted transiently. Since the torque is reduced, there is a risk of belt slippage.

Conventionally, in order to prevent the hydraulic pressure in the primary oil chamber from escaping when the vehicle stops at the lowest level (or at the very low vehicle speed immediately before and immediately after stopping), the supply of hydraulic oil to the primary oil chamber is performed at a flow rate. Switching from control to pressure control (so-called confinement control). However, in the case of an idle stop vehicle, the closing control is performed only during the period until the engine is automatically stopped, so the time is short, and the supply oil path to the primary oil chamber during the closing control is set to the closing control. Since a small-diameter orifice is set in order to prevent a sudden speed change at the time of switching, the air flowing into the primary oil chamber does not escape and the above problem becomes apparent.

FIG. 7 shows an example of conventional control when the vehicle stops from the deceleration state and the engine is automatically stopped after the idle stop determination. The vehicle speed, the ratio (pulley ratio), the engine speed, the shift control solenoid valve DS1. , DS2 operation and primary oil pressure change over time. DS1 is a solenoid valve for filling the primary oil chamber, and DS2 is a solenoid valve for the drain side. In the primary hydraulic pressure, a solid line indicates a change in hydraulic pressure when air does not flow in, and a broken line indicates a change in hydraulic pressure when air flows in.

t1 is a time point when the vehicle is decelerated to a predetermined vehicle speed (for example, 5 km / h) or less and the pulley ratio reaches the lowest level. Eventually, the vehicle stops, and at time t2, both the charging side and drain side solenoid valves DS1, DS2 are turned OFF, and the closing control is started. Subsequently, at time t3, it is determined that idle stop is performed, that is, a predetermined engine stop condition is satisfied. Thereafter, the engine is stopped at time t4, and if a predetermined engine return condition is satisfied at time t5, the engine is restarted. When reaching the lowest level (t1), the primary hydraulic pressure may be completely removed and air may begin to flow in. In particular, if the period from t1 to t2 becomes longer, air tends to flow into the primary oil chamber. When air is not flowing in, as shown by the solid line, the primary hydraulic pressure is quickly increased with the start of the closing control, but when air is flowing in, the pressure increase is delayed as indicated by the broken line. Moreover, since the orifice is provided in the supply oil passage, the hydraulic oil may not be filled and the inflowing air may not be discharged. Eventually, when the engine is stopped at time t4, the oil pump is also stopped, so that the filling of hydraulic oil is stopped. When the engine is restarted by returning to idle stop at time t5, air remains in the primary oil chamber, and the pressure increase of the primary hydraulic pressure is delayed, causing belt slip. Further, since the transmission of the driving force is delayed at the time of idling stop return, the starting performance at the time of restart is deteriorated.

In Patent Document 1, in an idle stop vehicle having a belt-type continuously variable transmission having a mechanical oil pump, the discharge of hydraulic oil during idle stop is regulated, and the hydraulic oil in the transmission is stopped even if the oil pump stops. A control device that suppresses a decrease in hydraulic pressure is disclosed. In Patent Document 2, hydraulic oil is supplied to a primary oil chamber of a belt-type continuously variable transmission in a non-running shift state while the vehicle is stopped, and a shift delay at the time of start due to the release of hydraulic oil (air entry) is prevented. Is disclosed.

Patent Document 1 only regulates the discharge of hydraulic oil during idle stop, and cannot solve the problem of air entering the primary oil chamber that occurs before idle stop. Patent Document 2 is intended to solve the problem caused by the air entering the primary oil chamber, but is intended for engine start after being left for a long period of time, and a specific application to idle stop control is disclosed. Absent.

JP 2001-41315 A JP-A-10-259865

An object of the present invention is to provide a control device for a continuously variable transmission for an idle stop vehicle that can solve the air entering the primary oil chamber that occurs before the idle stop.

In order to achieve the above object, the present invention provides an engine, an idle stop control means for performing an idle stop execution determination when a predetermined stop condition is satisfied, and then automatically stopping the engine, and an oil driven by the engine A belt-type continuously variable transmission having a pump, a primary pulley and a secondary pulley and transmitting engine power to driving wheels; and a primary pulley and a secondary of the continuously variable transmission based on a hydraulic pressure generated by the oil pump A hydraulic control device for controlling the hydraulic pressure supplied to the pulley; an engine speed detecting means for detecting the engine speed; a vehicle speed detecting means for detecting the vehicle speed; and a pulley ratio for detecting the pulley ratio of the continuously variable transmission. In the idle stop vehicle having the detection means, the hydraulic control device changes the pulley ratio to the maximum before the vehicle stops. The control to complete the ratio and complete the control to discharge the hydraulic oil from the primary pulley even after reaching the maximum gear ratio. When the idle stop control means makes an idle stop execution determination after the vehicle stops, A control device for a continuously variable transmission for an idle stop vehicle, characterized in that hydraulic oil is rapidly filled into a primary pulley for a predetermined period of time.

When the vehicle is stopped from the deceleration state and the engine is automatically stopped, if the time from reaching the maximum gear ratio to the start of the closing control is long, air may flow into the primary oil chamber during that time. Therefore, between the idle stop execution determination and the engine stop, the primary oil chamber is rapidly filled with the working oil and the inflowing air is forcibly discharged. By discharging the air that flows in before the idle stop operation from the primary oil chamber in this way, the hydraulic pressure in the primary oil chamber rises quickly when the engine is restarted, eliminating the delay in boosting the belt clamping pressure, thus preventing belt slippage. Can be prevented. In addition, since the engine driving force can be transmitted promptly at the time of idling stop return, the starting performance at the time of restart can be improved.

The hydraulic control unit receives the ratio control valve that controls the flow rate of hydraulic oil to the primary pulley, the solenoid valve that generates the signal pressure that operates the ratio control valve, and the hydraulic pressure of the secondary pulley as the signal pressure. When a ratio check valve that controls oil pressure and an orifice provided in an oil passage connecting the ratio check valve and the primary pulley are provided, the pulley ratio is set to the maximum gear ratio state before the vehicle stops. The hydraulic oil of the primary pulley is discharged by the ratio control valve, and when the vehicle is stopped or just before that, the hydraulic oil to the primary pulley is pressure controlled by the ratio check valve instead of the ratio control valve to maintain the maximum gear ratio state. When the idle stop control means makes an idle stop execution determination after the vehicle stops, It may be rapidly filled with the working oil to the primary pulley by Jin automatic stop immediately before the predetermined time only instead of the ratio check valve ratio control valve. In this way, the hydraulic pressure is not supplied via the orifice as in the closing control (pressure control by the ratio check valve), but the line pressure is supplied to the primary oil chamber by the ratio control valve without going through the orifice. It becomes possible to fill. The operation period of the ratio control valve for rapid filling may be any time as long as it is during the period from the idle stop execution determination to the engine stop.

As described above, according to the present invention, even if air flows into the primary oil chamber when the vehicle is stopped from the deceleration state and the engine is automatically stopped, the primary oil is determined between the idle stop determination and the engine stop. Since the chamber is rapidly filled with the hydraulic oil and the inflowing air is discharged, the response delay of the belt clamping pressure at the time of idling stop return (engine restart) can be eliminated, and the occurrence of belt slip can be prevented. Further, since the driving force can be transmitted promptly at the time of idling stop return, the starting performance at the time of restart can be improved.

It is a skeleton figure which shows the structure of the vehicle which concerns on this invention. It is a detailed sectional view of a primary pulley and a secondary pulley. FIG. 2 is a hydraulic circuit diagram of the hydraulic control device for the continuously variable transmission shown in FIG. 1. It is a hydraulic circuit diagram of the principal part of FIG. 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 figure which shows each time change of the vehicle speed, ratio, engine speed, solenoid valve, and primary oil pressure at the time of idle stop which concerns on this invention. It is a figure which shows each time change of the vehicle speed, ratio, engine speed, solenoid valve, and primary hydraulic pressure at the time of the conventional idle stop.

FIG. 1 shows an example of the configuration of a vehicle equipped with a continuously variable transmission 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 a known compression drive type metal belt.

The forward / reverse switching device 8 includes a planetary gear mechanism 80, a reverse brake B1, and a direct coupling clutch C1. 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, decelerated and transmitted to the primary shaft 10, and the drive shaft 32 passes through the secondary shaft 20 in the same direction as the engine rotation direction. Since it rotates, it will be in a forward running state. Conversely, 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, and the drive shaft 32 passes through the secondary shaft 20. Rotates in the direction opposite to the engine rotation direction, so that the vehicle travels backward.

FIG. 2 shows a specific structure of the transmission 4. The primary pulley 11 includes a fixed sheave 11a integrally formed on the primary shaft 10, and a movable sheave 11b supported on the primary shaft 10 so as to be axially movable and integrally rotatable. 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. Hydraulic oil is supplied to the oil chamber 13 from an oil passage 41 provided in the transmission case 40 through the axial hole 10 a of the primary shaft 10. Shift control is performed by controlling the flow rate of this hydraulic oil with ratio control valves 76 and 77 described later. A seal 42 is provided at a connection portion between the oil passage 41 and the axial hole 10a.

The secondary pulley 21 includes a fixed sheave 21a formed integrally on the secondary shaft 20, and a movable sheave 21b 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 (secondary pressure) supplied to the oil chamber 23, a belt clamping pressure necessary for torque transmission is applied. In addition, a bias spring 24 for providing an initial clamping pressure is disposed in the oil chamber 23. In the supply oil passage in the vicinity of the oil chamber 23 of the secondary pulley 21, a hydraulic pressure sensor 108 (see FIG. 3) for detecting the secondary pressure is provided.

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 continuously variable transmission 2 is controlled by an electronic control unit 100 (see FIG. 1). 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 sensor 105, a brake signal. Detection signals are input from the sensor 106, the hydraulic oil temperature sensor 107 of the CVT, and the hydraulic pressure sensor 108 that detects the secondary pressure. Of course, other signals may be input as the input signal. The pulley ratio can be detected based on detection signals from the primary pulley rotation speed sensor 105 and the vehicle speed sensor 102. The electronic control unit 100 is linked to an engine control ECU (not shown), and an idle stop execution determination signal is input from the engine control ECU. The idle stop execution determination condition (engine stop condition) includes vehicle speed 0, accelerator off, brake on, and the like, and the engine restart condition (return condition) includes brake off, accelerator on, and the like.

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 B1, and the direct coupling clutch C1. 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. Adjust the oil amount / hydraulic pressure of the oil chambers 13 and 23 of the primary pulley 11 and the secondary pulley 21 to control the primary rotational speed to a target value and control the belt clamping pressure to a target value that does not cause belt slip. Yes. 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.

FIG. 3 is a hydraulic circuit diagram of an example of the hydraulic control device 7, and FIG. 4 is a hydraulic circuit diagram of the main part thereof. 3, 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, SLS is a linear solenoid valve that outputs a solenoid pressure Psls for performing pressure regulation control of the line pressure, transient control of the reverse brake B1 and the direct coupling clutch C1, and pressure control of the oil chamber 23 of the secondary pulley 21. DS1 is an upshift solenoid valve that generates an upshift signal pressure Pds1, and DS2 is a downshift solenoid valve that generates a downshift signal pressure Pds2. The solenoid valves DS1 and DS2 have not only shift control but also functions of closing control and quick filling of the primary oil chamber 13 during idle stop described later. 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.

Solenoid valves DS1 and DS2 are controlled as follows according to the running state.

In Table 1, ○ indicates an operating state, and × indicates a non-operating state. In addition, (circle) and x contain not only an ON state or an OFF state but a duty control state. The closing control in which both solenoid valves are simultaneously turned OFF is the closing control when the vehicle is stopped and the vehicle is stopped when the vehicle is stopped, and is executed to prevent the belt from slipping when the vehicle restarts. Even when the gear ratio is not returned to the lowest level and the vehicle speed is very low (2 to 4 km / h) or less, both solenoid valves may be turned off to perform the closing control. . On the other hand, the closing control for turning on both solenoid valves is performed during the garage shift.

In FIG. 3, 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, but the hydraulic circuit such as the lockup clutch 3a built in the torque converter 3 is the same as that of the present invention. Omitted because there is no direct relationship.

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 clamping pressure control valve 79.

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. 3 is a transient state, and the left side is a 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.

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.

The upshift ratio control valve 76 and the downshift ratio control valve 77 change the valve opening area according to the relative relationship between the upshift signal pressure Pds1 and the downshift signal pressure Pds2, and return to the oil chamber 13 of the primary pulley 11. This is a flow control valve that adjusts the amount of hydraulic oil. That is, as shown in FIG. 4, the upshift ratio control valve 76 includes a spool 76b biased in one direction by a spring 76a, and a signal pressure Pds2 is applied to a signal port 76c on one end side where the spring 76a is accommodated. Is entered. The signal pressure Pds1 is input to the signal port 76d on the other end side facing the spring load. Line pressure P _L is supplied to the intermediate input port 76 e, and the output port 76 f is connected to the oil chamber 13 of the primary pulley 11. A port 76h connected to a port 78h of a ratio check valve 78 described later is formed between the input port 76e and the drain port 76g, and a downshift ratio control is provided between the output port 76f and the signal port 76d. A port 76 i connected to the port 77 f of the valve 77 and the port 78 d of the ratio check valve 78 is formed.

The downshift ratio control valve 77 includes a spool 77b biased in one direction by a spring 77a, and a signal pressure Pds1 is input to a signal port 77c on one end side in which the spring 77a is accommodated. The signal pressure Pds2 is inputted to the signal port 77d on the other end side facing the spring load. In the intermediate portion, a drain port 77e, a port 77f connected to the port 76i of the upshift ratio control valve 76, and a port 77g connected to the port 78f of the ratio check valve 78 are formed in this order.

The ratio check valve 78 switches the hydraulic pressure of the oil chamber 13 of the primary pulley 11 from flow control to pressure control during the closing control, and maintains the primary pressure at a predetermined pressure corresponding to the ratio with the secondary pressure. It is a pressure control valve. The ratio check valve 78 includes a spool 78b biased in one direction by a spring 78a, and the hydraulic pressure of the secondary pulley oil chamber 23 is input to a signal port 78c on one end side where the spring 78a is accommodated. The oil pressure of the primary oil chamber 13 is input to the signal port 78d on the other end side facing the spring load via the ports 76f and 76i of the upshift ratio control valve 76. Note that the pressure receiving area of the signal port 78d to which the primary pressure is input is larger by α times than the pressure receiving area of the signal port 78c to which the secondary pressure is input. Line pressure P _L is supplied to the input port 78e, and the output port 78f is connected to the port 77g of the downshift ratio control valve 77. Further, a port 78h connected to the port 76h of the upshift ratio control valve 76 is formed between the output port 78f and the drain port 78g.

During the closing control, both solenoid valves DS1 and DS2 are turned OFF or ON, so that the upshift ratio control valve 76 is in the right position in FIG. 4 and the downshift ratio control valve 77 is in the left position in FIG. When the sum of the load due to the secondary pressure and the spring load is relatively larger than α times the load due to the primary pressure, the ratio check valve 78 is in the left position in FIG. 4 and is connected to the input port 78e of the ratio check valve 78. The supplied line pressure P _L is supplied from the output port 78f to the primary oil chamber 13 through the ports 77g and 77f of the downshift ratio control valve 77 and the ports 76i and 76f of the upshift ratio control valve 76. Conversely, when the α times the load due to the primary pressure is relatively larger than the sum of the load due to the secondary pressure and the spring load, the ratio check valve 78 is switched to the right position in FIG. Therefore, the primary pressure is drained from the output port 78f and the port 78h via the ports 76h and 76g of the upshift ratio control valve 76. Actually, the spool 78b of the ratio check valve 78 is balanced at an intermediate position between a position connecting the output port 78f and the input port 78e and a position connecting the output port 78f and the port 78h. Thus, the ratio check valve 78 can control the primary pressure so that the ratio between the primary pressure and the secondary pressure has a predetermined relationship, and can maintain the predetermined gear ratio. The supply oil passage connecting the ratio check valve 78 and the primary oil chamber 13 passes through the upshift ratio control valve 76 and the downshift ratio control valve 77, and has a small diameter in the oil passage between the ports 78f and 77g. A simple orifice 90 is set. Due to the action of these orifices 90, a sudden speed change is prevented when switching to the closing control.

The clamping pressure control valve 79 is a valve for controlling the hydraulic pressure (secondary pressure) of the hydraulic oil chamber 23 of the secondary pulley 21. A spool 79g biased in one direction by a spring 79f is provided, and a constant pressure Psm is supplied from a solenoid modulator valve 73 to a signal port 79a on one end side 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 secondary pressure is fed back to the port 79d. The solenoid pressure Psls is supplied to the signal port 79e on the other end side in which the spring 79f is accommodated. Port 79h is a drain port. 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 of the secondary pulley 21 as a secondary pressure. The hydraulic pressure (secondary pressure) in the hydraulic oil chamber 23 is detected by the hydraulic pressure sensor 108, and the belt clamping pressure or the belt transmission torque can be obtained based on the detected hydraulic pressure.

FIG. 5 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 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 line pressure P _L. As shown in FIG. 5, although both the clutch control pressure and the secondary pressure are controlled by the solenoid pressure Psls, the secondary pressure is always set to exceed the clutch control pressure.

Next, a method for controlling the continuously variable transmission according to the present invention will be described with reference to FIG. FIG. 6 shows an example of control when the vehicle stops from the deceleration state and the engine automatically stops after the idling stop determination. The vehicle speed, the ratio (pulley ratio), the engine speed, the shift control solenoid valve DS1, Each time change of operation of DS2 and primary oil pressure is shown. In the primary hydraulic pressure, the solid line represents the hydraulic pressure change of the present invention, and the broken line represents the conventional hydraulic pressure change (see FIG. 7).

In FIG. 6, t1 is the time when the pulley ratio reaches the lowest level, t2 is the start of the closing control, t3 is the idle stop execution determination, t4 is the engine stop, and t5 is the engine restart. Is the same as FIG. When the vehicle is stopped from the deceleration state, it is necessary to return the pulley ratio of the continuously variable transmission to the lowest state before the vehicle stops. Therefore, the solenoid valve DS1 is turned OFF, the solenoid valve DS2 is turned ON, and the ports 76f, 76i, 77f , 77e, the hydraulic oil is drained from the primary oil chamber 13, and the hydraulic oil is continuously drained even after reaching the lowest state. When reaching the lowest level, the movable sheave 11b of the primary pulley 11 comes into contact with the stopper 12a, so that the volume of the pulley oil chamber 13 does not change, and thereafter, the air corresponding to the volume of the hydraulic oil discharged from the pulley oil chamber 13 is lost. Flows into the pulley oil chamber 13. Specifically, since the hydraulic oil is discharged through the ratio control valves 76 and 77 due to the oil level difference (head H) between the shaft hole 10a and the oil pan even after returning to the lowest level, the transmission case Air flows from the connecting portion between the 40 oil passages 41 and the axial hole 10a of the primary shaft 10 (see FIG. 2).

At time t2, the solenoid valves DS1 and DS2 are both turned OFF for closing control, and the primary oil chamber 13 is supplied with hydraulic pressure from the ratio check valve 78. However, the hydraulic oil is not supplied due to the orifice 90 in the supply oil passage. Filling is delayed and air is not discharged. Therefore, in the present invention, simultaneously with the idle stop execution determination t3, the charging-side solenoid valve DS1 is turned on for a short time, and the upshift ratio control valve 76 is switched to the left position in FIG. Therefore, the line pressure is directly supplied to the primary oil chamber 13 via the ports 76e and 76f. Since this supply oil passage has no orifice, the primary oil chamber 13 is filled with hydraulic oil in a short time, and the air in the oil chamber 13 is discharged. In this example, the ON time of the solenoid valve DS1 is shorter than the period (t3 to t4) from the idle stop execution determination to the engine stop, but the same period may be used, or the ON state may be maintained after the engine stop ( However, since the oil pump discharge pressure disappears when the engine is stopped, rapid filling is not performed. The ON start timing of the solenoid valve DS1 does not need to be the same as the idle stop execution determination t3, but it needs to be at least before the engine is automatically stopped t4.

When the engine is restarted at time t5, the air in the primary oil chamber 13 has already been discharged, so the oil pressure in the primary oil chamber 13 rises quickly, eliminating the delay in boosting the belt clamping pressure, and thus causing belt slippage. Can be prevented. In addition, since the engine driving force can be transmitted promptly at the time of idling stop return, the starting performance at the time of restart is improved.

For example, when the period (t1 to t2) from reaching the lowest level to the start of the closing control is long, such as when the non-noro operation is continued at a low speed, air easily flows into the primary oil chamber, Deterioration of starting performance becomes a problem. By using the control of the present invention, such a problem can be solved, and the operation method of the solenoid valve can be changed (the control software is changed) without changing the existing device (including the hydraulic circuit). It can be realized at low cost.

In the above embodiment, two ratio control valves 76 and 77 for upshifting and downshifting are provided as ratio control valves, and upshift solenoid valve DS1 and downshift solenoid valve DS2 are provided for both control valves. The flow rate of the hydraulic oil in the primary oil chamber was controlled by inputting the signal pressure in opposition to each other, but the ratio control valve was composed of a single valve, and the upshift solenoid valve DS1 and the downshift valve were provided at both ends of the ratio control valve. The flow rate of the hydraulic oil in the primary oil chamber may be controlled by inputting the signal pressure of the solenoid valve DS2 oppositely. Further, the output pressure of the ratio check valve 78 is supplied to the primary oil chamber 13 via the two ratio control valves 76 and 77. However, the present invention is not limited to this, and it is supplied via another oil passage. May be. In this case, it is necessary to set an orifice in this separate oil passage.

1 Engine 2 Continuously Variable Transmission 4 Transmission 6 Oil Pump 7 Hydraulic Control Device 11 Primary Pulley 13 Primary Oil Chamber 21 Secondary Pulley 23 Secondary Oil Chamber 76 Upshift Ratio Control Valve 77 Downshift Ratio Control Valve 78 Ratio Check Valve 79 Nipping control valve 90 Orifice 100 Electronic control device 101 Engine speed sensor 102 Vehicle speed sensor (secondary pulley speed sensor)
103 Throttle opening sensor 104 Shift position sensor 105 Primary pulley rotation speed sensor 106 Brake sensor 108 Hydraulic sensor B1 Reverse brake (start clutch)
C1 Direct clutch SLS Linear solenoid valve DS1 Upshift solenoid valve DS2 Downshift solenoid valve

Claims (2)

Engine,
Idle stop control means for performing an idle stop execution determination when a predetermined stop condition is satisfied, and then automatically stopping the engine,
An oil pump driven by the engine;
A belt type continuously variable transmission having a primary pulley and a secondary pulley for transmitting engine power to drive wheels;
A hydraulic control device for controlling the hydraulic pressure supplied to the primary pulley and the secondary pulley of the continuously variable transmission based on the hydraulic pressure generated by the oil pump;
Engine speed detecting means for detecting the engine speed;
Vehicle speed detection means for detecting the vehicle speed;
In an idle stop vehicle comprising pulley ratio detection means for detecting a pulley ratio of the continuously variable transmission,
The hydraulic control device includes:
Complete the control to make the pulley ratio the maximum gear ratio before stopping the vehicle, continue the control to discharge the hydraulic oil of the primary pulley even after reaching the maximum gear ratio,
A continuously variable transmission for an idle stop vehicle characterized in that when the idle stop control means makes an idle stop execution determination after the vehicle stops, the primary pulley is rapidly filled with hydraulic oil for a predetermined time immediately before the engine automatic stop. Control device. The hydraulic control device includes:
A ratio control valve for controlling the flow rate of hydraulic oil to the primary pulley;
A solenoid valve for generating a signal pressure for operating the ratio control valve;
A ratio check valve that receives the hydraulic pressure of the secondary pulley as a signal pressure, and controls the hydraulic oil pressure to the primary pulley;
An orifice provided in an oil passage connecting the ratio check valve and the primary pulley,
In order to set the pulley ratio to the maximum gear ratio before stopping the vehicle, the hydraulic oil of the primary pulley is discharged by the ratio control valve,
At the time of stopping the vehicle or just before that, the hydraulic oil pressure to the primary pulley is pressure controlled by the ratio check valve instead of the ratio control valve to maintain the maximum gear ratio state,
After the vehicle stops, when the idle stop control means makes an idle stop execution determination, the primary pulley is rapidly filled with hydraulic oil by the ratio control valve instead of the ratio check valve for a predetermined time immediately before the engine automatic stop. The control device for a continuously variable transmission for an idle stop vehicle according to claim 1,

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