JP2008106812A - Hydraulic control device of belt continuously variable transmission for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device of a belt continuously variable transmission for a vehicle capable of increasing shift speeds of pulley ratios in deceleration. <P>SOLUTION: This hydraulic control device of a belt continuously variable transmission for a vehicle comprises a first selector valve 33a for switching between the supply and discharge of a hydraulic oil to and from a primary pulley, a second selector valve 33d for switching between the supply of the hydraulic oil discharged from the first selector valve to a pressure-keeping valve 33b for keeping the hydraulic pressure of the hydraulic oil at a predetermined pressure or higher and the discharge of the hydraulic oil to a tank 36 for storing the hydraulic oil bypassed through the pressure-keeping valve, and a control unit 40 for switching the second selector valve according to the deceleration of the vehicle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in a hydraulic control device for a belt type continuously variable transmission for a vehicle.

  In a conventional belt-type continuously variable transmission for a vehicle, when a sudden deceleration is detected, the pulley ratio is changed to the lowest pulley ratio, which is the lowest pulley ratio, in preparation for restart (see Patent Document 1).

  In the invention described in Patent Document 1, it is disclosed that when the vehicle deceleration is large, the target pulley ratio is set to the lowest and the gear change speed is increased to shift to the lowest before the vehicle stops.

In addition, as a gear ratio control mechanism for a belt-type continuously variable transmission, the belt contact radius of the primary pulley is changed by a link mechanism that connects the step motor and the primary pulley, and the spool is displaced by the link mechanism to move to the primary pulley. There is one that is performed by a shift control valve that supplies and discharges hydraulic fluid. In such a mechanism, when the gear ratio control valve is displaced so as to discharge the hydraulic oil from the primary pool, the belt slip may occur if the hydraulic oil is suddenly discharged, and the hydraulic pressure that does not cause the belt slip is maintained. However, a pressure holding valve, an orifice, or the like that maintains the hydraulic pressure at a predetermined lower limit pressure is provided in the downstream oil passage of the discharge port so that the oil is discharged.
JP-A-11-13876

  Thus, in the prior art, it is necessary to secure a predetermined required oil pressure in order to prevent belt slippage, and the gear ratio speed of the pulley ratio is limited by this necessary oil pressure. If the speed change of the pulley ratio is limited, it is considered that if the deceleration is large, the pulley ratio cannot be changed to the lowest speed before the vehicle stops from the traveling speed. In such a case, at the time of re-starting, the vehicle starts with a pulley ratio higher than the lowest, so that the starting performance is lowered and the drivability is deteriorated.

  Therefore, an object of the present invention is to provide a hydraulic control device for a belt-type continuously variable transmission for a vehicle that increases the speed of a pulley ratio while preventing belt slippage.

  The present invention is wound around an input-side primary pulley whose groove width changes according to oil pressure, an output-side secondary pulley whose groove width changes according to oil pressure, the primary pulley and the secondary pulley, Supply and discharge of hydraulic fluid in the primary pulley in a hydraulic control device for a belt-type continuously variable transmission for a vehicle having a belt-type continuously variable transmission having a V-belt whose pulley contact radius changes according to a groove width. The first switching valve that switches between the two and the hydraulic oil discharged from the first switching valve is supplied to a pressure-holding valve that maintains the hydraulic pressure of the hydraulic oil at or above a predetermined hydraulic pressure, or the hydraulic pressure is bypassed and the hydraulic oil is bypassed. And a control unit that switches the second switching valve based on the deceleration of the vehicle. A hydraulic control device for a vehicular belt-type continuously variable transmission according to symptoms.

  Since the present invention has such a configuration, it is possible to promote the discharge of the hydraulic oil from the primary pulley and improve the speed change of the primary pulley.

  FIG. 1 is a schematic diagram showing a v-belt continuously variable transmission system for a vehicle according to the present invention.

  A v-belt type continuously variable transmission system 1 for a vehicle includes a clutch unit 10, a V-belt type continuously variable transmission unit 20, a hydraulic pressure adjusting unit 30, and a control unit 40, and reduces the rotation of an engine 60 to drive wheels. 70. Further, in the vehicle belt type continuously variable transmission system 1 of the present embodiment, a torque converter (hereinafter abbreviated as “torque converter”) 50 is provided between the engine 60 and the clutch unit 10. The torque converter 50 includes a turbine, an impeller, a stator, and the like, and is a device that transmits the rotational torque of the engine 60 by the flow of oil filled therein.

Assuming that the engine speed Ne, the torque converter capacity coefficient τ, and the torque converter torque ratio t, the input torque T _{in to} the torque converter 50 and the output torque T _out from the torque converter 50 are respectively
T _in = τ × Ne ²
T _out = τ × Ne ² × t
Is represented. Thus, the transmission torque of the torque converter 50 is determined by the engine speed.

  The clutch unit 10 includes a planetary gear 11 that switches a power transmission path between the engine 60 side and the primary pulley 21 side, a forward clutch 12, and a reverse brake 13, and by hydraulic pressure supplied from the clutch pressure adjusting device 35, The forward clutch 12 is engaged when the vehicle moves forward, the reverse brake 13 is engaged when the vehicle moves backward, and both the forward clutch 12 and the reverse brake 13 are released at the neutral position (neutral or parking). The clutch pressure adjusting device 35 controls the engagement state by adjusting the hydraulic pressure (forward clutch pressure, reverse clutch pressure) supplied to the forward clutch 12 and the reverse brake 13 in accordance with a command from the control unit 40.

  The forward clutch 12 and the reverse brake 13 are engaged exclusively, and at the time of forward movement (range signal = D range), the forward clutch pressure is supplied to fasten the forward clutch 12, and the reverse clutch pressure is connected to the drain. To release the reverse brake 13. On the other hand, at the time of reverse (range signal = R range), the forward clutch pressure is connected to the drain, the forward clutch 12 is released, the reverse clutch pressure is supplied, and the reverse brake 13 is engaged. In the neutral position (range signal = N range), the forward clutch pressure and the reverse clutch pressure are connected to the drain, and both the forward clutch 12 and the reverse brake 13 are released.

  The V-belt type continuously variable transmission unit 20 includes a primary pulley 21, a secondary pulley 22, and a V-belt 23.

  The primary pulley 21 is a pulley on the input shaft side that inputs the rotation of the engine 60. The primary pulley 21 has a fixed conical plate 21a that rotates integrally with the input shaft 21c, a V-shaped pulley groove that is disposed opposite to the fixed conical plate 21a, and a hydraulic pressure that acts on the primary pulley (hereinafter referred to as the hydraulic pulley). And a movable conical plate 21b that can be displaced in the axial direction by "primary pressure". The rotation speed of the primary pulley 21 is detected by a primary pulley rotation speed sensor 41.

  The secondary pulley 22 transmits the rotation transmitted by the V-belt 23 to the drive wheel 70 via an idler gear or a differential gear. The secondary pulley 22 has a fixed conical plate 22a that rotates integrally with the output shaft 22c, a V-shaped pulley groove disposed opposite to the fixed conical plate 22a, and a hydraulic pressure that acts on the secondary pulley 22 ( (Hereinafter referred to as “secondary pressure”) and a movable conical plate 22b that can be displaced in the axial direction. Note that the pressure receiving area of the secondary pulley and the pressure receiving area of the primary pulley are the same or substantially the same. The rotational speed of the secondary pulley 22 is detected by a secondary pulley rotational speed sensor 42. The vehicle speed is calculated from the rotational speed of the secondary pulley 22.

  The V belt 23 is wound around the primary pulley 21 and the secondary pulley 22, and transmits the rotation of the primary pulley 21 to the secondary pulley 22.

  The hydraulic pressure adjustment unit 30 includes a hydraulic pump 31, a line pressure adjustment device 32, a primary pressure adjustment device 33, a secondary pressure adjustment device 34, and a clutch pressure adjustment device 35.

  The hydraulic pump 31 is connected to the input side of the clutch unit 10 and is driven by the engine 60 to pump oil in the tank 36.

  The line pressure adjusting device 32 adjusts the pressure of the oil pumped from the hydraulic pump 31 to a predetermined line pressure according to the operation state by a command (for example, a duty signal) from the control unit 40.

  The primary pressure adjusting device 33 is a device that controls the primary pressure. For example, as shown in FIG. 2, the spool is displaced by a link mechanism including a solenoid, a servo link that constitutes a mechanical feedback mechanism, and a step motor. A first switching valve 33a, a pressure maintaining valve 33b that maintains the minimum required hydraulic pressure (= the lower limit hydraulic pressure that does not cause slippage between the primary pulley 21 and the V belt 23) acting on the primary pulley 21, and the primary pulley 21. And an orifice 33c for limiting the discharge speed at the time of discharging the hydraulic oil for lowering the hydraulic pressure acting on the engine. Furthermore, when the hydraulic oil is discharged from the primary pulley 21 (when the primary pressure is reduced) and the vehicle deceleration exceeds a predetermined deceleration, the discharged hydraulic oil is retained as described above. A second switching valve 33d that returns to the tank 36 without passing through the pressure valve 33b and the orifice 33c is provided.

  In FIG. 1, the secondary pressure adjusting device 34 is controlled by a command from the control unit 40, and further reduces the line pressure adjusted by the line pressure adjusting device 32 to a predetermined secondary pressure corresponding to the operating state. .

  The clutch pressure adjusting device 35 adjusts the forward clutch pressure and the reverse clutch pressure using the hydraulic pressure from the hydraulic pump 31 as a source pressure. The clutch pressure adjusting device 35 adjusts the forward clutch pressure and the reverse clutch pressure according to the hydraulic pressure command value of the control unit 40 to engage or release the forward clutch 12 and the reverse brake 13.

  The control unit 40 is a driving state such as a vehicle speed signal from the secondary pulley rotational speed sensor 42, a range signal from the inhibitor switch 43 that responds to the shift lever, an engine rotational speed signal from the engine 60 (or engine control device), and the like. Based on the above, a hydraulic pressure command value is determined and commanded to the clutch pressure adjusting device 35. The inhibitor switch 43 shows an example of selecting one of forward (D range), neutral position = neutral (N range), and reverse (R range).

  The control unit 40 controls the clutch pressure adjusting device 35 to adjust the hydraulic pressure supplied to the forward clutch 12 and the reverse brake 13 to control the forward clutch pressure and the reverse clutch pressure to control the engagement state of the clutch. .

  Further, the control unit 40 determines the input torque information, the ratio between the rotation speed of the primary pulley and the rotation speed of the secondary pulley (pulley ratio), the select position from the inhibitor switch 43, the vehicle speed (secondary pulley rotation speed), the depression of the accelerator pedal. The target pulley ratio is determined by reading signals such as quantity, oil temperature, oil pressure, etc., and the target pressures for primary and secondary pressures to achieve the target pulley ratio are calculated, and the target pressure is corrected as necessary. Then, the line pressure adjusting device 32, the primary pressure adjusting device 33, and the secondary pressure adjusting device 34 are controlled so as to be in accordance with the target pressure, and the hydraulic pressure supplied to the primary pulley 21 and the secondary pulley 22 is adjusted to adjust the movable cone. The plate 21b and the movable conical plate 22b are reciprocated in the direction of the rotation axis to move the primary pulley 21 and the secrecy Varying the pulley groove width of Daripuri 22. Then, the V belt 23 moves on the primary pulley 21 and the secondary pulley 22, the contact radius of the V belt 23 with respect to the primary pulley 21 and the secondary pulley 22 changes, and the pulley ratio is controlled.

  The rotation of the engine 60 is input to the belt-type continuously variable transmission unit 20 via the torque converter 50 and the clutch unit 10, and is transmitted from the primary pulley 21 to the driving wheel 70 via the V belt 23 and the secondary pulley 22.

  When the accelerator pedal is depressed or the shift change is performed in the manual mode, the control unit 40 displaces the movable conical plate 21b of the primary pulley 21 and the movable conical plate 22b of the secondary pulley 22 in the axial direction, By changing the contact radius, the pulley ratio is continuously changed.

  Further, the control unit 40 controls the engine torque and the rotational speed by controlling the fuel injection amount and throttle opening of the engine 60.

  Next, details of the primary pressure adjusting device 33 will be described with reference to FIG.

  As described above, the primary pressure adjusting device 33 is installed upstream of the first switching valve 33a, the pressure holding valve 33b that keeps the hydraulic pressure of the hydraulic fluid flowing through the first switching valve 33a at a predetermined hydraulic pressure or higher, and the pressure holding valve 33b. An orifice 33c and a second switching valve 33d installed between the first switching valve 33a and the orifice 33c are provided. The first switching valve 33a is a three-port two-position switching valve. The port a is connected to the primary pulley 21, the port b is connected to the hydraulic pump 31, the port c discharges hydraulic fluid, and the second switching valve. Connect to port d of 33d. The first and second switching valves 33a and 33d are switched and controlled by the control unit 40.

  When the pulley ratio is reduced, that is, when shifting to the speed increasing side, the hydraulic fluid from the hydraulic pump 31 is supplied to the primary pulley 21 by connecting the port a and the port b of the first switching valve 33a to the primary pulley 21. The contact radius of the V belt 23 at the pulley 21 is increased.

  On the other hand, when the pulley ratio is increased, that is, when shifting to the deceleration side, the port a and the port c of the first switching valve 33a are communicated with each other so that the hydraulic oil acting on the primary pulley 21 is supplied to the downstream second switching valve. Discharge to 33d. As a result, the primary pressure is reduced, the contact radius of the V belt 23 at the primary pulley 21 is reduced, and the pulley ratio is greatly changed.

  Similar to the first switching valve 33a, the second switching valve 33d to which the hydraulic oil discharged from the first switching valve 33a is supplied is constituted by a three-port two-position switching valve, and the port d is the first switching valve 33a. The port d connected to the port c and discharging the hydraulic oil is connected to the pressure holding valve 33b through the downstream orifice 33c, and the port e discharging the hydraulic oil is connected to the tank 36 storing the hydraulic oil.

  The control unit 40 determines whether or not the deceleration input from the vehicle acceleration / deceleration detecting means (not shown) exceeds a predetermined deceleration, and controls the switching of the second switching valve 33d. Here, the predetermined deceleration means that the pulley ratio is changed to the predetermined pulley ratio at the next start, usually the lowest, during the time from the current traveling vehicle speed to the stop at this deceleration. This is a deceleration that cannot be performed, and is set in advance by experiments or the like and stored in the control unit 40. Therefore, the predetermined deceleration may be changed according to the vehicle speed. The means for detecting or estimating the acceleration / deceleration of the vehicle may be an acceleration / deceleration sensor provided in advance in the vehicle, or the change in the calculated depression speed or vehicle speed is calculated by calculating the depression speed or the vehicle speed of the brake pedal. From this, the deceleration may be estimated.

  When the deceleration of the vehicle is equal to or lower than the predetermined deceleration, the second switching valve 33d communicates the port d and the port e, and the hydraulic oil passes through the orifice 33c and the pressure holding valve 33b and is discharged to the tank 36. Is done. In this case, since the hydraulic oil passes through the orifice 33c and the pressure holding valve 33b, the rate of decrease of the hydraulic pressure in the primary pulley 21 is limited by the action of the orifice 33c, and the pressure decrease in the primary pulley 21 is suppressed by the pressure holding valve 33b. Due to the action, the oil pressure is maintained at a predetermined hydraulic pressure or higher. Here, the predetermined hydraulic pressure is set to a lower limit hydraulic pressure that does not cause slippage between the primary pulley 21 and the V-belt 23. As described above, when the deceleration of the vehicle is equal to or lower than the predetermined deceleration, the hydraulic pressure of the hydraulic oil of the primary pulley 21 and the decrease speed of the hydraulic pressure of the hydraulic oil are limited, and the hydraulic pressure acting on the primary pulley 21 is set to the lower limit hydraulic pressure. Control is performed so that the V belt 23 is not slipped.

  On the other hand, when the deceleration of the vehicle exceeds the predetermined deceleration, the second switching valve 33d communicates the port d and the port f, and the hydraulic oil in the primary pulley 21 is the orifice 33c and the pressure holding valve 33b. Are discharged directly to the tank 36 without passing through. In this case, since the discharged hydraulic oil does not receive the resistance of the orifice 33c or the like, the discharge speed of the hydraulic oil is high, and the shift speed of the primary pulley 21 can be increased. As a result, even when the vehicle deceleration exceeds a predetermined deceleration, the pulley ratio can be set to the lowest level before the vehicle stops. In the case of performing the shift control at the time of sudden deceleration, the forward clutch 12 is not engaged when the vehicle is moving forward, or the reverse brake 13 is not engaged when the vehicle is moving backward.

  Therefore, according to the present invention, in the hydraulic control apparatus for a belt type continuously variable transmission for a vehicle, the first switching valve 33a for switching the supply and discharge of the hydraulic oil of the primary pulley 21 and the operation discharged from the first switching valve 33a. A second switching valve 33d for switching whether the hydraulic oil is supplied to a pressure-holding valve 33b that maintains the hydraulic pressure of the hydraulic oil at or above a predetermined hydraulic pressure, or whether the hydraulic oil is discharged to a tank 36 that stores the hydraulic oil; And a control unit 40 for switching the second switching valve 33d. Therefore, when the deceleration exceeds a predetermined deceleration, the hydraulic oil is supplied from the primary pulley 21 to the first switching valve 33a to the second switching valve. 33d to the tank 36, the pressure keeping valve 33b, and the orifice 33c are allowed to flow without passing therethrough, and the discharge of the hydraulic oil in the primary pulley 21 is promoted. For this reason, when the deceleration exceeds a predetermined deceleration, it is possible to improve the shift speed of the primary pulley 21 and to reliably shift to a predetermined speed ratio, for example, the lowest before the vehicle stops. On the other hand, when the deceleration is equal to or lower than the predetermined deceleration, the minimum hydraulic pressure acting on the primary pulley is compensated by the pressure holding valve, and the slip between the V belt 23 and the primary pulley 21 can be reliably prevented.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea of the present invention.

1 is a schematic configuration diagram showing a belt type continuously variable transmission system for a vehicle according to the present invention. It is a block diagram explaining the detailed structure of a primary pressure regulator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle belt type continuously variable transmission system 10 Clutch part 20 Belt type continuously variable transmission part 21 Primary pulley 22 Secondary pulley 23 V belt 30 Hydraulic adjustment part 31 Hydraulic pump 32 Line pressure adjustment apparatus 33 Primary pressure adjustment apparatus 33a 1st switching valve 33b Pressure holding valve 33c Orifice 33d Second switching valve 34 Secondary pressure adjustment device 35 Clutch pressure adjustment device 36 Tank 40 Control unit 41 Primary pulley rotation speed sensor 42 Secondary pulley rotation speed sensor 50 Torque converter 60 Engine 70 Drive wheel

Claims (5)

It is wound around an input-side primary pulley whose groove width changes according to the oil pressure, an output-side secondary pulley whose groove width changes according to the oil pressure, the primary pulley and the secondary pulley, and according to the groove width. A vehicle belt-type continuously variable transmission hydraulic control device having a belt-type continuously variable transmission including a V-belt whose pulley contact radius changes.
A first switching valve for switching between supply and discharge of hydraulic oil in the primary pulley;
Whether the hydraulic oil discharged from the first switching valve is supplied to a pressure holding valve that maintains the hydraulic pressure of the hydraulic oil at a predetermined pressure or higher, or is discharged to a tank that stores the hydraulic oil by bypassing the pressure holding valve A second switching valve for selectively switching between,
A control unit that switches the second switching valve based on the deceleration of the vehicle;
A hydraulic control device for a belt-type continuously variable transmission for a vehicle.   The control unit directly discharges hydraulic oil discharged from the first switching valve to the tank when the deceleration of the vehicle exceeds a predetermined deceleration, and when the vehicle is below a predetermined deceleration, 2. The hydraulic control device for a vehicle belt-type continuously variable transmission according to claim 1, wherein the second switching valve is switched so as to supply hydraulic oil discharged from the first switching valve to the pressure holding valve. .   The predetermined deceleration is a deceleration at which a pulley ratio of the belt-type continuously variable transmission cannot be shifted to a predetermined pulley ratio until the vehicle stops from a traveling vehicle speed. Item 3. A hydraulic control device for a belt type continuously variable transmission for vehicle according to Item 2.   2. The belt-type continuously variable transmission for a vehicle according to claim 1, wherein the predetermined hydraulic pressure held by the pressure-holding valve is a lower limit hydraulic pressure at which no slip occurs between the primary pulley and the V-belt. Hydraulic control device for the machine.   2. The hydraulic control apparatus for a belt type continuously variable transmission for a vehicle according to claim 1, wherein an orifice is provided between the pressure holding valve and the second switching valve.