JPS628679Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a valve device disposed between a plurality of hydraulic clutches and a hydraulic pump, and is used when switching hydraulic pressure from one clutch (for example, a 1st speed clutch) to another clutch (2nd speed clutch). The purpose is to enable smooth engagement of the 2nd speed clutch without causing a shock.

Conventionally, in a switching valve that has a relief valve that works with one trimming plug and that switches continuously (there is no neutral position during switching), the newly engaged clutch (for example, a 2nd speed clutch) The slip time is shortened,
Shocks are likely to occur. The reason for this is that it takes time for the spring that sets the relief pressure and the trimming plug that supports the spring to return to the set base point (the point where the set oil pressure is the lowest), and the oil from the pump drains before the relief pressure has fallen sufficiently. This is because the oil pressure in the hydraulic chamber of the second speed clutch becomes high immediately after switching, and the time during which the clutch plate slips becomes extremely short.

In order to solve the above-mentioned conventional problems, this invention
The trimming plug hydraulic chamber is connected to the tank oil path via a check valve, and when the clutch is switched, the check valve opens and the hydraulic pressure in the trimming plug hydraulic chamber is released to the tank oil path, so that the trimming plug can be quickly removed when the clutch is switched. After returning to the initial position, the clutch oil pressure can be gradually increased from a low pressure over a sufficient period of time during the next connection operation. Specifically, it is constructed as follows.

That is, in the present invention, a switching mechanism for selectively connecting a pump oil passage of a hydraulic pump to a clutch oil passage of a plurality of clutches is provided in a switching valve disposed between a plurality of clutches and a hydraulic pump; A relief valve for setting and a trimming plug for moving the relief valve in the direction of increasing the set oil pressure in response to an increase in the clutch oil pressure are provided.

In the present invention, the trimming plug hydraulic chamber is connected to the pump oil path via the throttle and to the tank oil path via the check valve, and a first hydraulic chamber is provided for biasing the check valve in the closing direction. A second hydraulic chamber connected to the switching mechanism and for biasing the check valve in the opening direction is connected to the trimming valve hydraulic chamber, and when the switching mechanism has completed the switching operation, the first hydraulic chamber is pumped. The first hydraulic chamber is connected to the tank oil passage, and the first hydraulic chamber is connected to the tank oil passage in the middle of the switching operation.

Next, embodiments will be described with reference to the drawings.

In Figure 1, which is a hydraulic system diagram, the inlet of the hydraulic pump PM driven by the motor M is the oil tank.
TN, and the outlet is connected to a switching valve V via a pump oil line P. As will be explained in detail later, the outlet of the valve V is connected to the first gear clutch C ₁ , the second gear clutch C 2 , and the third gear clutch C 3 via clutch oil passages 1, ₂ , and ₃ , and also connects to the oil passage TN′. Connected to oil tank TN via. In addition, the pump oil passage P is connected to the lubricating oil passage via the relief valve R and the low pressure oil passage L.
Connected to L′ and tank TN. Furthermore, clutch
The structures of C ₁ , C ₂ , and C ₃ are the same as before.

In FIG. 2, which is a longitudinal sectional view, the switching valve V
Spool VS and relief valve R spool RS
are slidably fitted into the holes 5 and 6 of the valve housing 4, and the spools HS of the trimming plug T and check valve H are respectively fitted in the bottomed cylindrical cases 7 and 8 fixed in the holes of the housing 4. are slidably fitted.

The right end portion 9 of the switching valve spool VS in FIG.
(Fig. 1), and has lands 11 to 14 sandwiching small diameter parts 15 to 17 in order from the right end 9 side, and three detent balls 19 can be fitted to the left end. annular grooves 21, 22, 23
is formed. 25, 26, and 27 are annular passages formed around the small diameter portions 15, 16, and 17, respectively.

The relief valve spool RS has one end in contact with the compression coil springs 30 and 31, the other end facing the hydraulic chamber 32, and an annular groove 33 and a groove 3 on the outer peripheral surface.
3 to the spring 30 side, and an oil passage 36 connecting the groove 33 and the hydraulic chamber 32 inside.

The trimming plug T is opposed to the spool RS with springs 30 and 31 in between. In the initial state (minimum oil pressure state) shown in FIG. 2, the large diameter spring 30 is in pressure contact with the end face of the plug T, but the small diameter spring 31 is separated from the plug T by a distance b. The hole 6 has an annular stepped portion 3 on its inner circumferential surface at a distance a from the plug T.
It has 7. The inner edge of the stepped portion 37 protrudes radially inward from the opening edge of the case 7 (the left end in FIG. 2) to form a stopper for the plug T, and the distance a is, for example, about twice as large as the distance b. It is set large. The hole 6 has another annular step 39 on the inner peripheral surface near the spool RS, and the step 39
A compression coil spring 40 (return spring) is compressed between and the plug T. The end surface of the plug T opposite to the springs 30 and 31 faces the hydraulic chamber 41 (trimming chamber), and the hydraulic chamber 41 is connected to the oil passage 42.
It is connected to check valve H via.

A pump hydraulic chamber 43 and a tank oil passage 44 are formed on both sides of the spool HS of the check valve H. The end of the spool HS on the side of the tank oil passage 44 has a small diameter, and an annular hydraulic chamber 45 is formed around it, and the oil passage 42 is connected to the hydraulic chamber 45 .
The spool HS is provided with a throttle 46 that connects both hydraulic chambers 43 and 45. The part of the case 8 between the hydraulic chamber 45 and the oil passage 44 forms an annular valve seat 47, and in the initial state shown in FIG.
is seated.

The clutch oil passages 1, 2, 3, the pump oil passage P,
The low pressure oil passage L and the tank oil passage TN' are each connected to an annular groove (for example, 48) formed on the inner peripheral surface of the hole 5, and the specific position of each oil passage is as shown in Fig. The following settings are made for the spool VS at the connection location. The low-pressure tank oil passage TN′ at the right end in FIG. 2 is connected to the low-pressure oil passage 44, and
It is blocked off from the first speed clutch oil passage 1 by the land portion 11 . 1st speed clutch oil passage 1 is passage 25
It is connected to the pump oil path P via. The third-speed clutch oil passage 3, the adjacent tank oil passage TN′, and the second-speed clutch oil passage 2 communicate with each other via a passage 26, and are blocked from the pump oil passage P by the land portions 12 and 13. . The pump oil passage P adjacent to the land portion 13 is connected to the annular groove 33 via an internal oil passage 50, and further connected from the groove 33 to the hydraulic chamber 43 of the check valve H via an oil passage 50'. Second
The low-pressure oil passage L at the left end in the figure is blocked from the adjacent pump oil passage P by the land portion 14, and is connected to the annular groove 52 via the internal oil passage 51.
The annular groove 52 is formed on the inner peripheral surface of the hole 6 along the periphery of the spool RS, and in the initial state shown in FIG. 2, the throttle 35 occupies a position away from the groove 52 toward the hydraulic chamber 32 side. .

Explain the operation. In the initial state of 1st gear clutch connection shown in Fig. 2, hydraulic oil flows from the hydraulic pump PM through the pump oil path P, the passage 25, and the clutch oil path 1.
The oil flows into the hydraulic chamber of the speed clutch _C1 , and after a short time _t1 has elapsed from the initial state (minimum hydraulic pressure state: 0) as shown in Fig. 3, the hydraulic pressure rapidly reaches a relatively low value _P1 , and the hydraulic pressure of the clutch _C1 (the lowest Figure 2) begins to connect. Then, the hydraulic pressure of value P ₁ is introduced into the hydraulic chamber 32 through the pump oil passage P on the left side in FIG. 2, the oil passage 50, and the annular groove 33.
As shown in FIG. 4, the spool RS is pushed by the hydraulic pressure in the hydraulic chamber 32 and moves to a position where the throttle 35 communicates with the annular groove 52 with a large opening. Through this communication, a part of the pump hydraulic pressure is transferred to the annular groove 33, the throttle 35, and the annular groove 52.
After that, the oil begins to escape from the oil passage 51 to the low pressure oil passage L, and the oil pressure does not increase rapidly thereafter. On the other hand, a part of the hydraulic oil that has flowed into the annular groove 33 flows into the oil passage 50' and into the hydraulic chamber 4.
3. Since it flows into the hydraulic chamber 41 via the throttle 46 and the oil passage 42, the plug T gradually compresses the springs 30, 31, 40 under the pressure of the hydraulic pressure in the hydraulic chamber 41, and the spool RS compresses the springs 30, 31. The diaphragm 35 gradually moves in the direction of closing due to the elastic repulsion force. In this way, the opening degree of the diaphragm 35 gradually decreases, so
As shown in FIG. 3, after time _t1 has elapsed, the oil pressure gradually increases to the maximum value Pm while each part operates as described below.

In the above operation, from time t ₁ to time t ₃ , the plug T shown in FIG. 2 moves a distance b and compresses only one spring 30 of the two springs 30, 31, causing the relief valve to open. Spool RS has one spring 3
Since it is pushed only by 0, the rate of decrease in the opening of the throttle 35 is small, and the oil pressure gradually increases as shown in the period from time _t1 to time _t3 in FIG. After time _t3 , the spring 31 also begins to be compressed, and the repulsive force from the two springs 30 _and 31 moves the spool RS in the direction of closing the throttle ₃₅ . The oil pressure rises quickly.

In addition, as mentioned above, after the clutch C ₁ starts to connect at the predetermined oil pressure value P ₁ , the pressure contact force between the clutch plates gradually increases in response to the increase in oil pressure while slipping, and the pressure contact force between the clutch plates increases until the pressure reaches the predetermined value.
When P ₂ is reached, clutch C ₁ is fully engaged. The predetermined value P ₂ when fully connected changes depending on the clutch load. For example, when the clutch load is light, such as when there is no load, the predetermined value P ₂ becomes smaller than the predetermined value P ₃ , and the weight When the clutch load is heavy, such as when the clutch is loaded, the hydraulic pressure (P ₂ ) at full engagement becomes larger than the predetermined value P ₃ .

After the clutch C ₁ is completely connected in this way, when the spool _{VS shown} in _FIG . It works like. When the spool VS reaches the position where the detent ball 19 abuts the boundary between the grooves 21 and 22 during the switching operation as shown in FIG. The passage P is connected to the tank oil passage TN' through the passage 25, and when the oil pressure of the oil passage 1 and P is released, the clutch C ₁
is blocked. At the same time, the pump oil passage P on the left side in FIG. Hydraulic chamber 3
2 hydraulic pressure is also released, and the spool RS is spring 30,
31 returns to the initial position (the position where the volume of the hydraulic chamber 32 is at its minimum) and returns to a state where the next connection operation can be performed in the same manner as in the case of the first speed clutch _C1 . Furthermore, when the hydraulic pressure in the oil passage 50' is released, the hydraulic pressure in the hydraulic chamber 43 is also released, but in the state immediately after the start of switching (immediately before the state shown in FIG. 5), the spool HS is seated on the valve seat 47. Hydraulic chamber 4
1 and 45 communicate only with the hydraulic chamber 43 via the throttle 46, the hydraulic chamber 45 has a higher pressure than the hydraulic chamber 43. Therefore, the spool HS is pushed by the hydraulic pressure in the hydraulic chamber 45 and moves away from the valve seat 47 as shown in FIG. Then, the hydraulic chambers 41, 45 and the passage 42 communicate with the oil passage 44 through the wide gap between the spool RS and the valve seat 47, so the hydraulic pressure in the hydraulic chamber 41 is released, and the plug T is pushed by the springs 40, 30.
The hydraulic pressure chamber 41 also returns to its initial position (the position where the volume of the hydraulic chamber 41 is at its minimum), returning to a state where the next connection operation can be performed in the same manner as in the case of FIG. 1.

In this way, the relief valve R and the trimming plug T return to their initial positions during the switching operation, so that when the next clutch _C2 or _C3 is connected, the hydraulic pressure will change to the above-mentioned 1st speed as shown in the characteristic X' in Fig. 3. Kuratsuchi
As in the case of C ₁ (characteristic X), it gradually increases and the clutch C ₂ or C ₃ connects smoothly. Furthermore, the 6th
As shown in the figure, when the ball 19 is fitted into the groove 22 and the valve V is switched to the second speed clutch _C2 , the first speed clutch oil passage 1 is connected to the tank oil passage TN' via the passage 25, and the land portion 12 connects the pump oil. The second speed clutch oil passage 2 is connected to the pump oil passage P via a passage 27, and the land portion 1 is blocked from the passage P.
3, it is blocked from the tank oil path TN'. Also, the check valve spool HS is moved to a position where it is seated on the valve seat 47 by the hydraulic pressure introduced into the hydraulic chamber 43 immediately after switching.

As explained above, according to the present invention, since the check valve H is provided to quickly release the hydraulic pressure in the trimming plug hydraulic chamber 41 to the oil passage 44 when the clutch is switched as shown in FIG. 5, the trimming plug T can be quickly moved to the initial position. In the next connection operation, the clutch oil pressure can be gradually increased over a sufficient period of time, and the clutch can be smoothly connected.

To explain in more detail, the present invention includes a check valve H for connecting the trimming plug hydraulic chamber 41 to the tank oil passage 44 and TN', and a hydraulic chamber 43 for urging the check valve H in the closing direction.
(first hydraulic chamber) is connected to a switching mechanism (spool VS, etc.), and a hydraulic chamber 45 (second hydraulic chamber) for biasing the check valve in the opening direction is connected to the trimming valve hydraulic chamber 41. . The switching mechanism is configured to connect the hydraulic chamber 43 to the tank oil passage TN' only during the middle stroke of the switching operation (the state shown in FIG. 5). For this purpose, during the switching operation, the pressure in the hydraulic chamber 43 is sufficiently reduced and the check valve H is opened to ensure that the hydraulic pressure in the hydraulic chamber 41 of the trimming plug T is released to the tank oil passage TN', and the trimming plug T is immediately removed. can be returned to the initial state.

By the way, in conventional products that are not equipped with a check valve H, the hydraulic fluid in the hydraulic chamber 41 is discharged only through the throttle (the part corresponding to the throttle 46) during switching, so the hydraulic fluid in the hydraulic chamber 41 is completely discharged. Before that, ie before the plug T returns to its initial position, hydraulic pressure begins to be introduced into the new clutch (for example the second gear clutch C ₂ ). Therefore, the spool RS of the relief valve R is strongly pushed by the plug T via the spring 30 from the time the switching is completed (the start of hydraulic pressure introduction), and it moves only to the medium setting pressure state (the position where the throttle 35 is opened to a medium degree). Therefore _, as shown by the broken line
The pressure suddenly rises to high pressure (Pn) and a shock occurs when the clutch is engaged.

In addition, when embodying the present invention, the throttle 46 is provided in a portion other than the check valve H, and a branch passage communicating with the throttle is provided in the passage 50',
Pump hydraulic pressure can also be introduced into the trimming plug hydraulic chamber 41 without going through the hydraulic chamber 43. It is also possible to eliminate the spring 31. The invention can also be applied to systems with two clutches or more than four clutches.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic system diagram of the embodiment, Fig. 2 is a longitudinal sectional view of the valve device in the initial state of first clutch connection, Fig. 3 is a graph of hydraulic characteristics, and Fig. 4 is a state in which the first clutch is fully engaged. 5 is a longitudinal sectional view in the middle of switching, and FIG. 6 is a longitudinal sectional view in a state where the second clutch is fully connected. 41, 43, 45...Hydraulic chamber, 46...Aperture,
_C1 , _C2 , _C3 ...Hydraulic clutch, L...Low pressure oil line, H...Check valve, P...Pump oil line,
PM'...Hydraulic pump, R...Relief valve, T
...trimming plug, V...switching valve.

Claims (1)

[Scope of utility model registration request] A switching valve disposed between the plurality of clutches and the hydraulic pump includes a switching mechanism for selectively connecting the pump oil passage of the hydraulic pump to the clutch oil passage of the plurality of clutches, and a relief valve for setting the clutch oil pressure. and a trimming plug that moves the relief valve in the direction of increasing the set oil pressure in response to an increase in clutch oil pressure.The hydraulic chamber for the trimming plug is connected to the pump oil path via the throttle, and the tank oil is A first hydraulic chamber for biasing the check valve in the closing direction is connected to the switching mechanism, and a second hydraulic chamber for biasing the check valve in the opening direction is connected to the trimming valve hydraulic chamber. and the switching mechanism connects the first hydraulic chamber to the pump oil path in a state in which the switching operation is completed, and connects the first hydraulic chamber to the tank oil path during a stroke in the middle of the switching operation. A hydraulic clutch valve device characterized by: