JPH0330012B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates primarily to a hydraulic pressure control device for controlling a hydraulic clutch for a power shift type transmission of a vehicle.

In this type of conventional device, for example, as shown in FIG. 1, a directional control valve 3 that receives pressurized fluid from a pump 2 whose pressure is limited by a pressure control mechanism 1 is installed in a plurality of gear trains of a transmission. Among the hydraulic clutches 4, 5, and 6, for example, pump pressure fluid is introduced to the clutch cylinder 7 of the clutch 4 of the clutch-off state, and the clutch cylinder 8 of the clutch 6 of the clutch-on state is communicated with the tank 9. As a result, the clutch 4 is turned on by the pressure fluid filled in the clutch cylinder 7, and the clutch 6 is turned off as the pressure in the clutch cylinder 8 decreases as shown by the broken line in FIG.

The pressure control mechanism 1 is comprised of a relief valve 10, a cylinder 12 for adjusting the spring force of a spring 11 that determines its set pressure, and an orifice 13 with a check valve, and operates as follows.

When an empty clutch cylinder, for example, the clutch cylinder 7, is filled with pressure fluid, the supply fluid pressure becomes a low pressure corresponding to the pressure fluid filling resistance to the clutch cylinder 7, so the pressure fluid in the head chamber 14 of the cylinder 12 is Pressed by the springs 15, 11, the air passes through the check valve 16 and is discharged to the flow path 17, and the set pressure of the relief valve 10 is lowered by the expanded springs 15, 11. When the clutch cylinder 7 is filled with pressure fluid, the clutch 4 starts to engage as shown in FIG. Through the torque converter 19, cooler 20, lubricant distributor 2
1 and then refluxed to tank 9. Therefore, the supply liquid pressure becomes the pressure set by the relief valve 10, but at the same time, a part of the pressure liquid passes through the throttle 18 and enters the head chamber 1.
4 and compresses the spring 11, the set pressure of the relief valve 10 gradually increases. As a result, the supply fluid pressure rises and continues to rise even after the clutch 4 is connected, and when the head chamber 14 reaches its maximum capacity, the flow of pressure fluid into the head chamber 14 is stopped and the relief valve 10 reaches its maximum set pressure. Note that 22 is a low pressure relief valve that limits the inflow pressure to the torque converter 19.

The conventional device as described above has the following drawbacks.

(a) There is a large loss in pump drive power.

During vehicle operation, the relief valve 10 is a directional switching valve 3.
The pressure fluid from the pump 2 is set at the highest pressure in order to maintain the clutch pressing force except during gear shifting, and the pressure fluid from the pump 2 is supplied to the torque converter 19 at a very low pressure from the relief valve 10, except for the amount to replenish leakage from the clutch cylinder etc. , the cooler 20 and the lubricant distributor 21 before being returned to the tank 9.
Therefore, most of the pressure fluid energy from the pump 2 is wasted except during speed change, and the pump 2 wastes power. Generally, the pump is driven by the same engine that drives the power transmission, so
If the power loss of the pump is large, the power transmission efficiency of the transmission is reduced, which is equivalent to a decrease in the fuel efficiency of the vehicle.

(b) It takes a long time to fill the clutch cylinder pressure fluid during gear shifting.

During the clutch cylinder pressure fluid filling during gear shifting, the supply fluid pressure is reduced as described above and all clutch connecting forces are reduced, so the transmission cannot transmit power.
If the idling time of the power is long, the shift becomes redundant, and the vehicle speed decreases or the vehicle stops on an uphill slope, making it impossible to obtain a smooth shift. Therefore, if the pump discharge amount is increased in order to shorten the idling time of the power by accelerating the filling speed of the pressure fluid into the clutch cylinder, the pump driving power increases and the above-mentioned decrease in fuel efficiency becomes even more significant.

It is an object of the present invention to provide a hydraulic clutch cylinder control device that greatly reduces pump power loss by driving the pump at as low a pressure as possible, and also shortens the time for filling the clutch cylinder with pressure fluid to quickly change gears. It is an object.

In order to achieve the above object, the hydraulic clutch cylinder control device according to the present invention includes a pressure control mechanism interposed between the pump and a directional control valve that selectively connects a plurality of clutch cylinders to the pump and the tank. In the hydraulic clutch cylinder control device, the pressure control mechanism uses a relief valve and a set pressure of the relief valve to specify the setting pressure of the relief valve between the clutch cylinder pressure fluid filling pressure at the time of fluid filling and the clutch connection start pressure. means for setting the pressure to a specified pressure after the start of clutch engagement; a check valve located between the relief valve and the directional control valve that allows fluid to flow only toward the directional control valve side; An unload valve is provided that unloads the control fluid pressure when a predetermined pressure lower than the specified pressure is exceeded, and an accumulator is disposed between the check valve and the directional control valve.

The present invention will be specifically described below based on embodiments shown in the drawings. In FIG. 3, the directional control valve 3 is connected to the clutch cylinders 7, 3 of the hydraulic clutches 4, 5, 6.
3 and 8 are selectively connected to the pump 2 and the tank 9, and the excess liquid is discharged through the relief valve 10 of the pressure control mechanism 25.
The liquid is then returned to the tank 9 via the torque converter 19, cooler 20, and lubricant distributor 21. The pressure control mechanism 25 includes a relief valve 10, a cylinder 12 that abuts a piston rod 23 pressed down by a spring 15 against a spring 11 that determines its set pressure, and a relief branched from the head chamber 14 of this cylinder and the pump flow path 17. A restrictor 13 with a check valve for regulating the flow of control pressure liquid into and out of the head chamber 14 is interposed in a passage 27 that connects with the valve primary side passage 26.

The above configuration is the same as the conventional device shown in FIG.

In this embodiment, the pressure control mechanism 25 includes:
Furthermore, a check valve 28 allows fluid to flow only downstream from the connection point of the flow path 26 of the flow path 17 toward the directional control valve 3 side.
Also, an unload valve 29 is provided upstream of this check valve, in which a pilot passage 34 is connected downstream of the check valve 28, and its secondary port is connected to the relief valve 10 and the torque converter 19 by a flow path 30. It is connected to a flow path 31 that connects the two.

On the other hand, an accumulator 32 is disposed between the check valve 28 and the directional control valve 3, and the pressure fluid accumulation capacity thereof is smaller than the pressure fluid filling capacity of the clutch cylinder.

Since this embodiment has the above-described configuration, for example, the clutch cylinders 7 of the hydraulic clutches 4, 5,
33 is in communication with the tank 9 and the clutch cylinder 8 of the hydraulic clutch 6 is in communication with the pump 2, the directional control valve 3 is switched to connect the clutch cylinder 7 of the hydraulic clutch 4 to the pump 2, and the hydraulic clutch is connected to the pump 2. When the clutch cylinder 8 of No. 6 is connected to the tank 9, the hydraulic clutch 6 is declutched off, and the previously empty clutch cylinder 7 is filled with pressure fluid from the pump 2 and the accumulator 32, so it is quickly filled with pressure fluid. .

Since the supply of pressurized fluid from the accumulator 32 to the clutch cylinder 7 is exhausted before the filling of the clutch cylinder 7 is completed, the hydraulic pressure will not suddenly increase due to the pressurized fluid accumulated in the accumulator 32 when the filling of the clutch cylinder 7 with the pressurized fluid is completed. do not have. The hydraulic pressure when the clutch cylinder 7 pressure fluid is filled is limited by the relief valve 10 which is set to a specified pressure (minimum set pressure) between the pressure fluid filling pressure and the clutch connection start pressure. The pressure will be low depending on the liquid filling resistance.

When the clutch cylinder 7 is filled with pressure fluid, the clutch is engaged, and the amount of pressure fluid supplied to the clutch cylinder from the start of clutch engagement to the completion of clutch engagement (hereinafter referred to as "clutch engagement") is only a small amount; The oil is returned to the tank 9 via the relief valve 10, the torque converter 19, the cooler 20, and the lubricating liquid distributor 21, but a portion is diverted to the accumulator 32 and the head chamber 14 of the cylinder 12, where the pressure liquid is accumulated. At the same time, the relief valve 10 compresses the spring 11.
The set pressure of is gradually increased. When the clutch is connected, the unload valve 29 is closed because the hydraulic pressure supplied to the clutch cylinder 7 is low. Clutch connection is completed,
When the supply liquid pressure further increases and exceeds the set pressure (predetermined pressure) of the unload valve 29, the unload valve 29, which receives that pressure via the pilot passage 34, opens, and the pressure liquid from the pump 2 is sent to the tank. miss
That is, the pump pressure liquid passes through the unload valve 29, passes through the low-pressure torque converter 19, the cooler 20, and the lubricating liquid distributor 21, and returns to the tank 9. Therefore, the pressure liquid in the head chamber 14 is pushed by the springs 15 and 11 and is discharged from the check valve 16 to the flow path 26.
The set pressure of the relief valve 10 is reduced by the expansion of the spring 11 to a level close to the pressure fluid filling pressure when the clutch cylinder pressure fluid is filled. On the other hand, the hydraulic pressure connecting the clutch 4 is disconnected from the pump side by the check valve 28, and is maintained by the operating pressure of the accumulator 32. Therefore, the pump hydraulic pressure upstream from the check valve 28 is low, and the pump driving power is small.

However, the storage capacity of the accumulator 32 decreases due to leakage from the clutch cylinder, etc.
When the pressure downstream of the check valve falls below the set pressure of the unload valve 29, the unload valve 29 closes, the pump hydraulic pressure compresses the spring 11, and the set pressure of the relief valve 10 increases. As a result, the upstream pressure of the check valve 28 becomes higher than the downstream pressure, and the check valve 2
8 opens, the accumulator 32 re-accumulates the pressure fluid, and when the fluid pressure exceeds the set pressure of the unload valve 29, the unload valve 29 opens again and unloads the pressure fluid from the pump 2. The set pressure of valve 10 decreases and check valve 28 closes.

To explain the above fluid pressure changes with reference to Fig. 7,
The set pressure of the relief valve 10 is set slightly higher than the pressure fluid filling pressure when the clutch cylinder is filled with pressure fluid before the clutch is switched by the directional switching valve 3. Therefore, even if the clutch is switched by the directional control valve 3, the pump hydraulic pressure does not change much when the clutch cylinder pressure is filled with liquid. When the clutch connection is started, the pump hydraulic pressure gradually increases, and even after the clutch connection is completed, the pressure continues to increase, and when it exceeds the set pressure of the unload valve 29, the unload valve opens, and the pump hydraulic pressure decreases significantly.
On the other hand, the hydraulic pressure connecting the clutch gradually decreases due to leakage after the unload valve 29 is opened, as shown by the dashed line, and when it falls below the set pressure of the unload valve 29, the unload valve 29 closes, which causes the pump to pump again. As the hydraulic pressure increases and check valve 28 opens, the hydraulic pressure connecting the clutch increases and the accumulator re-accumulates. When the hydraulic pressure exceeds the set pressure of the unload valve 29, the unload valve opens and the check valve 28 closes, causing the pump hydraulic pressure to drop significantly.
It goes up and down as the door opens and closes. In this way, the pump hydraulic pressure is maintained at a low pressure except during the period from the start of clutch engagement to the opening of the unload valve when the clutch is engaged, and from the time of closing to the opening of the unload valve during accumulator re-accumulation.

Another embodiment shown in FIG.
An unload valve 35 connected downstream of the cylinder 12 is interposed in a return passage 37 branching from a passage 36 connecting the head chamber 14 of the cylinder 12 and the throttle 13 with a check valve and reaching the tank 9. The rest of the structure is the same as that of the embodiment shown in FIG.

In this embodiment, when the unload valve 35 opens, the pressure liquid in the head chamber 14 is discharged to the tank 9 through the unload valve 35, and the spring 11 is expanded to lower the set pressure of the relief valve 10. When the pump hydraulic pressure decreases and the unload valve 35 closes, the pump hydraulic pressure increases again and compresses the spring 11, so that the set pressure of the relief valve 10 increases. The other operations are the same as the embodiment shown in FIG. 3, and the hydraulic pressure changes as shown in FIG. 7.

In this embodiment, the unload valve 35 releases the pressure liquid in the head chamber 14 to the tank 9 during unloading.
It is smaller than the unload valve 29 shown in FIG. 3 which releases the pump discharge liquid to the tank 9.

In another embodiment shown in FIG. 5, the set pressure of the relief valve 10 of the pressure control mechanism 25 is adjusted by the load pressure of the control passage 38 communicating with the primary flow passage 26 of the relief valve 10 via the throttle 18. do. A return passage 40 connecting this control passage 38 to the tank 9
An unload valve 41 is provided which connects the pilot passage 34 downstream of the check valve 28, and this unload valve and an electromagnetic proportional relief valve 39 control the load pressure. The set pressure of the electromagnetic proportional relief valve 39 is controlled by an electric signal from an electric controller (not shown), and is set to a specified pressure (minimum set pressure) between the pressure fluid filling pressure when filling the clutch cylinder with pressure fluid and the clutch connection start pressure. ), and when the pressure fluid filling is completed, it gradually increases to the maximum set pressure (specified pressure).

The other configurations are the same as the embodiment shown in FIG.

In this embodiment, the hydraulic pressure supplied to the clutch cylinder is the set pressure (predetermined pressure) of the unload valve 41.
When the control passage 3 is exceeded, the unload valve 41 opens and the control passage 3
8 is communicated with the tank 9, so that the relief valve 10 is lowered to the lowest set pressure. In this case, the electromagnetic proportional relief valve 39 is set to the highest setting pressure by the electric controller, and the pressing force required for clutch connection is maintained by the operating pressure of the accumulator 32 when the check valve 28 is closed downstream of the check valve 28. ing. When the pressure downstream of the check valve 28 falls below the set pressure of the unload valve 41 due to leakage, etc., the unload valve closes, while the electromagnetic proportional relief valve 39 is set to the highest set pressure, so the flow path 26 is throttled 1.
The hydraulic pressure in the control passage 38 connected via the control passage 8 rises rapidly, and the set pressure of the relief valve 10 also rises rapidly. As a result, when the check valve 28 opens, the accumulator 3
2 performs re-accumulation, and when the pressure exceeds the set pressure of the unload valve 41, the unload valve opens again. Other operations are the same as the embodiment shown in FIG.

The hydraulic pressure changes in this example are as shown in Figure 8.
The pump fluid pressure becomes the pressure fluid filling pressure when the clutch cylinder pressure fluid is filled, and when the clutch connection starts, the pressure increases gradually, and even after the clutch connection is completed, the pressure continues to increase, and when it exceeds the set pressure of the unload valve, the unload valve 41
2, the check valve 28 is opened and the check valve 28 is closed. On the other hand, the hydraulic pressure in the clutch cylinder gradually decreases due to leakage after the unload valve 41 is opened, and when it falls below the set pressure of the unload valve, the unload valve closes and the set pressure of the relief valve 10 rapidly increases. As a result, the pump hydraulic pressure rises rapidly and the check valve 28 opens, causing the accumulator 32 to re-accumulate. When the hydraulic pressure exceeds the set pressure of the unload valve 41, the unload valve 41 opens and the pump hydraulic pressure drops significantly, and thereafter the pump hydraulic pressure rises and falls as the unload valve opens and closes.

In this way, in this embodiment, the electromagnetic proportional relief valve 3
The set pressure in the control passage 38 gradually increases after the filling of the pressurized liquid is completed and reaches the maximum set pressure, and when the unload valve is closed thereafter, the pressure in the control passage 38 rises rapidly. Compared to this, the time from closing to opening of the unload valve is significantly shorter. The rest is the same as in Figures 3 and 4, and the pump hydraulic pressure is low except for the period from the start of clutch engagement to the opening of the unload valve, and from the subsequent closing to opening of the unload valve. It is maintained.

Another embodiment shown in FIG. 6 includes a check valve 42 upstream of the accumulator 32 that only allows fluid flow to the accumulator, and an electromagnetic switching valve 43 downstream of the accumulator 32 in the hydraulic circuit shown in FIG. Further, the downstream side of the electromagnetic switching valve 43 and the upstream side of the check valve 42 are communicated by a bypass passage 44, and the other configuration is the same as that shown in FIG.

The electromagnetic switching valve 43 is closed by an electric signal from an electric controller (not shown) before the filling of pressure fluid into the clutch cylinder is completed, and is opened again when the supply pressure to the clutch cylinder has increased to a certain extent. ing. Therefore, even if the accumulated pressure fluid remains in the accumulator 32 when the clutch cylinder pressure fluid filling is completed, that pressure will not act on the clutch cylinder, so the fluid pressure will not suddenly increase when the pressure fluid filling is completed. do not have. Therefore, the storage capacity of the accumulator does not need to be limited to less than the filling capacity of the clutch cylinder and can be increased, so that the re-accumulation interval of pressurized fluid due to leakage can be lengthened. Other operations are the same as the embodiment shown in FIG.

Note that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the gist thereof.

As explained above, according to the present invention, the pump hydraulic pressure is controlled from the time when the clutch is engaged until the unload valve opens, and from when the unload valve closes to the opening when the pressure fluid is reaccumulated in the accumulator. Since the pressure is low, the pump driving torque is small, and the power loss for driving the pump can be significantly reduced. Furthermore, since the pressure fluid discharged from the accumulator is also added to the clutch cylinder to fill the clutch cylinder with the pressure fluid, the pressure fluid filling time is shortened and speeds can be changed quickly.

[Brief explanation of the drawing]

Figure 1 is a hydraulic circuit diagram of a conventional device, Figure 2 is a chart showing changes in pump hydraulic pressure and clutch cylinder hydraulic pressure in a conventional device, and Figures 3, 4, 5, and 6. 7 is a hydraulic pressure circuit diagram showing an embodiment of the present invention, FIG. 7 is a chart showing changes in hydraulic pressure in the embodiment shown in FIGS. 3 and 4, and FIG.
It is a chart showing changes in hydraulic pressure in the example shown in the figure. 2... Pump, 3... Directional switching valve, 7, 8, 33...
Clutch cylinder, 9... Tank, 10... Relief valve, 12... Cylinder, 25... Pressure control mechanism, 28
...Check valve, 29, 35, 41... Unload valve, 32... Accumulator, 39... Electromagnetic proportional relief valve.

Claims (1)

[Claims] 1. In a hydraulic clutch cylinder control device in which a pressure control mechanism is interposed between the pump and a directional valve that selectively connects a plurality of clutch cylinders to the pump and the tank, the pressure control mechanism includes a relief valve,
means for setting the set pressure of the relief valve to a specified pressure between the clutch cylinder pressure liquid filling pressure at the time of filling the clutch cylinder pressure liquid and the clutch connection start pressure via the control liquid pressure, and gradually increasing it to the specified pressure after the clutch connection start;
A check valve is located between the relief valve and the directional control valve and allows fluid to flow only toward the directional control valve, and when the downstream pressure of this check valve exceeds a predetermined pressure lower than the specified pressure, the control fluid pressure is unloaded. 1. A hydraulic clutch cylinder control device, comprising: an unloading valve for controlling the clutch, and an accumulator disposed between the check valve and the directional control valve.