JP2008039154A - Hydraulic control device for belt type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device for belt type continuously variable transmission, capable of surely preventing slip of a V-belt in the event of garage shift. <P>SOLUTION: When the garage shift is performed based on establishment of secondary pressure-side and primary pressure-side garage shift control transfer conditions, and the advancing direction of a changed shift range is different from the advancing direction of a vehicle by inertia of the vehicle or the like, a target secondary pressure calclulation part 101 and a target primary pressure calculation part 103 increase a target secondary pressure and a target primary pressure, respectively. According to this, the V-belt can be strongly held by a primary pulley and a secondary pulley, and the slip of the V-belt can be prevented. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

Conventionally, there is a belt-type continuously variable transmission using a V-belt as an automatic transmission mounted on a vehicle. In a belt-type continuously variable transmission, a V-belt is sandwiched between a primary pulley and a secondary pulley whose groove width is variably controlled based on hydraulic pressure, and power is transmitted by the contact friction force.
Such a belt type continuously variable transmission calculates a secondary pressure to be supplied to a hydraulic chamber provided in a secondary pulley from an input torque or the like determined by an engine speed and a throttle opening, and determines a secondary pressure based on a gear ratio or the like. The primary pressure supplied to the hydraulic chamber provided in the primary pulley is calculated from the pressure, and the secondary pressure and the line pressure that is the base pressure when generating the primary pressure are calculated. A gear ratio is achieved.
The belt-type continuously variable transmission includes a forward / reverse switching mechanism having a planetary gear mechanism as a component between the engine and the primary pulley, and switches the rotational direction of the engine by the forward / backward switching mechanism to transmit to the pulley. The vehicle is moving forward and backward.

  Here, when the vehicle speed is equal to or higher than a predetermined value, for example, when the vehicle is put in the garage, shift switching from the R range (reverse range) to the D range (forward range) or from the D range to the R range (hereinafter also referred to as garage shift). ), The traveling direction of the vehicle inertia may differ from the traveling direction of the range after switching. In this case, since the rotational direction of the primary pulley to which the rotational force switched by the forward / reverse switching mechanism is transmitted and the secondary pulley to which the rotational force of the vehicle inertia is transmitted are different, the V belt may slip. is there.

In order to prevent this, for example, what is described in Patent Document 1 is that when the throttle opening is low and the vehicle speed is low, the primary pressure and the secondary pressure are set higher in advance to increase the holding force of the V belt and slip. Is preventing.
Moreover, in what was described in patent document 2, when it is detected that the primary pulley and the secondary pulley are rotating in reverse, the torque capacity of the primary pulley is compared by comparing the input torque and the torque capacity of the primary pulley. The slippage of the V belt is prevented by calculating the shortage and correcting the line pressure (correction in the upward direction).
JP 2004-84787 A JP 2004-84755 A

However, what is described in Patent Document 1 is that the original purpose is to prevent the V-belt from slipping due to the transmission of reverse torque due to the curb ride, so that the hydraulic pressure is always based on the throttle opening and the vehicle speed. Therefore, there is a problem that the fuel consumption is deteriorated.
In addition, the sensor described in Patent Document 2 must be provided with a sensor for detecting the reverse rotation between the primary pulley and the secondary pulley, and the line pressure increases after detecting the reverse rotation between the pulleys. Since the direction is corrected, there is a problem that the control response is slow.

  Accordingly, an object of the present invention is to provide a hydraulic control device in a belt-type continuously variable transmission that can reliably prevent slippage of a V-belt when a garage shift occurs.

  The present invention relates to a range position switching means for switching between a forward range position and a reverse range position, a vehicle speed sensor for detecting a vehicle speed, and a forward / backward movement for switching forward / reverse movement of a vehicle by engaging a forward clutch or a reverse clutch according to the range position switching means. In a hydraulic control device for a belt-type continuously variable transmission that calculates a primary pressure and a secondary pressure using a hydraulic pressure obtained from an engine torque and a target gear ratio as a base pressure and performs a shift using the primary pressure and the secondary pressure. When the forward range position or the reverse range position is selected by the position switching means and the vehicle speed is equal to or higher than the predetermined value, the primary pressure and the secondary pressure are corrected to be higher than the normal time until the completion of the engagement of the forward clutch or the reverse clutch. It was supposed to be.

  According to the present invention, when the vehicle is at a predetermined speed when the forward range position or the reverse range position is selected, that is, when the traveling direction of the range after switching is different from the traveling direction due to the inertia of the vehicle, Since the pressure and the secondary pressure are corrected to be higher than those at the normal time, the belt can be strongly held by the primary pulley and the secondary pulley, and the belt can be prevented from slipping.

Next, embodiments of the present invention will be described by way of examples.
FIG. 1 shows a schematic configuration in which the present invention is applied to a belt-type continuously variable transmission.
In FIG. 1, a belt type continuously variable transmission 3 including a transmission mechanism unit 5 having a forward / reverse switching mechanism 4 and a torque converter 2 having a lock-up clutch is connected to an engine 1. The transmission mechanism unit 5 includes a primary pulley 10 on the input shaft side as a pair of variable pulleys and a secondary pulley 11 connected to the output shaft 13. The pair of variable pulleys 10 and 11 are connected by a V belt 12. The output shaft 13 is connected to the differential 6 via an idler gear 14.

  The transmission ratio of the transmission mechanism 5 and the contact frictional force of the V-belt 12 are controlled by a hydraulic control unit 50 that operates according to a command from the CVT control unit 20. The CVT control unit 20 is connected to an engine control unit (hereinafter referred to as ECU) 30 that controls the engine 1 and exchanges information with each other. The CVT control unit 20 receives the throttle opening (TVO) from the throttle opening sensor 24, the engine speed from the ECU 30, and the like, and calculates the input torque from the engine.

In particular, the CVT control unit 20 includes a pulley pressure control unit 21 for controlling the hydraulic pressure supplied to each pulley 10, 11 and a forward / reverse switching control unit 22 for controlling the hydraulic pressure supplied to the forward / reverse switching mechanism 4. Prepare.
The forward / reverse switching mechanism 4 includes a forward clutch 4A that transmits engine rotation to the transmission mechanism unit 5 as rotation in the vehicle forward direction by hydraulic pressure supplied by the forward / reverse switching control unit 22 controlling the hydraulic control unit 50. A reverse clutch 4B that transmits engine rotation as rotation in the vehicle reverse direction, and switches the vehicle forward and backward by the supplied hydraulic pressure.

An oil pump 7 driven by the engine is provided, and the oil pump 7 pressurizes oil accumulated in an oil pan (not shown) provided below the belt-type continuously variable transmission 3 and supplies the pressurized oil to the hydraulic control unit 50. .
An inhibitor switch 23 for detecting the operation position of the shift lever is provided, and information on the operation position of the shift lever detected by the inhibitor switch 23 is input to the CVT control unit 20.

  The primary pulley 10 and the secondary pulley 11 are respectively provided with a primary pulley rotation speed sensor 26 and a secondary pulley rotation speed sensor 27, and the detected values thereof are input to the CVT control unit 20. The CVT control unit 20 can calculate the pulley ratio from the detection values of the primary pulley rotation speed sensor 26 and the secondary pulley rotation speed sensor 27. The CVT control unit 20 calculates the vehicle speed from the detection value of the secondary pulley rotation speed sensor 27.

The primary pulley 10 of the transmission mechanism unit 5 is disposed at a position opposed to the fixed conical plate 10b that rotates integrally with the input shaft and the fixed conical plate 10b to form a V-shaped pulley groove. The movable conical plate 10a can be displaced in the axial direction in accordance with a hydraulic pressure (hereinafter referred to as primary pressure) acting on the cylinder chamber 10c.
The secondary pulley 11 is disposed at a position opposed to the fixed conical plate 11b that rotates integrally with the output shaft 13 and the fixed conical plate 11b to form a V-shaped pulley groove, and to the secondary pulley cylinder chamber 11c. It is composed of a movable conical plate 11a that can be displaced in the axial direction in accordance with the acting hydraulic pressure (hereinafter referred to as secondary pressure).

  The input torque input from the engine 1 is input to the primary pulley 10 via the torque converter 2 and the forward / reverse switching mechanism 4, and is transmitted from the primary pulley 10 to the secondary pulley 11 via the V belt 12. By moving the movable conical plate 10a of the primary pulley 10 and the movable conical plate 11a of the secondary pulley 11 in the axial direction and changing the contact radius between the V belt 12 and the pulleys 10 and 11, the primary pulley 10 and the secondary pulley 11 can be continuously changed.

Next, a procedure for calculating the primary pressure and the secondary pressure by the pulley control unit 21 of the CVT control unit 20 in a steady state will be described.
FIG. 2 shows a control block diagram of the primary pressure and the secondary pressure.
The input torque calculation unit 100 calculates the input torque input to the belt type continuously variable transmission 3 from the throttle opening (TVO) from the throttle opening sensor 24 and the engine speed from the ECU 30.
The target gear ratio calculation unit 102 calculates the target gear ratio from the throttle opening (TVO) and the vehicle speed detected by the secondary pulley rotation speed sensor 27.

The target secondary pressure calculation unit 101 calculates a target secondary pressure from the input torque calculated by the input torque calculation unit 100 and the target speed ratio calculated by the target speed ratio calculation unit 102.
The target primary pressure calculation unit 103 includes the input torque calculated by the input torque calculation unit 100, the target secondary pressure calculated by the target secondary pressure calculation unit 101, and the target gear ratio calculated by the target gear ratio calculation unit 102. Thus, the target primary pressure is calculated.

The correction coefficient calculation unit 105 calculates various correction coefficients.
This correction coefficient corrects, for example, a deviation between the actual pulley position and the target pulley position calculated from the target gear ratio.
The secondary pressure correction unit 104 corrects the target secondary pressure calculated by the target secondary pressure calculation unit 101 using the correction coefficient calculated by the correction coefficient calculation unit 105.
The primary pressure correction unit 106 corrects the target primary pressure calculated by the target primary pressure calculation unit 103 using the correction coefficient calculated by the correction coefficient calculation unit 105.

The secondary pressure control unit 107 instructs the hydraulic pressure control unit 50 to control the primary pressure so that the corrected target secondary pressure calculated by the secondary pressure correction unit 104 is obtained.
The primary pressure control unit 108 instructs the hydraulic pressure control unit 50 to control the secondary pressure so that the corrected target primary pressure calculated by the primary pressure correction unit 106 is obtained.

The CVT control unit 20 calculates, as the line pressure, a value obtained by adding a predetermined value to the higher hydraulic pressure value among the calculated secondary pressure and primary pressure.
The hydraulic control unit 50 is provided with a pressure regulating valve that regulates the hydraulic pressure output from the oil pump 7. The hydraulic control unit 50 outputs from the oil pump 7 so that the line pressure calculated by the CVT control unit 20 is obtained. The line pressure is generated by adjusting the hydraulic pressure.
The hydraulic control unit 50 generates a primary pressure and a secondary pressure by adjusting the line pressure.

Next, hydraulic control performed by the pulley control unit 21 when there is a shift switching (garage shift) from the R range to the D range or from the D range to the R range will be described.
In addition, since the hydraulic control is the same at the time of shift switching from the R range to the D range in the garage shift and at the time of shift switching from the D range to the R range, there is a shift switching from the R range to the D range here. The hydraulic control in this case will be described as a representative.
Here, it is assumed that the driver of the vehicle is performing a garage shift while the accelerator is depressed (accelerator ON state) and the brake is not depressed (brake OFF state).

The target secondary pressure calculation procedure performed by the target secondary pressure calculation unit 101 and the target primary pressure calculation procedure performed by the target primary pressure calculation unit 103 when there is a garage shift will be described.
First, the procedure for calculating the target secondary pressure will be described.
FIG. 3 is a diagram showing a calculation procedure of the target secondary pressure performed by the target secondary pressure calculation unit 101, and FIG. 4 is a time chart showing the operation of each unit.
It is assumed that there is a shift switch from the R range to the D range while the vehicle is moving backward. Further, the shift switching is assumed to be switched from the R range to the D range via the N range. Furthermore, it is assumed that the traveling direction of the vehicle is switched from backward to forward at time t5 in FIG.

In step 200, the target secondary pressure calculation unit 101 determines whether the secondary pressure side garage shift control transition condition is satisfied.
Here, the secondary pressure side garage shift control transition condition is whether there is a garage shift (in this case, shift switching from the R range to the D range) and whether the vehicle speed is 3 km / h or more and 20 km / h or less. to decide.

If the secondary pressure side garage shift control transition condition is satisfied, the process proceeds to step 201, and if not, the process proceeds to step 203.
In FIG. 4, at the time t1 when the vehicle is moving backward, the shift switching from the R range to the D range is started, and at the time t2 when the shift range becomes the D range via the N range, the secondary pressure side garage shift control transition condition Is established.
The vehicle speed used by the target secondary pressure calculation unit 101 for determining whether or not the secondary pressure-side garage shift control transition condition is satisfied uses the absolute value of the vehicle speed, and in FIG. 4, the vehicle speed is shown as an absolute value.

If it is determined that the secondary pressure side garage shift control transition condition is satisfied at time t2 in FIG. 4, in step 201, the target secondary pressure is raised.
The target secondary pressure increase control is to increase the target secondary pressure to the oil amount balance limit of the oil pump 7 driven by the engine 1.
The increase control of the target secondary pressure is within the strength limit of the V belt 12.

During the increase control of the target secondary pressure, the target secondary pressure calculation unit 101 outputs the calculated target secondary pressure (oil amount balance limit pressure of the oil pump 7) to the secondary pressure control unit 107.
Accordingly, the secondary pressure correction unit 104 does not correct the target secondary pressure, and the secondary pressure can be increased. In addition, the target secondary pressure in the steady state (secondary pressure in the steady state) is indicated by a broken line.

Here, when the shift range becomes the D range, the forward / reverse switching control unit 22 in the CVT control unit 20 performs control for fastening the forward clutch 4A of the forward / reverse switching mechanism 4.
Therefore, after time t2 in FIG. 4, the pulley control unit 21 gradually increases the target value (target forward clutch pressure) of the hydraulic pressure supplied to the forward clutch 4A.
Although not shown, the reverse clutch 4B is released by lowering the target reverse clutch pressure, which is the target value of the hydraulic pressure supplied to the reverse clutch 4B, contrary to the increase of the target forward clutch pressure.

Immediately after switching to the D range, the forward clutch piston oil chamber is not filled with oil.
Therefore, in order to improve the responsiveness of the forward clutch, as shown in FIG. 4, the target forward clutch pressure is set to a large value (precharge pressure) until a predetermined time elapses from time t2 immediately after switching to the D range (until time t3). ).
In addition, after the engagement of the forward clutch is completed, the hydraulic pressure for maintaining the engaged state is supplied.

After raising the target secondary pressure, in step 202, it is determined whether or not the secondary pressure side garage shift control transition condition is not satisfied.
Specifically, it is determined that the secondary pressure-side garage shift control transition condition has not been established when the vehicle speed is no longer than 3 km / h and no more than 20 km / h, or when the range is no longer the D range. .
While the secondary pressure side garage shift control transition condition is satisfied, the target secondary pressure increase control in step 201 is continued, and when the secondary pressure side garage shift control transition condition is not satisfied, the process proceeds to step 203.

In step 203, the target secondary pressure in the steady state is calculated as described above.
Therefore, as shown in FIG. 4, the target secondary pressure calculation unit 101 calculates the target secondary pressure in the steady state after time t4 when the vehicle speed decreases and the secondary pressure side garage shift control transition condition is not satisfied.
Here, the target secondary pressure that has been increased to the oil amount balance limit pressure of the oil pump 7 is gradually decreased from time t4 to the target secondary pressure in a steady state.
After calculation of the target secondary pressure at regular time, the process returns to step 200 and the above-described processing is repeated.

Next, the procedure for calculating the target primary pressure will be described.
FIG. 5 is a diagram illustrating a calculation procedure of the target primary pressure performed by the target primary pressure calculation unit 103.
In step 300, the target primary pressure calculation unit 103 determines whether or not the primary pressure side garage shift control transition condition is satisfied.
Here, the primary pressure side garage shift control transition condition is that there is a garage shift, the vehicle speed is 1 km / h or more and 20 km / h or less, and the forward clutch 4A of the forward / reverse switching mechanism 4 is released. Determine whether or not.
The control state of the forward clutch 4A and the reverse clutch 4B performed by the forward / reverse switching control unit 22 is input to the pulley control unit 21, and the target primary pressure calculation unit 103 refers to the input control state of the forward clutch 4A. To determine whether or not the forward clutch 4A is released.

When the primary pressure side garage shift control transition condition is satisfied, the routine proceeds to step 301, and when it is not satisfied, the routine proceeds to step 303.
In FIG. 4, when the shift switching from the R range to the D range is started at time t1, and the shift range becomes the D range at time t2, the target primary pressure is raised in step 301.

The target primary pressure calculated in the target primary pressure increase control is calculated by the following equation using the target secondary pressure calculated by the target secondary pressure calculation unit 101.
Target primary pressure = Target secondary pressure × Hydraulic ratio The hydraulic ratio is calculated from the map shown in FIG. 6 using the target transmission ratio calculated by the target transmission ratio calculation unit 102.
As shown in FIG. 6, the hydraulic pressure ratio is set to a value that increases as the target gear ratio changes from the Hi side (high speed side) to the Low side (low speed side).

During the target primary pressure increase control, the target primary pressure calculation unit 103 outputs the calculated target primary pressure (a value calculated from the hydraulic pressure ratio and the target secondary pressure) to the primary pressure control unit 108.
Accordingly, the primary pressure correction unit 106 does not correct the target primary pressure, and the primary pressure can be increased after time t2.
In addition, the target primary pressure at the normal time (primary pressure at the normal time) is indicated by a broken line.

After raising the target primary pressure, in step 302, it is determined whether or not the primary pressure side garage shift control transition condition is not satisfied.
Specifically, when the speed of the vehicle is not higher than 1 km / h and lower than 20 km / h, the range is not the D range, or the forward clutch 4A of the forward / reverse switching mechanism 4 is engaged. Therefore, it is determined that the primary pressure side garage shift control transition condition is not satisfied.
While the primary pressure side garage shift control transition condition is satisfied, the target primary pressure increase control in step 301 is continued, and when the primary pressure side garage shift control transition condition is not satisfied, the routine proceeds to step 303.

In step 303, the target primary pressure in the steady state is calculated as described above.
Therefore, as shown in FIG. 4, the target primary pressure calculation unit 103 calculates the target primary pressure at the steady state after time t4 ′ when the vehicle speed decreases and the primary pressure garage shift control transition condition is not satisfied.
After calculation of the target primary pressure at regular time, the process returns to step 300 and the above-described processing is repeated.

  In the above description, the control when there is a shift switching from the R range to the D range as a garage shift has been described. However, when there is a shift switching from the D range to the R range, the target is the same as above. Increase control of the secondary pressure and the target primary pressure is performed.

As described above, when the garage shift control transition condition on the primary pressure side and the secondary pressure side is satisfied, the force by which the primary pulley 10 and the secondary pulley 11 clamp the V belt 12 is controlled by performing the increase control of the target secondary pressure and the target primary pressure. Increases and slippage of the V-belt 12 is prevented.
Therefore, the rotational force input to the belt type continuously variable transmission 3 from the axle side by the inertia of the vehicle is input to the forward / reverse switching mechanism 4 via the secondary pulley 11, the V belt 12, and the primary pulley 10.

The difference between the rotational force input to the belt type continuously variable transmission 3 from the engine 1 side and the rotational force input to the forward / reverse switching mechanism 4 from the axle side by the inertia of the vehicle is the forward clutch of the forward / reverse switching mechanism 4 Absorbed in 4A or reverse clutch 4B.
Here, the forward clutch 4A and the reverse clutch 4B are gradually engaged or released while sliding two friction plates having different rotational speeds as an original operation, and the forward clutch 4A applies rotational forces having different rotational directions. Even if it is absorbed in the reverse clutch 4B, there is no particular problem.

  As the forward clutch 4A approaches the fully engaged state from the disengaged state, the rotation input to the belt type continuously variable transmission 3 from the axle side by the inertia of the vehicle is weakened by the rotation of the engine 1, and the forward clutch 4A is completely When the engaged state is established, the rotational force of the engine 1 is transmitted to the axle. That is, the vehicle speed once becomes zero in the vicinity where the forward clutch is completely engaged.

  The present embodiment is configured as described above, the garage shift control transition condition on the secondary pressure side and the primary pressure side is established, the garage shift is present, the traveling direction of the shift range after the change, the traveling direction of the vehicle due to the vehicle inertia, etc. In such a case, by increasing the target secondary pressure and the target primary pressure, the V-belt 12 can be strongly held by the primary pulley 10 and the secondary pulley 11, and slippage of the V-belt 12 can be prevented. .

  The garage shift control transition condition on the secondary pressure side and the primary pressure side is not established as in the case where the vehicle speed is less than the predetermined value or the forward clutch 4A or the reverse clutch 4B of the forward / reverse switching mechanism 4 is engaged. In this case, since the calculation of the target secondary pressure and the target primary pressure is switched to the hydraulic pressure calculation control in the steady state, unnecessary oil pressure increase control is not performed, and the load on the oil pump 7 can be reduced. The fuel consumption of the engine 1 can be improved.

  Moreover, since the target secondary pressure at the time of the control for increasing the target secondary pressure is the oil amount balance limit pressure determined by the discharge capacity of the oil pump 7, the primary pulley 10 and the secondary pulley 11 strongly hold the V belt 12. Thus, slippage of the V-belt 12 can be reliably prevented.

It is a figure which shows schematic structure of a belt-type continuously variable transmission. It is a control block diagram of a primary pressure and a secondary pressure. It is a figure which shows the calculation procedure of target secondary pressure. It is a time chart which shows operation | movement of each part. It is a figure which shows the calculation procedure of target primary pressure. It is a figure which shows the relationship between a target gear ratio and a hydraulic ratio.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Torque converter 3 Belt type continuously variable transmission 4 Forward / reverse switching mechanism 4A Forward clutch 4B Reverse clutch 5 Transmission mechanism part 7 Oil pump 10 Primary pulley 11 Secondary pulley 12 V belt 20 CVT control unit 21 Pulley control part 22 Forward / backward movement Switching control unit 23 Inhibitor switch (Range position switching means)
24 Throttle opening sensor 26 Primary pulley rotation speed sensor 27 Secondary pulley rotation speed sensor 30 ECU
DESCRIPTION OF SYMBOLS 50 Hydraulic control unit 100 Input torque calculation part 101 Target secondary pressure calculation part 102 Target gear ratio calculation part 103 Target primary pressure calculation part 104 Secondary pressure correction part 105 Correction coefficient calculation part 106 Primary pressure correction part 107 Secondary pressure control part 108 Primary pressure Control unit

Claims (2)

Range position switching means for switching between the forward range position and the reverse range position;
A vehicle speed sensor for detecting the vehicle speed;
A forward / reverse switching mechanism for switching forward / backward movement of the vehicle by fastening a forward clutch or a reverse clutch according to the range position switching means;
In a hydraulic control device for a belt-type continuously variable transmission that calculates a primary pressure and a secondary pressure using a hydraulic pressure obtained from an engine torque and a target gear ratio as a base pressure, and performs a shift using the primary pressure and the secondary pressure,
When the forward range position or the reverse range position is selected by the range position switching means and the vehicle speed is equal to or higher than a predetermined value,
A hydraulic control apparatus for a belt-type continuously variable transmission, wherein the primary pressure and the secondary pressure are corrected to be higher than in a steady state until the completion of engagement of the forward clutch or the reverse clutch. The primary pressure and the secondary pressure are generated based on the hydraulic pressure discharged from the oil pump,
The belt-type continuously variable transmission according to claim 1, wherein the correction for making the secondary pressure higher than that in a steady state is made the oil pressure balance limit pressure determined by the discharge capacity of the oil pump. Hydraulic control device in the machine.

Images