JPH01220758A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE:To prevent response from delaying by immediately increasing line pressure in spite of intervention of a delaying means for only appointed time in correspondence to vehicle speed at that time, with a line pressure control means and a correcting means when engine brake is acted. CONSTITUTION:On judging respectively with an inhibitor switch 40 that a gear change mechanism is changed over to a change gear step on which engine brake is effective for being operated, and still with a throttle sensor 41 that accelerator is opened, a control unit 33 commands a line pressure adjusting means 32, as a requirement on engine braking to let a line pressure control means increase line pressure only for appointed time corresponding to signal from a vehicle speed sensor 42 via a correcting means. And the line pressure adjusting means 32 increases line pressure for coupling immediately a coasting clutch 12 in a gear change mechanism 3 in spite of intervention of a delaying means 38. Thus it can be done to dissolve response delay under requirement on engine braking and to prevent free run feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic control device for an automatic transmission.

(Prior Art) Conventionally, as a hydraulic control device for an automatic transmission, for example, as disclosed in Japanese Utility Model Application Publication No. 133149/1983, there has been a hydraulic control device for a power transmission and a transmission mechanism that switches the B path to multiple stages. Friction elements (e.g. forward clutch)
The forward clutch is connected to the output shaft side via a one-way clutch so that power is transmitted only from the engine side to the drive wheels, and the coasting clutch is connected directly to the output shaft side. It is known that the engine braking effect can be ensured by connecting the drive wheels to the engine to allow power transmission from the drive wheels to the engine.

By the way, as mentioned above, in the case of a transmission mechanism equipped with a friction element and a coasting clutch involved in transmission, when performing a transmission operation that involves engaging both of them (i.e., at a predetermined range position where engine braking is not required), (at automatic shift)
In order to ensure smooth transmission of power and prevent shift shock, the timing of engagement between the two is staggered. That is, first, the friction elements related to gear shifting are engaged, and then the coasting clutch is engaged. In other words, the supply of line pressure to the coasting clutch is delayed by intervening a throttling mechanism or the like, thereby delaying its engagement.

(Problem to be Solved by the Invention) As mentioned above, when the supply of line pressure to the coasting clutch is delayed by the intervention of a throttling mechanism, etc., the driver must consciously apply a large amount of engine braking. For example, when the gear is changed from D range to L range by operating the select lever, or when the hold switch is pressed down in 4th gear in D range to downshift to 3rd forward gear. Sometimes, the supply of line pressure to the coasting clutch is delayed due to the action of the throttling mechanism, etc., resulting in a delay in engagement of the coasting clutch, which impedes the immediate effectiveness of the engine brake. , a problem arises in that it gives the driver an unpleasant feeling of idling.

To solve this problem, it is possible to temporarily increase the line pressure when engine braking is requested, but if the line pressure increase time is set constant according to the state of high engine braking torque, In a state where the torque is small, the time becomes unnecessarily long, which is undesirable from the viewpoint of shift shock.

The present invention has been made in view of the above-mentioned points, and in a transmission mechanism equipped with a coasting clutch, only when the driver requests a large engine braking action, the line pressure is reduced for a period corresponding to the vehicle speed. By temporarily increasing the line pressure and setting the time corresponding to the engine brake torque, it is possible to prevent shift shock caused by increasing the line pressure for an unnecessarily long time, and to ensure the immediate effectiveness of the engine brake. The purpose is to

(Means for solving the problems) In the present invention, as means for solving the above problems,
A coasting clutch operates to achieve a gear position where engine braking is effective, a transmission mechanism switches a power transmission path to multiple stages, and when the coasting clutch is engaged, the supply of line pressure to the coasting clutch is delayed. In the hydraulic control device for an automatic transmission, the hydraulic control device is provided with a delay means that acts to delay the engagement of the line pressure, and a line pressure adjustment means that adjusts the line pressure, and the transmission mechanism is operated to switch to a gear position where engine braking is effective. an accelerator pedal operation determining means for determining whether or not the accelerator pedal is in the released state; and an accelerator pedal operation determining means for determining whether the accelerator pedal is in the released state; a line pressure control means for controlling the line pressure adjustment means to temporarily increase the line pressure for engaging the coasting clutch; and a correction means for correcting the time for increasing the line pressure by the line pressure control means in accordance with the vehicle speed. is attached.

(Function) In the present invention, the following effects can be obtained by the above means.

In other words, during automatic gear shifting in a predetermined range position selected by the select lever and without the need for engine braking, the friction elements involved in gear shifting (for example, the forward clutch)
When engaging both the coasting clutch and the coasting clutch, the supply of line pressure to the coasting clutch is delayed by the action of the delay means, resulting in a delay in the engagement operation, and the engagement of the friction elements involved in gear shifting is delayed due to coasting. This is done prior to engagement of the clutch, and the shift shock during the shift operation is effectively reduced. On the other hand, when the driver consciously requests a large engine braking effect by operating the selector lever to select the range position to the low speed side, and also by releasing the accelerator pedal, the line pressure control means and correction means operate. As a result, the line pressure is increased for a predetermined time corresponding to the vehicle speed at that time, and the line pressure is immediately supplied to the coasting clutch regardless of the intervention of the delay means, thereby suppressing shift shock as much as possible. The coasting clutch is quickly engaged while the driver is moving.As a result, the large engine brake is quickly applied as per the driver's intention, and the driver does not feel the feeling of dry running.The above-mentioned pressure increase time is determined by the speed of the vehicle. It is expressed as a function and is read from a preset map.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 2 shows an automatic transmission with four forward speeds and one reverse speed, and the automatic transmission includes a pump 2a connected to the engine output shaft l, a turbine 2b facing the pump 2a,
A fluid converter 2 includes a stator 2c interposed between the pump 2a and the turbine 2b, a one-way clutch 2d for preventing the stator 2c from rotating in the opposite direction to the turbine 2b, and a turbine 2b of the fluid converter 2. connected to the connected converter output shaft 2e,
The transmission gear device 3 functions as a transmission mechanism that switches the power transmission path into multiple stages.

The speed change gear device 3 includes a planetary gear mechanism 4 therein. The planetary gear mechanism 4 includes a small-diameter sun gear 5 and a large-diameter sun gear 6 arranged in front and rear, a short pinion gear 7 that meshes with the small-diameter sun gear 5, and a long pinion gear 8 that meshes with the large-diameter sun gear 6 and short pinion gear 7. It consists of a ring gear 9 that meshes with the long pinion gear 8. The small-diameter sun gear 5 is connected to the output shaft 2e of the fluid converter 2 via a forward clutch 10 and a first one-way clutch 11 arranged behind it, and a coasting shaft 2e provided in parallel with the forward clutch lO. clutch 12
The converter output shaft 2e is directly connected to the converter output shaft 2e. The first one-way clutch 2 is connected to a small diameter sun gear 5.
This acts to prevent the converter output shaft 2e from being driven in the reverse direction. Furthermore, when the coasting clutch 12 is engaged, the small-diameter sun gear 5 can perform an engine braking action to drive the converter output shaft 2e in the reverse direction. Further, the large diameter sun gear 6 is connected to the converter output shaft 2e via a 2-4 brake 13 disposed behind it and a reverse clutch 14 disposed behind the 2-4 brake 13.
is connected to. Furthermore, the long pinion gear 8
A low & reverse brake 16 acts to fix the long pinion gear 8 via a carrier 15 connected to the rear thereof, and a second brake that allows the long pinion gear 8 to rotate in the same direction as the engine output shaft l. A one-way clutch 17 is connected. On the other hand, the front portion of the long pinion gear 8 is connected to the converter output shaft 2e via a 3-4 clutch I9. In addition, the ring gear 9 has an output gear 20 disposed in front thereof.
is connected to. In FIG. 2, reference numeral 21 is a lock-up clutch that directly connects the engine output shaft l and the converter output shaft 2e, and 22 is an intermediate shaft disposed within the converter output shaft 2e. It is a driven oil pump.

In the above configuration, the operating states of each clutch and brake at each gear stage are shown in Table 1.

Next, the hydraulic circuit for the coasting clutch 12 will be explained with reference to FIG. 2.

In FIG. 3, reference numeral 24 denotes a pressure regulating valve 25 that regulates the oil pressure from the oil pump 22 to generate line pressure.
is a manual valve that is linked to a select lever (not shown) that is manually operated by the driver.

The pressure regulating valve 24 has a spool 24a and a spring 24b that biases the spool 24a to the right in the figure with a biasing force Q, and the oil pump is attached to both ends of the spool 24a. Hydraulic pressure P' supplied from 22
and an oil chamber 2 into which control pressure Q for line pressure adjustment is introduced.
4c and 24d are provided, respectively. Then, the spool 24a is minutely moved left and right depending on the magnitude relationship between the total pressure P of the biasing force Q1 and the control pressure Q (that is, the target line pressure) and the oil pressure P' from the oil pump 22, and the oil pump The hydraulic pressure P' can be adjusted to the target line pressure P by adjusting the communication/blocking between the line pressure passage 26 leading from the manual valve 22 to the manual valve 25 and the drain passage 28 leading to the oil tank 27.

The configuration for generating the control pressure Q is connected to one oil chamber 24d of the pressure regulating valve 24 via an oil passage 29, and is configured to generate the discharge pressure P' from the oil pump 22.
a pressure reducing valve 30 that reduces the pressure and acts on the oil passage 29;
and a duty electromagnetic valve 31 connected in the middle of the oil passage 29. By adjusting the opening ratio of the oil passage 29 to the oil tank 27 side by the ON-OFF operation of the duty solenoid valve 31, the control pressure Q is adjusted in magnitude, and by this adjustment, the line pressure P is adjusted in magnitude. Adjustments are being made. The operation of this duty solenoid valve 31 is controlled by a control unit 33 that functions as a hydraulic control device, as will be described later.

□ On the other hand, the manual valve 25 is slidably inserted into the valve body 25a and has a select lever (
(not shown).

Select lever is D (automatic shift up to 4th forward speed), S
(automatic shifting up to 3rd forward speed) and L (automatic shifting up to 2nd forward speed) when positioned in the forward driving range position, and when positioned in the R (reverse) range position,
When positioned in the P (parking) range position and in the N (neutral) range position, the spool 25b also moves in conjunction with the valve body 25a to move to the DlS, L travel positions, and the R position. , P position and N position, respectively.

Further, the manual valve 25 is supplied with the line pressure regulated by the pressure regulating valve 24 through a line pressure passage 26, and the spool 25b, S, and L are moved forward. When the spool 25b is in the N position, the line pressure passage 26 is communicated with the line pressure passage 34 on the downstream side of the manual valve 25, while when the spool 25b is in the N position, the line pressure passage 26 is communicated with the line pressure passage 34 on the downstream side of the manual valve 25.
6 is shut off, and the line pressure passage 34 on the downstream side of the manual valve 25 is communicated with the oil tank 27 via the tank passage 35.

The line pressure passage 34 on the downstream side of the manual valve 25 is connected in communication with the coasting clutch 12 of the transmission gear device 3, and a coasting clutch valve 36 and a coasting control valve 37 are provided along the way. Also interposed is a check pulp 38 with a squeezer which acts as a delay means. The coasting clutch valve 36 operates to open the coasting clutch 12 when the gears are in the first forward speed and the fourth forward speed (OD) in the D range position. Spool 3 due to 0N-OFF operation of
Change the position of 6a to move forward to the second position where the engine brake is effective.
and 3rd gear (i.e., when the solenoid valve 3
9), the spool 36a is positioned at the illustrated position by the biasing force of the spring 36b, and the line pressure passage 34 is communicated with the coasting clutch! On the other hand, when achieving the first and fourth forward gears where the engine brake is not effective (that is, when the solenoid valve 39 is turned OFF), the spool 36a is closed by the action of hydraulic pressure. By moving it to the left in the figure, the line pressure passage 34 is brought into communication with the oil tank 27 side, and the coasting clutch 12 is opened. Further, the coasting control valve 37 controls the coasting clutch 1 during the first forward speed and the fourth forward speed.
This acts to ensure that the oil pressure of No. 2 is released to the oil tank 27. Furthermore, the above-mentioned check valve 3 with a restriction
8 is when shifting to forward second speed and third speed (i.e., forward clutch 10 and coasting clutch 12
2), the line pressure is supplied to the coasting clutch 12 via the throttle 38a, and the engagement of the coasting clutch 12 is delayed by that amount from the engagement of the forward clutch 10. In other words, the throttle check valve 38 functions as a delay means for delaying the engagement of the coasting clutch 12.

Now, the duty solenoid valve 3 of the line pressure adjusting means 32
As mentioned above, the operation is controlled by the control unit 33 which has a built-in CPU, etc., and the control unit 33 includes an inhibitor switch 40 that detects the range position of the select lever and an accelerator that detects the range position of the select lever. Detection signals from a throttle sensor 41 that detects a pedal operation state and a vehicle speed sensor 42 that detects vehicle speed are respectively input.

The control unit 33 controls the inhibitor switch 40 as shown in the functional correspondence diagram shown in FIG.
a shift operation determination means for determining whether the transmission gear device 3 has been operated to switch to a gear position in which engine braking is effective (i.e., a forward second gear and a third forward gear) in response to a range position signal K from the an accelerator pedal operation determining means for determining whether or not the accelerator pedal is in the open state based on the throttle valve opening signal θ from the throttle sensor 41; A line pressure control means for controlling the line pressure adjustment means 32 to temporarily increase the line pressure P for engaging the coasting clutch 12 during operation, and a time T for increasing the line pressure P by the line pressure control means based on the vehicle speed. A correction means for correcting according to the vehicle speed signal V from the sensor 42 is provided.

Next, the operation control of the duty electromagnetic valve 31 by the control unit 33 will be described in detail with reference to the flowchart shown in FIG.

First, inhibitor switch 40, throttle sensor 4
When the 1 throttle valve opening signal θ and the vehicle speed signal V are respectively input to the range position signals from the 1 and vehicle speed sensors 42 (step S), the gear position where engine braking is effective is selected based on the range position signal K (i.e., When the shift operation determining means determines whether or not the gears have been shifted to the second and third gears (step St)
Based on the throttle valve opening signal 0, the accelerator pedal operation determining means determines whether or not the vehicle is running under engine braking, in which the valve opening θ changes in the direction of decreasing walking speed (that is, dθ/dt<0). Step S,). Then, only when an affirmative determination is made in steps S and S, the operation is controlled as follows in order to hasten the engagement operation of the coasting clutch 12.

That is, in order to temporarily increase the line pressure P6 at that time, the line pressure is calculated by P=P, +α (step S), and the pressure increase time T corresponding to the vehicle speed V at that time is determined in advance. It is read from the stored map (see FIG. 5) (step S). In the calculation in step S4, the pressurized dust α is given as a set value.

Here, the pressure increase time T is controlled in correspondence with the vehicle speed V using a map that expresses the line pressure increase time t as a function of the vehicle speed ■. This is to cope with the increase.

Thereafter, in order to obtain the control pressure Q of the pressure regulating valve 24 in accordance with the target line pressure P determined in step S4, the duty electromagnetic valve 3I is operated and controlled as described above (step S), The line pressure is increased until a timer (incorporated in the control unit 33) that is activated based on the pressure increase time T determined in step S5 counts up, and after waiting for the timer to count up (steps S7 and SS), the line pressure is regulated to the normal value P0 without the pressure increase (step S).

Note that if negative determinations are made in steps S and S3, the line pressure control means in the control unit 33 is not operated, and the course clutch 12 is engaged by normal pressure regulation control. In other words, the coasting clutch 12 is engaged later than the forward clutch IO due to the action of the check valve 38 with throttle.

As described above, according to this embodiment, when switching to the second forward speed and the third forward speed in each of the D, S, and L range positions, the forward clutch lO and the coasting clutch 12 are both engaged ( (See Table 1 above), the supply of line pressure to the coasting clutch 12 will be delayed due to the presence of the check valve 38 with throttle, and the coasting clutch 12 will be engaged later than the forward clutch IO. , a good gear shift is performed without any shift shock. At this time, the select lever is not operated and it is not the time to change to a gear position where engine braking is effective.
Since the line pressure control means does not control the duty solenoid valve 31, the line pressure is at the normal value P.
G is held and coasting clutch 1
2. The delay in conclusion is ensured.

On the other hand, when the driver consciously requests a large engine brake, the driver should change the range position of the select lever, such as D.
-S or D-4-L to actively shift to a gear position where engine braking is effective, and at the same time open the accelerator pedal to operate the throttle valve opening in the closing direction. As a result, the duty electromagnetic valve 31 is controlled by the line pressure control means and correction means of the control unit 33. That is, the line pressure is raised to a high level for a time T corresponding to the vehicle speed V,
Regardless of the presence of the check valve 38 with throttle, the line pressure is immediately supplied to the coasting clutch 12, and the coasting clutch 2 is quickly engaged. Therefore, the engine brake is effectively applied according to the driver's intention, and the driver does not feel a feeling of idle running.

Moreover, since the line pressure increase time T is controlled in accordance with the vehicle speed V, it is possible to perform optimal line pressure control corresponding to the engine brake torque when the engine brake is activated. In addition, since the coasting clutch 12 is quickly engaged by increasing the line pressure, there is no need to provide multiple line pressure passages or a device for switching between them, and the circuit configuration can be easily changed. can.

In the above embodiment, the engine brake request is detected by detecting a change in the range position of the select lever to the low speed side, but when the hold switch is pressed down (from 4th forward speed to 3rd speed) This may be done by detecting when a downshift to a higher speed is requested.

(Effects of the Invention) As described above, according to the present invention, there is provided a coasting clutch that operates to achieve a gear position where engine braking is effective, a transmission mechanism that switches a power transmission path to a plurality of stages, and a coasting clutch that operates to achieve a gear position where engine braking is effective. In an automatic transmission equipped with a delay means that delays the supply of line pressure to the coasting clutch upon engagement, the driver consciously requests a large engine braking action. When the range position is selected to the low speed side by operating the select lever and the accelerator pedal is released, the line pressure is increased by the action of the line pressure control means and correction means for a predetermined time corresponding to the vehicle speed at that time. As a result, line pressure is immediately supplied to the coasting clutch regardless of the intervention of the delay means, which effectively prevents response delays when engine braking is requested, effectively reducing the feeling of dry running felt by drivers. It has the excellent effect of reducing the

In addition, since the line pressure increase time when an engine brake is requested is controlled in accordance with the vehicle speed at that time, it is possible to perform optimal line pressure control corresponding to the engine brake torque when an engine brake is requested, and the speed change Another effect is that shock can be suppressed as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a functional correspondence diagram showing the configuration of a hydraulic control device for an automatic transmission according to the present invention, FIG. 2 is an overall configuration diagram of an automatic transmission according to an embodiment of the present invention, and FIG. A hydraulic circuit diagram for a coasting clutch in an automatic transmission, FIG. 4 is a flowchart for explaining the operation of the hydraulic control device for an automatic transmission according to an embodiment of the present invention, and FIG. This is a map showing the relationship between vehicle speed and line pressure increase time used in the explanation of the operation of the hydraulic control device for such an automatic transmission. 3...Transmission mechanism 12...Coasting clutch 32...
・・Line pressure adjustment means 33φ・・・Control unit 38・・・・
・Delay means

Claims (1)

[Claims] 1. A coasting clutch that operates to achieve a gear position where engine braking is effective, a transmission mechanism that switches a power transmission path to multiple stages, and a line pressure supply to the coasting clutch when the coasting clutch is engaged. A hydraulic control device for an automatic transmission, comprising a delay means that acts to delay the engagement of the automatic transmission,
A line pressure adjustment means for adjusting the line pressure, a shift operation determination means for determining whether the transmission mechanism has been switched to a gear position where engine braking is effective, and a shift operation determination means for determining whether the accelerator pedal is in an open state. The accelerator pedal operation determination means and the line pressure adjustment means are controlled to temporarily increase the line pressure for engaging the coasting clutch when the accelerator pedal is released when switching to a gear position where engine braking is effective. 1. A hydraulic control device for an automatic transmission, comprising a line pressure control means and a correction means for correcting the line pressure increase time by the line pressure control means in accordance with vehicle speed.