JP2012072844A - Hydraulic control device of belt type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic transmission of a belt type continuously variable transmission, which includes a line pressure control valve, a start clutch pressure switching valve, a shift control valve, and a belt narrow pressure control valve, and controls these valves by a plurality of solenoid valves.SOLUTION: A fail safe switching valve is disposed in an oil path between a linear solenoid valve and a line pressure control valve. On condition that signal pressure from the linear solenoid valve exceeds a prescribed pressure by the switch valve to which the signal pressure from the linear solenoid valve and fixed pressure obtained by reducing light pressure, output pressure to the line pressure control valve is switched to the fixed pressure. When the linear solenoid valve or all the solenoid valves fail, a transmission ratio is set to 1.0 or a desired value.

Description

The present invention relates to a hydraulic control device for a belt-type continuously variable transmission that enables a rim home while ensuring durability of the belt even if a part or all of a solenoid valve fails.

In a belt-type continuously variable transmission, a belt is wound between a primary pulley and a secondary pulley, and the supply oil amount / hydraulic pressure of the oil chambers provided in both pulleys is controlled to control the shift control and the belt clamping pressure control. Is known to do. When controlling this belt type continuously variable transmission, the ratio of the hydraulic oil to the primary oil chamber is controlled by a ratio control valve (flow rate control valve), thereby controlling the pulley ratio and the hydraulic pressure supplied to the secondary oil chamber. The belt clamping pressure is controlled by controlling the clamping pressure control valve (pressure control valve). Of these, the ratio control valve is opposed to the signal pressure from the upshift solenoid valve and the downshift solenoid valve, and controls the amount of oil to the primary oil chamber based on the magnitude relationship between the signal pressures. is doing. On the other hand, a signal pressure is input from the linear solenoid valve to the clamping pressure control valve, and the hydraulic pressure of the secondary oil chamber is controlled in proportion to the signal pressure.

In such a belt type continuously variable transmission hydraulic circuit, when the linear solenoid valve fails due to a failure, etc., or the solenoid wires for all the solenoid valves are disconnected, etc., making it impossible to supply power. In this case, the belt clamping pressure increases. Even in such a situation, it is necessary to avoid cutting the belt and secure a limp home. On the other hand, in recent years, there has been a great demand for low fuel consumption and reduced manufacturing costs, and there is a need to replace belts that satisfy them. Such belts tend to be less durable and have the problem of conflicting with the need to secure the limp home.

As a countermeasure when a solenoid valve has failed in a hydraulic circuit of a belt-type continuously variable transmission conventionally, for example, in Japanese Patent Application Laid-Open No. 11-182666, when a linear solenoid valve for controlling a pilot pressure of a belt clamping pressure control valve has failed, A hydraulic control device is provided that switches to this and switches to the starting clutch pressure of the starting clutch pressure control valve. However, in this hydraulic control device, the starting clutch pressure is controlled by a solenoid valve different from the belt clamping pressure, and in the hydraulic control device in which the starting clutch pressure and the belt clamping pressure are controlled by one linear solenoid valve, the starting clutch pressure is linear. There is no control valve to switch from the solenoid valve, and it cannot be adopted in the first place.

Japanese Patent Laid-Open No. 2001-330135 limits the engine torque when the belt clamping pressure malfunctions to the high pressure side, or changes the gear ratio to 1.0 or less than 1.0 depending on the vehicle speed. There is also a hydraulic control device that reduces the load on the belt by shifting. However, this hydraulic control device does not directly reduce the belt clamping pressure.

JP 11-182666 A JP 2001-330135 A

The present invention was created in view of the above circumstances, and in the case of a hydraulic configuration in which a starting solenoid pressure control, a belt clamping pressure control, and a line pressure control are combined with a single solenoid valve (linear solenoid solenoid valve). A belt that can prevent excessive belt pressure by preventing excessive line pressure and optimizing the gear ratio even if the solenoid valve that is also used and all other solenoids fail An object of the present invention is to provide a hydraulic control device for a continuously variable transmission.

In order to achieve the above object, in the first aspect of the present invention, at least a line pressure control valve (for example, the regulator valve 71 in the embodiment) that regulates the hydraulic pressure supplied from the oil pump to a predetermined pressure and the supply pressure to the starting clutch are controlled. A starting clutch pressure switching valve (for example, the garage shift valve 74 in the embodiment) and a shift control valve for controlling the shift by controlling the amount of hydraulic oil to one of the primary pulley or the secondary pulley (for example, for upshifting in the embodiment) A ratio control valve 76, a downshift ratio control valve 77), and a belt clamping pressure control valve that controls the clamping pressure on the belt wound around both pulleys by controlling the hydraulic pressure applied to the other of the primary pulley or the secondary pulley. For example, a clamping pressure control valve 79) in the embodiment is provided, and these valves are constituted by a plurality of solenoid valves. Gosuru to provide a hydraulic control device for a belt type continuously variable transmission.

The hydraulic control apparatus includes a valve (for example, the clutch modulator valve 72 in the embodiment) that reduces the line pressure to a constant pressure and outputs it, and one solenoid of the plurality of solenoid valves (for example, the linear solenoid SLS in the embodiment). The constant pressure is input, and all of the signal pressure to the line pressure control valve, the signal pressure to the starting clutch pressure, and the signal pressure to the belt clamping pressure control valve are output, and the belt The clamping pressure control valve outputs the supply pressure from the oil pump as the clamping pressure to the belt by the input of the signal pressure by the one solenoid, and when all the power supply to the plurality of solenoid valves is shut off The output pressure of the one solenoid valve maintains an open state, and the output pressure of the solenoid valve that controls the shift control valve maintains a closed state. In addition, a fail-safe switching valve (for example, the fail-safe valve 80 in the embodiment) is provided in the oil passage between the one solenoid valve and the line pressure control valve, and the switching valve is the one solenoid valve. The line pressure control valve is supplied on the condition that the signal pressure to the line pressure control valve and the constant pressure are input and the signal pressure from the one solenoid valve to the line pressure control valve exceeds the constant pressure. The output pressure is switched to the constant pressure, and the line pressure regulated by the line pressure control valve decreases. In addition, limp home is enabled by providing a gear ratio control means for shifting the gear ratio to 1.0 although the output pressure of the solenoid valve for controlling the gear shift control valve is closed.

The hydraulic control device for the belt type continuously variable transmission according to the first aspect of the present invention has one solenoid valve (for example, in the present embodiment, the linear solenoid valve SLS has a signal pressure to the line pressure control valve, a starting clutch pressure, This is a hydraulic configuration that outputs a signal pressure to the belt clamping pressure control valve. In this hydraulic configuration, it is assumed that all solenoid valves including the linear solenoid valve are unable to supply power due to solenoid wire disconnection or the like. The “all solenoids” referred to here include, for example, the solenoid valves DS1 and DS2 for shift control in the embodiment, the on / off solenoid 81 for failsafe valve control, or the solenoid for lockup control not described in this specification. Includes valves.

In this case, even if the signal pressure from the linear solenoid becomes excessive, the pressure can be reduced by switching to a constant pressure with the fail-safe valve, and the operating hydraulic pressure of one of the primary pulley or the secondary pulley (for example, the secondary pulley in this embodiment) The belt clamping pressure can be reduced. As for the transmission gear ratio, both the transmission control valves are turned off and the closing control is executed. By shifting to the specified transmission gear ratio 1.0, the other of the primary pulley or the secondary pulley (for example, the primary pulley in this embodiment) The working hydraulic pressure, and hence the belt clamping pressure, can be reduced.

Also in the second aspect of the present invention, at least a line pressure control valve that regulates the hydraulic pressure supplied from the oil pump to a predetermined pressure, a starting clutch pressure switching valve that controls the supply pressure to the starting clutch, and a primary pulley or a secondary pulley. A shift control valve that controls the shift by controlling the amount of hydraulic oil to one side, and a belt that controls the clamping pressure on the belt wound around both pulleys by controlling the hydraulic pressure to the other of the primary pulley or the secondary pulley Provided is a hydraulic control device for a belt-type continuously variable transmission that includes a clamping pressure control valve and controls these valves with a plurality of solenoid valves.

The hydraulic control device includes a valve for reducing the line pressure to a constant pressure and outputting the pressure, and one solenoid of the plurality of solenoid valves inputs the constant pressure, and a signal pressure to the line pressure control valve The start clutch pressure and the signal pressure to the belt clamping pressure control valve are all output, and the belt clamping pressure control valve supplies the pressure supplied from the oil pump by the input of the signal pressure by the one solenoid. Is further provided as failing means for determining whether or not the one solenoid valve has failed to the high pressure side, and the fail determining means has determined that the failure has been failed to the high pressure side. The output pressure of the one solenoid valve is kept open. Further, a fail-safe switching valve is provided in an oil passage between the one solenoid valve and the line pressure control valve, and the switching valve is configured to transmit a signal pressure from the one solenoid valve to the line pressure control valve. And the constant pressure are input, and the output pressure to the line pressure control valve is switched to the constant pressure when the fail determination means determines that the high pressure side has failed. The line pressure is reduced. On the other hand, it can be controlled so as to obtain a desired gear ratio by a solenoid valve that controls the gear shift control valve.

As in the first aspect of the present invention, the hydraulic control device for the belt type continuously variable transmission according to the second aspect of the present invention includes a single linear solenoid valve having a signal pressure to the line pressure control valve, a starting clutch pressure, and a belt clamping pressure. This is a hydraulic configuration that outputs a signal pressure to the control valve. In this hydraulic configuration, it is assumed that the linear solenoid fails to the high pressure side. A fail-safe switching valve is provided between the linear solenoid valve and the line pressure control valve. When it is determined that a failure has occurred, the output pressure to the line pressure control valve is switched to a constant pressure. However, since the solenoid valve for the speed change control valve is normal, it can be controlled so as to achieve a desired speed change ratio. Therefore, both the primary pulley and the secondary pulley can be controlled to rapidly increase the operating hydraulic pressure, and can be controlled to a desired gear ratio.

According to the first aspect of the present invention, the line pressure control valve can be depressurized and the gear ratio can be shifted to 1.0 even when power supply to all the solenoid valves becomes impossible. Further, according to the second aspect of the present invention, even when the linear solenoid valve responsible for line pressure control, belt clamping pressure control, and starting clutch pressure control fails to the high pressure side, the line pressure control valve can be reduced, The gear ratio can be set to a desired ratio. Therefore, an increase in the belt clamping pressure can be regulated, and belt durability can be ensured and limp home can be provided at the time of failure.

It is a skeleton figure of the belt type continuously variable transmission concerning one embodiment of the present invention. FIG. 2 is a hydraulic circuit diagram of the belt type continuously variable transmission shown in FIG. 1. FIG. 10 is a hydraulic circuit diagram of a part of the hydraulic circuit shown in FIGS. 2, 5, and 9. It is a figure which shows each characteristic of a line pressure, a clutch modulator pressure, a clutch control pressure, and a secondary pressure with respect to solenoid pressure Psls of the belt-type continuously variable transmission shown in FIG. It is a hydraulic circuit diagram of the belt type continuously variable transmission of the present invention. 6 is a flowchart of hydraulic pressure controlled in the first embodiment of the present invention in the hydraulic circuit of FIG. 5. 6 is a flowchart of hydraulic pressure controlled in the second embodiment of the present invention in the hydraulic circuit of FIG. 5. It is a figure which shows each characteristic of a line pressure, a clutch modulator pressure, a clutch control pressure, and a secondary pressure with respect to solenoid pressure Psls of the belt-type continuously variable transmission shown in FIG. It is an improved view of the hydraulic circuit diagram of the belt type continuously variable transmission of the present invention.

Next, a control device for a belt type continuously variable transmission according to an embodiment of the present invention will be described in detail with reference to the drawings. Prior to the description of the control device for the belt type continuously variable transmission, the outline of the configuration of the vehicle equipped with the belt type continuously variable transmission, the hydraulic circuit employed in the vehicle, the basic operation of the vehicle, and the like will be described.

≪About vehicle configuration≫
FIG. 1 shows an example of the configuration of a vehicle according to the present invention. The engine output shaft 1 a 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 (CVT), a hydraulic control device 7, an oil pump 6 driven by an engine, and the like.

The oil pump 6 is driven by a pump impeller 3 a of the torque converter 3. The turbine runner 3b of the torque converter 3 is connected to a turbine shaft (input shaft) 5, and the stator 3c is supported by a case via a one-way clutch 3d. A lock-up crunch 3e is provided between the turbine shaft 5 and the pump impeller 3a.

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 coupling clutch C1. The reverse brake B1 functions as a starting clutch when moving forward, and the direct coupling clutch C1 functions as a starting clutch when moving backward. 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 vehicle travels forward. Conversely, when the reverse brake B1 is released and the direct clutch C1 is engaged, the vehicle travels backward.

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. Shift control is performed by controlling the flow rate of the hydraulic oil supplied to the oil chamber 13 with ratio control valves 76 and 77 described later.

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. 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 device 100 includes an ignition switch IG, an engine speed sensor 101, a vehicle speed sensor 102 (or a secondary pulley speed sensor), a throttle opening sensor 103 (or an accelerator opening sensor), a shift position sensor 104, and a primary pulley rotation. Detection signals are input from the number sensor 105, the brake sensor 106, the CVT oil temperature sensor 107, and the hydraulic pressure sensor 108 that detects the secondary pressure. Of course, other signals may be input as the input signal. The primary pulley rotational speed sensor 105 can detect the rotational speed after the starting clutch (for example, B1). The pulley ratio can be calculated from the detection signals of the primary pulley rotation speed sensor 105 and the vehicle speed sensor 102. In the present embodiment, in order to simplify the description, an example in which both the engine 1 and the continuously variable transmission 2 are controlled by the single electronic control device 100 has been shown. Both electronic control units are linked to each other via a communication bus.

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 pipes. The electronic control unit 100 determines the target pulley ratio or the primary rotation speed according to a preset shift map according to the vehicle speed and the throttle opening, and controls the solenoid valves DS1 and DS2 in the hydraulic control unit 7 to The amount of oil supplied to the primary oil chamber 13 of the continuously variable transmission 2 is adjusted, and the pulley ratio or the primary rotational speed is feedback controlled to the target value.

Further, the electronic control unit 100 obtains the belt transmission torque from the engine torque and the gear ratio, and controls the solenoid valve SLS in the hydraulic control unit 7 so as to obtain the minimum belt clamping pressure that does not cause belt slip. Thus, the feed oil pressure (secondary pressure) to the secondary oil chamber 23 is feedback controlled to the target value. At this time, the actual secondary pressure is detected by the hydraulic pressure sensor 108. Further, the solenoid valve SLS in the hydraulic control device 7 has a function of controlling the hydraulic pressure (transient pressure) supplied to the reverse brake B1 and the direct coupling clutch C1.

≪About hydraulic circuit≫
FIG. 2 shows an example of a conventional hydraulic circuit provided in the hydraulic control device 7, and FIG. 3 is an enlarged view of a part thereof. 2 and 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, and 77 is a downshift ratio. A 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 line pressure regulation control, transient control of the reverse brake B1 and direct coupling clutch C1, and pressure regulation of the oil chamber 23 of the secondary pulley 21, DS1 is An upshift solenoid valve that regulates and controls the upshift signal pressure Pds1, and DS2 is a downshift solenoid valve that regulates and controls the downshift signal pressure Pds2. In this embodiment, the solenoid valve SLS is a normally open (N / O type) linear solenoid valve, and the solenoid valves DS1 and DS2 are both normally closed (N / C type) duty solenoid valves. The oil pressure source of the oil pressure control device 7 is only the oil pump 6 driven by the engine 1, but a special oil pump such as an eco-run electric pump not shown in FIG. 2 may be provided.

The regulator valve 71 is a valve that regulates the discharge pressure of the oil pump 6 to a predetermined line pressure PL, and the linear solenoid valve SLS is input to the signal port 71a. Therefore, the line pressure is adjusted to a hydraulic pressure proportional to the solenoid pressure Psls. The clutch modulator valve 72 is a valve that outputs a clutch modulator pressure Pcm that is a source pressure of a supply pressure to the direct coupling clutch C1 and the reverse brake B1. The solenoid modulator valve 73 is a valve that regulates the clutch modulator pressure Pcm to generate a constant solenoid modulator pressure Psm.

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. The garage shift valve 74 uses the output pressure Psls from the linear solenoid valve SLS as a starting clutch pressure only at the time of starting. However, after the engagement of the clutch is completed, the line pressure is reduced to a constant pressure Pcm and the clutch is engaged. It has a function to maintain. In FIG. 2, the left side from the center line of the garage shift valve 74 shows a transient state, and the right side shows a holding state. The garage shift valve 74 includes a spool 74b urged in one direction by a spring 74a. Signal ports 74c and 74d are formed in the same direction as the spring load, and the upshift signal pressure Pds1 and the downshift. The signal pressure Pds2 for use is input. A solenoid modulator pressure Psm is input to the counter port 74h in a direction opposite to the spring load. The solenoid pressure Psls is input from the linear solenoid valve SLS to the port 74e.

Since the solenoid valves DS1 and DS2 are both turned on during the garage shift, the signal pressures Pds1 and Pds2 input to the signal ports 74c and 74d are both turned on. The spool 74b moves downward against the spring 74a. As a result, the modulator valve 74 enters a transient state shown on the left side of the center line in FIG. Therefore, the solenoid 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. For this reason, gentle engagement can be started 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 spool 74b is moved upward by the solenoid modulator pressure Psm, and the modulator valve 74 is in the holding state shown on the right side of the center line in FIG. Therefore, the clutch modulator pressure Pcm input to the port 74g 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. That is, when at least one of the signal pressures Pds1 and Pds2 is turned off, the engagement state of the direct coupling 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 that is 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. It selectively leads to C1 or 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. The manual valve 75 supplies hydraulic pressure to the direct clutch C1 and drains the reverse brake B1 in the R range, and supplies hydraulic pressure to the reverse brake B1 and drains the direct clutch Cl in the D, S, and B ranges. . 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. That is, as shown in FIG. 3, 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 facing the spring load. A line pressure PL 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 Pdsl is input to a signal port 77c on one end side in which the spring 77a is accommodated. The signal pressure Pds2 is input to the signal port 77d at the other end 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 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 a preset relationship. It is a valve for holding. 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 in which the spring 78a is accommodated. The oil pressure of the primary pulley 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. A line pressure PL is supplied to the input port 78e, and an output port 78h is connected to a port 77g of the goun shift 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.

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 79e urged 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 at one end facing the spring load. Line pressure PL 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. For this reason, 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.

As a calculation method of the belt clamping pressure or the belt transmission torque, for example, the secondary hydraulic pressure is detected by the hydraulic sensor 108, the belt clamping pressure is calculated from the secondary hydraulic pressure and the pressure receiving area, and the belt clamping pressure and the friction between the belt and the pulley are calculated. The belt transmission torque can be calculated from the coefficient, the belt winding diameter, and the like.

The characteristics of the line pressure PL, the clutch modulator pressure Pcm, the clutch control pressure, and the secondary pressure with respect to the solenoid pressure Psls are as shown in FIG. Specifically, the line pressure PL is adjusted to a hydraulic pressure that is substantially proportional to the solenoid pressure Psls. The clutch modulator pressure Pcm is the same as the line pressure PL until the solenoid pressure Psls reaches a predetermined value, and when it exceeds the predetermined value, the clutch modulator pressure Pcm is controlled to a constant pressure. 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 PL. As shown in FIG. 4, the line pressure, the clutch control pressure, and the secondary pressure are all controlled by the linear solenoid valve SLS, but the secondary pressure is always set to exceed the clutch control pressure. The secondary pressure is detected by the hydraulic pressure sensor 108.

<< Hydraulic Circuit in the Present Invention >>
FIG. 5 illustrates a hydraulic circuit of the belt type continuously variable transmission according to the present invention, which is an improvement of the hydraulic circuit of the hydraulic control device 7 shown in FIG. Therefore, in FIG. 5, the same reference numerals as those in FIGS. 1 and 2 are the same, and FIG. 3 is also referred to as a part of FIG. 5 (the same applies to the hydraulic circuit of FIG. 9 described later). ). In the hydraulic circuit of FIG. 5, a fail safe valve 80 is added to the oil passage between the linear solenoid SLS and the regulator valve 71. As described above, the regulator valve 71 is a valve that regulates the line pressure PL, but the signal pressure Psls from the linear solenoid valve SLS is input to the failsafe valve 80 due to the addition of the failsafe valve 80. When the fail safe valve 80 does not operate, the solenoid port pressure Psls is input to the port 71a of the regulator valve 71 as in FIG. 2, and the line pressure is adjusted to a hydraulic pressure proportional to the solenoid pressure Psls. Then, the regulated line pressure PL is reduced by the clutch modulator valve 72 to output a constant clutch modulator pressure Pcm. Thereafter, the clutch modulator pressure Pcm is regulated by the solenoid modulator valve 73 to generate a constant solenoid modulator pressure Psm. The modulator pressure Psm is input not only to the downshift solenoid valve DS2 and the upshift solenoid valve DS1, but also to the failsafe valve 80, as in FIG.

The fail-safe valve 80 outputs the solenoid pressure Psls when the input solenoid pressure 80 is equal to or lower than a predetermined pressure, but switches the output pressure to the modulator pressure Psm when the pressure exceeds the predetermined pressure. Therefore, when the linear solenoid valve SLS, the solenoid modulator valve 73, etc. are normal, the solenoid pressure Psls is within an appropriate range, so the failsafe valve 80 does not operate, and the solenoid pressure Psls is not connected to the port of the regulator valve 71. It is input to 71a.

In the first embodiment of the present invention, the power supply to not only the linear solenoid valve SLS but also the other solenoid valves 73, DS1, and DS2 is disabled because the solenoid wires that supply power to all the solenoid valves are disconnected. In this case, the solenoid modulator valve 73 is also disabled, and the linear solenoid valve Psls is an N / O type, so that the Psls is fully open. At this time, the clutch modulator pressure Pcm limited to a constant pressure is output as the modulator pressure Psm. When the solenoid pressure Psls input to the fail safe valve 80 exceeds the modulator pressure Psm, the output pressure is switched to Psm and output. As a result, when the solenoid pressure Psls becomes excessive, the line pressure PL control can be properly executed by the regulator valve 71 even if the solenoid modulator valve 73 does not operate, and the belt pressure control valve 79 is controlled to control the belt. The clamping pressure can be reduced.

Here, since the solenoid valves DS1 and DS2 are N / C types, they are turned off when power supply is not possible. Therefore, so-called confinement control is performed in which the supply of hydraulic oil to the primary pulley can be switched from flow control to pressure control. At this time, the upshift ratio control valve 76 is in the right position in FIG. 3, 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. 3 and is connected to the input port 78e of the ratio check valve 78. The supplied line pressure PL 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. In this manner, 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 (here, 1.0). Therefore, since the shift to the small speed ratio 1.0 is performed, the belt clamping pressure is reduced in combination with the above-described reduction of the line pressure PL to the clamping pressure control valve 79.

FIG. 6 shows an explanatory diagram when power supply to all the solenoid valves described above is disabled. When all the power supply to the solenoid valve is shut off (S1), the linear solenoid valve SLS is N / O type, so the output solenoid pressure Psls is maximum (S2), and the failsafe valve 80 has the solenoid pressure Psls at a predetermined pressure. If it exceeds, the output pressure is switched to Psm (S3). As a result, the input signal pressure to the regulator valve 71 decreases to Psm, so that the line pressure PL decreases (S4), and the belt clamping pressure decreases via the clamping pressure control valve 70 (S5). When power supply to all the solenoid valves becomes impossible, the output of the upshift solenoid valve DS1 and the downshift solenoid valve DS2 responsible for gear ratio control also become zero (S6). Is executed (S7), and the gear ratio is shifted to 1.0 (S8).

Next, as a second embodiment of the present invention, it is assumed that the linear solenoid valve SLS has failed to the high pressure side due to disconnection of the solenoid wire, contamination with foreign matter, or the like. Whether or not the linear solenoid valve SLS has failed to the high pressure side is determined by a fail determination unit. For example, the determination is made by detecting the actual secondary pressure using the hydraulic pressure sensor 108 (see FIG. 1) shown in FIG. In the fail-safe valve 80, both the solenoid pressure Psls and the modulator pressure Psm are input to the fail-safe valve 80. At this time, when the solenoid pressure Psls input to the failsafe valve 80 exceeds a predetermined pressure, the output pressure is switched to Psm and output. As a result, the linear solenoid valve SLS and the solenoid pressure Psls can be regulated so as not to be higher than the desired modulator pressure Psm. The regulator valve 71 appropriately executes the line pressure PL control and controls the pinching control valve 79. The belt clamping pressure can be reduced.

In the above case, solenoid valves other than the linear solenoid valve SLS are normal, and especially the upshift solenoid DS1 and the downshift solenoid DS2 are also normal, so the flow rate control to the hydraulic oil chamber of the primary pulley is also free, and the gear ratio is It can be controlled to a desired ratio.

Referring to FIG. 7, there is shown an explanatory diagram when power supply to the linear solenoid valve SLS described above becomes impossible. When the linear solenoid valve SLS becomes unable to supply power (S10), the output solenoid pressure Psls becomes maximum (S11) because the linear solenoid valve SLS is the N / O type as in the explanatory diagram on the right side of FIG. When the solenoid pressure Psls exceeds a predetermined pressure, the output pressure of the valve 80 is switched to Psm (S12). Then, when the input signal pressure to the regulator valve 71 decreases to Psm, the line pressure PL decreases (S13), and the belt clamping pressure decreases via the clamping pressure control valve 70 (S14). On the other hand, unlike the explanatory diagram on the left side of FIG. 6, in the case of FIG. 7, since the upshift solenoid valve DS1 and the downshift solenoid valve DS2 are supplied with power, the outputs Pds1 and Pds2 having the same output can be controlled. . Accordingly, the gear ratio is maintained at a desired pressure as usual (not shown).

The characteristics of the line pressure PL, the clutch modulator pressure Pcm, the clutch control pressure, and the secondary pressure with respect to the solenoid pressure Psls are as shown in FIG. Specifically, except for the line pressure PL and the secondary pressure, it is the same as in FIG. 4, and the secondary pressure is also adjusted to a hydraulic pressure slightly lower than the hydraulic line pressure PL. However, when the line pressure PL and the secondary pressure reach a predetermined value, the pressure is set to be greatly reduced.

Finally, referring to FIG. 9, as an improved example of the hydraulic circuit of FIG. 5, an N / O type on / off solenoid 81 is provided in the oil path of the modulator pressure Psm from the solenoid module valve 73 to the failsafe valve 80. Yes. Therefore, the fail safe valve 80 can be switched by the input of the on / off signal pressure of the on / off solenoid 81. In this hydraulic circuit, the power supply to all the solenoid valves is shut off in the first embodiment of the present invention. However, the N / O type on / off solenoid 81 has a fail-safe modulator pressure Psm even when power supply is not possible. Since it is inputted to the valve 80, it is the same as the case of FIG. In the second embodiment of the present invention, only the linear solenoid valve SLS is in a failed state, and the on / off solenoid 81 is normal, so that the fail-safe valve 80 can be switched.

Although omitted in FIGS. 2, 5, and 9, when a lock-up control valve exists as a solenoid other than the linear solenoid valve SLS, a solenoid valve for controlling the lock-up control valve is also required. Therefore, the other solenoid valve referred to in this specification includes a so-called lock-up control valve.

The embodiment and concept of the hydraulic control device for a belt-type continuously variable transmission according to the present invention have been described above. However, the present invention is not limited to this, and the spirit described in the claims and the description etc. Those skilled in the art will appreciate that other variations and modifications can be obtained without departing from the teachings and teachings.

11 Primary pulley 13 Oil chamber 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 pressure control valve 80 Fail safe valve 108 Hydraulic sensor

Claims (2)

Controls at least the line pressure control valve that regulates the hydraulic pressure supplied from the oil pump to a predetermined pressure, the starting clutch pressure switching valve that controls the supply pressure to the starting clutch, and the amount of hydraulic oil to one of the primary pulley or the secondary pulley A shift control valve that controls the shift by this, and a belt clamping pressure control valve that controls the clamping pressure on the belt wound around both pulleys by controlling the hydraulic pressure to the other of the primary pulley or the secondary pulley, these A hydraulic control device for a belt-type continuously variable transmission that controls a plurality of solenoid valves with a plurality of solenoid valves,
A valve for reducing the line pressure to a constant pressure and outputting it;
One solenoid of the plurality of solenoid valves inputs the constant pressure and receives all of the signal pressure to the line pressure control valve, the starting clutch pressure, and the signal pressure to the belt clamping pressure control valve. The belt clamping pressure control valve outputs a supply pressure from the oil pump as a clamping pressure to the belt by inputting a signal pressure by the one solenoid;
When all the power supplies to the plurality of solenoid valves are shut off, the output pressure of the one solenoid valve is kept open, and the output pressure of the solenoid valve that controls the shift control valve is kept closed. And
A fail-safe switching valve is provided in an oil passage between the one solenoid valve and the line pressure control valve, and the switching valve is configured to detect the signal pressure from the one solenoid valve to the line pressure control valve and the line pressure control valve. A constant pressure is input, and the output pressure to the line pressure control valve is switched to the constant pressure on condition that the signal pressure from the one solenoid valve to the line pressure control valve exceeds a predetermined pressure,
A hydraulic control device for a belt-type continuously variable transmission, comprising: a gear ratio control means that shifts the gear ratio to 1.0 when the output pressure of a solenoid valve that controls the gear shift control valve is closed; . Controls at least the line pressure control valve that regulates the hydraulic pressure supplied from the oil pump to a predetermined pressure, the starting clutch pressure control valve that controls the supply pressure to the starting clutch, and the amount of hydraulic oil to one of the primary pulley or the secondary pulley A shift control valve that controls the shift by this, and a belt clamping pressure control valve that controls the clamping pressure on the belt wound around both pulleys by controlling the hydraulic pressure to the other of the primary pulley or the secondary pulley, these A hydraulic control device for a belt-type continuously variable transmission that controls a plurality of solenoid valves with a plurality of solenoid valves,
A valve for reducing the line pressure to a constant pressure and outputting it;
One solenoid of the plurality of solenoid valves inputs the constant pressure and receives all of the signal pressure to the line pressure control valve, the starting clutch pressure, and the signal pressure to the belt clamping pressure control valve. The belt clamping pressure control valve outputs the supply pressure from the oil pump as the clamping pressure to the belt by the input of the signal pressure by the one solenoid;
A failure determination means for determining whether or not the one solenoid valve has failed to the high pressure side is provided, and when it is determined that the failure determination means has failed to the high pressure side, the output pressure of the one solenoid valve is released. Maintain state,
A fail-safe switching valve is provided in an oil passage between the one solenoid valve and the line pressure control valve, and the switching valve is configured to detect the signal pressure from the one solenoid valve to the line pressure control valve and the line pressure control valve. When a constant pressure is input and the fail determination means determines that the high pressure side has failed, the output pressure to the line pressure control valve is switched to the constant pressure,
Means for achieving a desired gear ratio by a solenoid valve for controlling the speed change control valve;
A hydraulic control device for a belt-type continuously variable transmission.