JPH05594Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention is a hydraulic control device for an automatic transmission of a vehicle, etc., and in particular, an automatic transmission that controls hydraulic pressure supplied to friction elements to reduce shift shock. This invention relates to a hydraulic control device.

(Conventional technology) In recent years, with the increasing number of automobiles equipped with automatic transmissions, in addition to the conventional ease of driving operation, there has been a demand for improvement in so-called driving feeling, as typified by reduction in shift shock. There is a tendency to In particular, since the load torque is large at the time of starting, the sudden connection between the load torque and the drive torque causes a large pitching operation in the vehicle body, causing discomfort to the driver.

As an example of a conventional hydraulic control device for an automatic transmission that aims to reduce the shift shock at the time of starting, there is one shown in FIG. 3, for example. In the figure, when a shift lever (not shown) is operated, high-pressure hydraulic oil is supplied to the pressure receiving chamber 3 of the accumulator 2 through the oil passage 1, and this oil pressure causes the piston 4 to resist the biasing force of the spring 5. and is pushed downward in FIG. 3. As a result, the working oil pressure in the oil passage 1 exhibits a change characteristic in which it gradually increases from approximately zero following the downward stroke of the piston 4, and returns to the supplied working oil pressure after a predetermined period of time. That is, a friction element (not shown) is gradually engaged in accordance with the changing characteristics of the working oil pressure, thereby avoiding a sudden connection of load torque and reducing the shift shock at the time of starting.

By the way, in this conventional method, the speed at which the hydraulic pressure rises is slowed down to reduce the shift shock, which takes a long time to complete the shift, resulting in a so-called time lag, which causes discomfort to the driver. was giving. Further, since the above-mentioned change characteristic of the working oil pressure is determined by the spring constant of the spring 5, its control mode is extremely limited.

Therefore, the present applicant has previously proposed a hydraulic control device for an automatic transmission described in Japanese Patent Application No. 197465/1983. In this device, when the shift lever is operated, the hydraulic pressure supplied to the friction element gradually increases from approximately zero and changes, and after a predetermined time _t1 from the timing of the shift lever operation, the hydraulic oil flows into the orifice. is drained through. That is,
By draining the hydraulic oil, the engagement hydraulic pressure of the friction element can be temporarily reduced. Here, the dynamic friction coefficient μ of the friction element increases non-linearly as the friction element transitions from relative rotation to integral rotation, and records the maximum value just before reaching integral rotation, but the engagement hydraulic pressure is temporarily reduced. By reducing the dynamic friction coefficient μ, it is possible to suppress the increase in the dynamic friction coefficient μ, and as shown in FIG. This reduces the need for shifting shocks. Further, since the time lag is experienced by the above-mentioned predetermined time _t1 , by setting this to a desired value, the driving feeling can be improved and the range of control modes can be expanded.

(Problem to be solved by the invention) However, in the hydraulic control device for the automatic transmission of the prior application, the hydraulic pressure was controlled individually for each fastening element. For example, when two sets of friction elements operate at the same timing, such as when reversing, a hydraulic pressure control device is required for each friction element that operates, which raises the problem of increased costs. It was hot.

(Purpose of the invention) Therefore, the present invention focuses on the fact that when a plurality of friction elements are engaged, one friction element engages with a delay, and by controlling only the hydraulic pressure of the side where the engagement is delayed, The aim is to reduce shift shocks with a single control and improve driving feel.

(Means for Solving the Problems) In order to achieve the above-mentioned purpose, the hydraulic control device for an automatic transmission according to the present invention opens or closes an oil passage that supplies hydraulic pressure to a friction element that changes a gear shift state to a drain port. a control valve that opens and closes to open and close the control valve; and a control means that outputs a control signal to the control valve to open the control valve and temporarily lower the engagement hydraulic pressure during the engagement process of the friction element. In the hydraulic control device for an automatic transmission, the control valve is provided in the oil passage of the friction element that is the last to be engaged among the plurality of friction elements that engage in one gear shift state. .

(Operation) In the present invention, the hydraulic pressure of the friction engagement mechanism on the side where engagement is delayed among the plurality of friction engagement mechanisms is temporarily controlled to be reduced. Therefore, an excessive shift shock is avoided, and the occurrence of pitching motion of the vehicle body is effectively prevented.

(Example) Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a diagram showing a first embodiment of the hydraulic control device for an automatic transmission according to the present invention.
This is an example in which the present invention is applied to an automatic transmission having one gear stage and one reverse gear stage.

First, the configuration will be explained. In Figure 1, 11
is an oil road. The oil passage 11 is connected on one side 11a to an output port of a manual valve that operates in conjunction with a shift lever (not shown), and on the other side 11a.
b is connected to a predetermined friction element (not shown). This friction element acts on a gear transmission mechanism (not shown) to set the gear to a predetermined gear (for example, reverse), and in particular, the friction element acts on a gear transmission mechanism (not shown) to set the gear to a predetermined gear (for example, reverse). Of these, the friction elements that are the last to be engaged (for example, the low and reverse brakes and the low and reverse clutch that are engaged together during reverse gear shifting)
reverse brake). Further, the oil passage 11 communicates with a pressure receiving chamber 13 via an orifice 12, and the downstream side of the pressure receiving chamber 13 is closed by a valve body 14. The valve body 14 is connected to an actuator 15, and when the actuator 15 is energized under predetermined conditions, the valve body 14 opens to communicate the pressure receiving chamber 13 and the drain port 16. Actuator 1 above
5 and the valve body 14 function as a control valve that opens and closes the oil passage 11 to open or close it to the drain port 16. On the other hand, the inhibitor switch 17 detects the operation of the shift lever and outputs the detection signal Ss to the control circuit (control means) 18, and the control circuit 18 outputs the control signal Sa to the actuator at a predetermined control timing based on the detection signal Ss. Output to 15. Actuator 15
is energized to communicate the pressure receiving chamber 13 and the drain port 16 while the control signal Sa is being input, and thereby the drain port 16 communicates with the oil passage 11 via the orifice 12. The orifice 12, the pressure receiving chamber 13, the actuator 15, and the drain port 16 together constitute hydraulic control means.

Next, I will explain how it works.

Generally, the gear shifting operation of an automatic transmission is performed by selectively engaging a plurality of friction elements. For example, when reversing, two sets of friction elements, the low & reverse brake (hereinafter referred to as L&R/B) and the reverse clutch (hereinafter referred to as R/C), are engaged, which causes the rotation of the input shaft to reverse to the output shaft. and transmitted.

By the way, the torque applied to these friction elements varies depending on the gear ratio. For example, if the gear ratio during reverse is 2.5, the torque applied to L&R/B is approximately 3.5 of the torque applied to R/C. It will be doubled. On the other hand, in order to transmit power efficiently, it is desirable to set the transmission torque capacity ratio of R/C and L&R/B to correspond to the torque that is actually applied, but in reality, due to the limitations of unit dimensions,
The ratio is only about 1.5 to 2 times. As a result, the transmission torque capacity of the R/C near the input shaft has a margin and the engagement is completed early, but the L&R/B, which does not have a margin of transmission torque capacity, continues to slip during that time, and the friction coefficient μ reaches a predetermined value. The engagement is completed after reaching the value. Also, the driving torque at this time is L&R/B
The amount of torque transmitted by the engine is determined by the amount of torque transmitted by the engine, and the sudden torque fluctuation at the time of start (ie, shift shock) is also influenced by the engagement transient characteristics of the L&R/B.

Therefore, in order to reduce the shift shock without complicating the control system, it is sufficient to reduce the pressure of only the hydraulic pressure of the friction element (for example, L&R/B) on the side where the engagement is delayed.

In this embodiment, first, when the shift lever is operated from the non-driving range to the driving range (for example, reverse range), the oil passage 11 is opened from the manual valve (not shown).
High pressure hydraulic oil is supplied to the This hydraulic oil is supplied to a friction element (for example, L&R/
B) and flows into the pressure receiving chamber 13 via the orifice 12, making the working oil pressure approximately zero at the initial stage of supply. Further, as the amount of oil accumulated in the pressure receiving chamber 13 increases, the working oil pressure in the oil passage 11 gradually increases, and the friction elements (not shown) are gradually engaged.

On the other hand, the operation of the shift lever is detected by the inhibitor switch 17 and output as a detection signal Ss. After a predetermined timing is set in the control circuit 18, this detection signal Ss is output as a control signal.
It is output to the actuator 15 as Sa. The actuator 15 is energized while the control signal Sa is input to open the valve body 14 and open the pressure receiving chamber 13.
The hydraulic oil inside is drained out through the drain port 16. As a result, the hydraulic oil in the oil passage 11 is transferred to the orifice 12.
The hydraulic pressure in the oil passage 11 is reduced to a predetermined pressure determined by the orifice 12. Therefore, the engagement pressure of the friction element is reduced for a predetermined period of time, and torque fluctuations of the drive shaft are suppressed, and as a result, the shift shock at the time of starting is reduced.

FIG. 2 is a diagram showing a second embodiment of the hydraulic control device for an automatic transmission according to the present invention, and is an example in which the hydraulic pressure is controlled at one location to reduce shift shock during both forward movement and reverse movement. It is.

In Figure 2, shift the shift lever (not shown) from the non-driving range to the forward driving range (for example, D range).
When operated, high-pressure hydraulic oil flows into the oil passage 21 from a manual valve interlocked with the shift lever. This hydraulic oil is supplied to a friction element (for example, a low clutch) not shown through an oil passage 21, and is also supplied to a one-way valve 2 through an orifice 22.
3 is supplied to the inlet side. One way valve 23
allows flow in only one direction from the inlet side to the outlet side, so the hydraulic oil flows through the one-way valve 2.
3 and flows into the oil passage 24 and the oil passage 25. Further, the oil passage 25 is connected to a drain port 27 via an actuator 26, and the actuator 26 is energized upon receiving a predetermined control signal, thereby causing the oil passage 25 and the drain port 27 to communicate with each other. That is, by energizing the actuator 26 at a predetermined timing based on the operation of the shift lever,
The engagement hydraulic pressure of a predetermined friction element (for example, a low clutch) is reduced, and the shift shock during forward movement is alleviated.

On the other hand, when the shift lever is operated from the non-travel range to the reverse travel range, high-pressure hydraulic oil is supplied to the oil passage 28. This hydraulic oil is supplied to a friction element (for example, a low and reverse brake) not shown, and flows into the oil passage 31 and the oil passage 25 through the orifice 29, the one-way valve 30, and the oil passage 25. Furthermore, as in the case of forward movement, the actuator 26
When energized, the oil passage 25 and the drain port 27 communicate with each other, thereby reducing the engagement hydraulic pressure of a predetermined friction element (for example, low & reverse brake).
Shift shock when reversing is reduced. In addition, the above-mentioned orifice 22, oil passage 24, oil passage 25, actuator 26, drain port 27, orifice 29
The oil passage 31 constitutes a hydraulic control means. In this way, in this embodiment, a one-way valve is used to guide each hydraulic oil to the drain port, and the opening and closing of this drain port is controlled by a single actuator. It can also reduce the shift shock of your partner when backing up.

The orifice 22 and the orifice 29 have different orifice diameters, and these diameters are appropriately determined depending on the speed change shocks during forward movement and backward movement.

(Effects) According to the present invention, since the hydraulic pressure of the friction element that is delayed in engagement among the plurality of friction elements that engage in one shift state is controlled, the shift shock can be reduced at low cost. Driving feeling can be improved.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing the first embodiment of the present invention, Fig. 2 is a hydraulic system diagram showing the second embodiment of the invention, and Figs. 3 and 4 are hydraulic pressure of the automatic transmission of the earlier application. FIG. 3 is a diagram showing the main part of the accumulator, and FIG. 4 is a graph showing the characteristics of the output shaft torque. 11... Oil path, {14... Valve body, 15... Actuator} (control valve), 16... Drain port,
18... Control circuit (control means), 25... Oil path,
26... Actuator (control valve), 27... Drain port.

Claims (1)

[Claims for Utility Model Registration] A control valve that opens and closes an oil passage that supplies hydraulic pressure to a friction element that switches a speed change state to a drain port, and a control valve that operates to open and close an oil passage that supplies hydraulic pressure to a friction element that changes a speed change state; A hydraulic control device for an automatic transmission, comprising: a control means for outputting a control signal for opening the control valve and temporarily lowering the engagement hydraulic pressure during the engagement process of the automatic transmission; A hydraulic control device for an automatic transmission, characterized in that the control valve is provided in the oil passage of the friction element that is the last to complete engagement among the friction elements.