JPS627014Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a hydraulic control device for controlling the hydraulic pressure applied to a hydraulic clutch in a hydraulic clutch type transmission device installed in a self-propelled agricultural vehicle, a construction vehicle, etc. A control piston that receives the tip of a hydraulic pressure setting spring and increases the strength of the oil pressure setting spring by advancing the control piston is provided so as to be able to move forward to a regulated position, and the control piston controls the hydraulic pressure of the oil supply circuit for the hydraulic clutch in the hydraulic clutch type transmission. The present invention relates to a hydraulic control device for a hydraulic clutch type transmission, which is provided with a pressure regulating valve mechanism configured to act through a throttle behind the hydraulic clutch type transmission.

A hydraulic control device configured as described above is known from, for example, Japanese Utility Model Application Publication No. 52-98051, etc., and operates a switching valve that switches and controls the supply and discharge of hydraulic pressure to and from a hydraulic clutch in a hydraulic clutch type transmission. When the control piston is displaced from one operating position to another operating position, the control piston is gradually advanced by the hydraulic action of the oil supply circuit via the above-mentioned throttle, and the strength of the pressure setting spring is increased. Since the hydraulic pressure is gradually increased, the hydraulic pressure applied to the hydraulic clutch is gradually increased, and the hydraulic clutch is smoothly engaged to smoothly start the vehicle or change the vehicle speed.

This invention attempts to solve the following problems in the hydraulic control device as described above. In other words, regulating the forward position of the control piston in the pressure regulating valve mechanism is achieved by forming an annular step on the inner peripheral surface of the valve case of the pressure regulating valve, and when the control piston moves forward until it comes into contact with this step. This is done by blocking the control piston from advancing at the step. By the way, when forming an annular stepped portion on the inner circumferential surface of the valve case of the pressure regulating valve in this way, the valve body of the pressure regulating valve and the control piston, which are respectively slidably provided within the same valve case, The control piston that is brought into contact with the stepped portion needs to have a larger diameter, and the control piston has a larger area for receiving hydraulic pressure than the valve body. When one of the hydraulic clutches is to be operated by displacing the switching valve from the neutral position to one of the working positions or from one working position to another working position, the piston for clutch actuation in the hydraulic clutch is moved. Until the friction plate and the mating plate are actuated and begin to be pushed, the hydraulic pressure applied to the hydraulic clutch remains approximately constant at a pressure corresponding to the spring force of the piston return spring in the clutch. Therefore, the initial relief pressure of the pressure regulating valve mechanism, that is, the relief pressure when the pressure regulating valve performs the relief operation with the control piston in its most retracted position, is set to a value near the oil pressure corresponding to the spring force of the piston return spring. If this is set, the pressure regulating valve will perform a relief operation when the clutch actuating piston starts pushing the friction plate and the mating plate, and a gradual increase in oil pressure from the above-mentioned initial relief pressure should be obtained, but in reality, At this point, the clutch application oil pressure is rapidly increased to a certain value, and a gradual increase in oil pressure from such value is obtained. This is because, as mentioned above, the hydraulic pressure receiving area of the control piston is larger than the hydraulic pressure receiving area of the valve body of the pressure regulating valve, so when the same hydraulic pressure acts on both, the control piston receives the pressure first. When the pressure regulating valve or its valve body performs the relief operation, the control piston has already been displaced forward by a small amount, and the pressure regulating valve is activated even with a relief pressure corresponding to the strength of the hydraulic pressure setting spring at that time. This is because this results in starting a relief operation. In this way, the clutch operating oil pressure is gradually increased not from an oil pressure corresponding to the strength of the oil pressure setting spring when the control piston is in its most retracted position, but from a higher oil pressure. The vehicle has poor starting or shifting feeling, especially in low gears. In other words, since the reduction ratio is large in low speed gears such as agricultural vehicles, the clutch operating hydraulic pressure is gradually increased from a relatively high pressure as described above, and when such a relatively high pressure rapidly acts on the hydraulic clutch, This is because the axle torque of the vehicle increases rapidly.

The configuration of the present hydraulic control device devised to solve the above-mentioned problems will be described with reference to the illustrated embodiment.

In Fig. 1, 1 indicates 3 stages in the forward direction of the vehicle;
In a hydraulic clutch type transmission that performs a one-speed shift in the reverse direction, it is a power shift shaft on which a plurality of (four in the illustrated case) free-rotating gears, all of which are not shown in Figure 1, are mounted. On the power shift shaft 1, there are four hydraulic clutches for selectively coupling each of the above-mentioned idle speed change gears to the power shift shaft 1, namely _F1 hydraulic clutch _2F1 , _F2 hydraulic clutch _2F2. , _F3 hydraulic clutch _2F3 and R hydraulic clutch 2R are provided. In order to supply hydraulic oil from the oil tank 3 to these hydraulic clutches _2F1-2R , a hydraulic pump 5 is inserted into the oil supply circuit 4 led from the oil tank 3 toward the hydraulic clutches _2F1-2R . In order to switch and control the supply and discharge of hydraulic oil to and from the hydraulic clutches _2F1-2R , the two ports on the primary side are connected to the oil supply circuit 4 and the oil tank 3, and the four ports on the secondary side are connected to the hydraulic clutch 2F. ₁ - 2R are provided with switching valves 6 connected to each other. The switching valve 6 has a neutral position N where the hydraulic fluid from the full hydraulic clutches 2F ₁ -2R is discharged and the full hydraulic clutches 2F ₁ -2R are disengaged, and a corresponding one hydraulic clutch 2F ₁ , 2F ₂ , 2F ₃ or 2R. 1st forward speed position F 1 , 2nd forward speed position F ₂ , and 3rd forward speed position for selectively engaging only the one hydraulic clutch 2F ₁ , 2F ₂ , 2F ₃ or 2R by supplying hydraulic oil to the hydraulic clutch 2F 1 , 2F ₂ , 2F 3 or 2R; F ₃ and reverse 1st speed position R.

When the above-mentioned switching valve 6 is placed in each operating position F ₁ , F ₂ , F ₃ or R, each hydraulic clutch 2F ₁ ,
In order to set the hydraulic pressure applied to 2F ₂ , 2F ₃ or 2R, a pressure regulating valve 7, also shown in FIG. 1, is provided. This pressure regulating valve 7 is inserted into a branch circuit 8 branched from the oil supply circuit 4 and led toward the oil tank 3, and the tip of the oil pressure setting spring 9 is regulated as will be explained later. The hydraulic unload valve 1 is received by a control piston 10 that can be advanced to the desired position, and is attached to the pressure regulating valve 7 in the illustrated case.
The hydraulic pressure on the primary side of the pressure regulating valve 7 is configured to act on the rear side of the control piston 10 through the throttle 12 in the pressure regulating valve 7 .

Similarly, as shown in FIG.
In particular, the branch circuit 8 is equipped with a relief valve 1 at the front stage of the branch circuit 8.
3 is in the inserted position, and this relief valve 13 is
It is said that the relief operation can be performed using the following hydraulic pressure.

That is, each of the above-mentioned hydraulic clutches 2F ₁ , 2
F ₂ , 2F ₃ , 2R are F ₁ hydraulic clutch 2F ₁ in Fig. 2
As shown in FIG. 1, a plurality of friction plates 16 and a mating plate 17 are slid onto the transmission gear 14 which is loosely fitted onto the power shift shaft 1 and the clutch housing 15 which is fixedly installed on the power shift shaft 1. A piston 19 is slidably supported in the clutch housing 15 and urged backward by a return spring 18, and hydraulic pressure is supplied to an oil chamber 20 behind the piston 19. The relief valve 13 is configured as a multi-plate type which is operated by pushing the friction plate 16 and the mating plate 17 forward and thereby causing them to frictionally engage with each other. A hydraulic pressure slightly higher than the hydraulic pressure corresponding to the spring force of the return spring 18 of the piston 19, specifically for example approximately
It is said that the relief operation is performed using a hydraulic pressure of 2.0 kg/cm ² . In addition, in Figure 2,
21 is a transmission shaft on the drive side of the hydraulic clutch type transmission;
Reference numeral 22 designates a speed change gear that is fixedly installed on the transmission shaft 21 and meshes with the speed change gear 14, and together with the speed change gear 14 constitutes a speed change gear train for the first forward speed.

A more specific structure of the pressure regulating valve 7 and the relief valve 13 will be explained with reference to FIGS. 3 and 4. In FIGS. 3 and 4, 23 is a plate body on which the hydraulic pump 5 is mounted. The relief valve 13, the pressure regulating valve 7, and the hydraulic unload valve 11 are arranged in series and connected to the plate body 23, as shown in the figure.
It is built into. Among these, the relief valve 13 is
A pump port 26 of the valve case 25 is opened to an oil passage 24 formed in the plate body 23 connected to the hydraulic pump 5, and a relief port of the valve case 25 is opened to another oil passage 27 in the plate body 23. 2
8 is opened, and a valve body 30 is provided inside the valve case 25 by being urged backward by a hydraulic pressure setting spring 29. It has a conventional structure in which the oil is operated through an oil passage hole 30a. Then, as shown by the chain line in FIG. 3, the valve body 30
The relief pressure of the relief valve 13, which relieves oil from the pump port 26 to the relief port 28 when the pump is moved forward, is controlled by the hydraulic pressure setting spring 2.
By appropriately setting the spring load of No. 9, the relief operation can be performed with a hydraulic pressure of about 2.0 kg/cm ² as described above.

Next, the pressure regulating valve 7 is provided with a valve body 33 and the control piston 10 facing each other in the valve case 32, and the oil pressure setting spring 9, which is composed of an inner and outer double compression coil spring, is attached to these. The control piston 10 is provided within the valve case 32 between the valve body 33 and the control piston 10. The pump port 34 is formed in the valve case 32 to open to the oil passage 27, and the relief port 35 is formed in the valve case 32 to open to another oil passage 36 in the plate body 23. . The valve body 33 is provided with an oil passage hole 33a for communicating the pump port 34 with an oil chamber 37 behind the valve body 33. In order to restrict the forward position of the control piston 10, an annular step 38 is formed on the inner circumferential surface of the valve case 32, and as shown in FIG. When the control piston 10 is advanced to this point, the forward movement of the control piston 10 is prevented, thereby restricting the forward position of the control piston 10. Therefore, as seen in FIGS. 3 and 4, the diameter or hydraulic pressure receiving area _S1 of the control piston 10 that slides in a range to the left of the stepped portion 38 is located to the right of such stepped portion 38. It is larger than the diameter of the valve body 33 or the hydraulic pressure receiving area _S2 . When the valve body 33 is advanced as shown by the chain line in FIG.
The pressure regulating valve 7, which relieves oil from the oil to the relief port 35, has its maximum oil pressure setting as the oil pressure setting when the control piston 10 takes the most forward position regulated by the stepped portion 38 as shown in FIG. A hydraulic pressure of approximately 17-18 kg/cm ² corresponding to the strength of the spring 9 is established on the primary side.
In FIGS. 3 and 4, reference numerals 39 and 40 are retaining rings that restrict the retreating positions of the valve body 33 and the control piston 10, respectively.

As described above, the hydraulic unload valve 11 attached to the pressure regulating valve 7 is configured as follows. In other words, this hydraulic unload valve 1
1, as shown in FIGS. 3 and 4, a valve body 42 is placed in a valve case 41 behind the control piston 10 of the pressure regulating valve 7, and a spring 44 is used to hold the valve body 42 in the most advanced position regulated by a retaining ring 43. It is configured to be movable and energized. Inside the valve body 42, which is hollow with both ends open,
A dense portion is provided at an intermediate position in the length direction, and the aperture 12 is formed in the dense portion. An annular groove 42a is formed in the outer peripheral surface of the valve body 42 at a midway position in the length direction, and an oil passage hole 42b that communicates the inside of the hollow part of the valve body 42 behind the throttle 12 with the annular groove 42a is formed in the outer peripheral surface of the valve body 42. It is provided on the body 42. In the valve case 41,
A pump port 45 that opens into the valve case 41 over a certain length in the length direction, and a valve body 42 that is normally open to the inside of the valve case 41.
A drain port 46 is formed which is blocked by the outer peripheral surface of the rear end, and when the valve body 42 is retreated as shown in FIG.
5 and 46 are designed to communicate with each other through an annular groove 42a on the outer peripheral surface of the valve body 42. Valve body 42
Furthermore, the oil passage hole 42c, which is blocked by the inner circumferential surface of the valve case 41 in the forward position shown in FIG. 3 and communicated with the pump port 45 in the retracted position shown in FIG. Both ends are opened in the hollow portion of the valve body 42 and on the outer peripheral surface of the valve body 42 . and pump port 4
5 communicates with the oil passage 27 which is connected to the relief port 28 of the relief valve 13 via an oil passage 47 formed in the plate body 23 similarly to the oil passage 27. Further, as shown in FIG. 1, a low pressure relief valve 48 is inserted into the branch circuit 8 and sets the lubricating oil pressure to approximately 0.2-0.5 kg/cm ² on the secondary side of the pressure regulating valve 7. The drain port 46 of the hydraulic unload valve 11 is opened to the oil passage 36 connected to the relief port 35 of the pressure regulating valve 7, and the oil passage 36 is located at the position shown in FIGS. The low pressure relief valve 48 provided in the plate body 23 is connected to the low pressure relief valve 48 by an oil passage 49 formed in the valve body 23 in the same way as the oil passage 36. 3rd, 4th
In the figure, 50 is an oil drain port from inside the spring 9 installation space in the pressure regulating valve 7.
This oil drain port 50 is also connected to the low pressure relief valve 48 through oil passages 36 and 49.

The illustrated hydraulic control device is constructed as explained above, and first, the functions of the pressure regulating valve 7 and the hydraulic unload valve 11 provided in the illustrated embodiment will be explained. It seems so. That is, in a state where no hydraulic pressure is established behind the control piston 10 of the pressure regulating valve 7, the valve body 42 of the hydraulic unload valve 11 is moved by the biasing force of the spring 44.
When hydraulic pressure is established on the primary side of the pressure regulating valve 7, the hydraulic pressure acting behind the valve body 42 through the pump port 45, the annular groove 42a and the oil passage hole 42b takes the forward position shown in FIG. 3. Therefore, the oil pressure setting by the pressure regulating valve 7 is such that the oil flowing from the pump port 45 of the hydraulic unload valve 11 into the hollow part of the valve body 42 behind the throttle 12 through the annular groove 42a and the oil passage hole 42b passes through the throttle 12. Since the hydraulic pressure is gradually introduced behind the control piston 10, the control piston 10 is gradually moved forward, and the strength of the oil pressure setting spring 9 is gradually increased.
This is done in such a manner that the oil pressure on the primary side of the pressure regulating valve 7 is gradually increased, and eventually the control piston 1
The oil pressure of about 17-18 kg/cm ² when the oil pressure is at the most advanced position regulated by the stepped portion 38 is established on the primary side of the pressure regulating valve 7. In this way, approximately 17-18 kg/cm ² is applied to the primary side of the pressure regulating valve 7.
If the hydraulic pressure is eliminated from the state where the hydraulic pressure is established, then the hydraulic pressure behind the valve body 42 of the hydraulic unload valve 11 is eliminated, and a high hydraulic pressure still exists behind the control piston 10. Therefore, the valve body 42 is moved back as shown in FIG. 4 by the hydraulic pressure behind the control piston 10 against the force of the spring 44. In this way, the valve body 42
As mentioned above, when the diaphragm 12
The inside of the hollow portion of the valve body 42 on the front side is communicated with the pump port 45 through the oil passage hole 42c, and
Since the pump port 45 is communicated with the drain port 46 by the annular groove 42b, hydraulic pressure is removed from behind the control piston 10 toward the drain port 46 of the hydraulic unload valve 11, thereby moving the pump to the forward position shown in FIG. The control piston 10 is immediately retracted by the force of the oil pressure setting spring 9 to the retracted position shown in FIG. After the control piston 10 has retreated in this manner, the valve body 42 of the hydraulic unload valve 11 is displaced to the forward position shown in FIG. 3 by the force of the spring 44 due to the release of the hydraulic pressure acting on its front side. It will be done. As a result of the above, the pressure regulating valve 7 and the hydraulic unload valve 11 attached thereto are quickly returned to the original neutral state.

That is, as shown in the circuit diagram in FIG. The port 46) is connected to the primary side of the low pressure relief valve 48 by the oil drain circuit 51, and in the normal position taken by the force of the spring 44 and the oil pressure on the primary side of the pressure regulating valve 7, the primary side of the pressure regulating valve 7 is throttled behind the control piston 10. 12 and the oil drain circuit 5
In the unloading position where one end is blocked and the piston 10 is displaced by the hydraulic pressure behind the control piston 10, the connection circuit 50' is connected to the oil drain circuit 51, and the hydraulic pressure is applied from behind the control piston 10 without going through the throttle 12. It is configured to be unloaded.

Next, the relief valve 13, which is a feature of this invention, is
The following effects can be obtained. That is, since the relief valve 13 is provided before the pressure regulating valve 7, it performs a relief operation prior to the pressure regulating valve 7. Therefore, when the switching valve 6 is displaced from the neutral position N to any operating position F ₁ , F ₂ , F ₃ or R, or from one operating position to another operating position, the hydraulic clutch 2F ₁ , 2F ₂ , 2F ₃ or 2R piston 19 is moved forward against the force of the return spring 18 and begins to push the friction plate 16 and the mating plate 17, that is, at the time when the relief valve 13 operates in relief, the oil supply circuit 4 The hydraulic pressure that is established and acts on the hydraulic clutches 2F ₁ , 2F ₂ , 2F ₃ or 2R or its piston 19 is applied to the relief valve 1
3. The pressure regulating valve 7 is operated only after the relief valve 13 performs a relief operation, but as mentioned above, the pressure receiving area S ₁ of the control piston 10 in the pressure regulating valve 7 is larger than the pressure receiving area S ₂ of the valve body 33. Even though the control piston 10 starts to displace before the valve body 33, the hydraulic clutches 2F ₁ , 2F ₂ , 2
Since the piston 19 of F ₃ or 2R has begun to push the friction plate 16 and the mating plate 17, the hydraulic pressure is gradually increased as expected by the advance of the control piston 10, and the oil pressure is gradually increased as described at the beginning. No inconvenience will occur.

To facilitate understanding of this point, the manner in which the clutch action oil pressure rises when the relief valve 13 is not provided and when it is provided is schematically illustrated in FIG. 5 and will be explained as follows. That is, in the conventional case where the relief valve 13 is not provided, as shown by a curve C' shown by a broken line, the operating time t ₁ of the piston 19 in the hydraulic clutch, that is, until the position where the piston 19 starts pushing the friction plate 16 and the mating plate 17 The control piston 10 is already moved forward during the time t ₁ until it is moved forward based on the fact that the pressure receiving area S ₁ of the control piston 10 is larger than the pressure receiving area S ₂ of the valve body 33; When the valve body 33 performs the relief operation after the above-mentioned time _t1 has elapsed, the control piston 10 has already been displaced forward by a small amount, and the hydraulic pressure P acting on the hydraulic clutch is a hydraulic pressure corresponding to the strength of the hydraulic pressure setting spring 9 at that time. The oil pressure P a corresponds to the strength of the oil pressure setting spring 9 when the control piston 10 advances to the position where it is regulated by the stepped portion 38 after being rapidly increased to P _{2 .}
A gradual increase in the clutch working oil pressure P is obtained.

On the other hand, according to this invention, the relief valve 13
When set, as shown by curve C shown in solid line,
During the actuation time _t1 of the piston 19, that is, while the relief valve 13 has not yet performed a relief operation, no hydraulic pressure is applied to the rear of the control piston 10 of the pressure regulating valve 7, and the piston 10 remains at the most retracted position. When the relief valve 13 performs the relief operation and the hydraulic pressure starts to act behind the control piston 10 after time _t1 has elapsed, the piston 19 of the hydraulic clutch has already begun to push the friction plate 16 and the mating plate 17. Even if the control piston 10 is moved forward more quickly than the valve body 33 based on the difference between the pressure receiving areas S ₁ and S ₂ , a gradual increase in the clutch action oil pressure P can be obtained from the relief pressure P ₁ of the relief valve 13. Become.

Therefore, in the conventional case according to the curve C' shown in FIG. 5, a relatively high hydraulic pressure _P2 is rapidly applied to the hydraulic clutch, resulting in an increase in axle torque, especially at low speeds of the vehicle. However, when the clutch action hydraulic pressure P is increased along the curve C shown in Fig. 5 according to this invention, it is necessary to increase the clutch hydraulic pressure P from a low hydraulic pressure _P1 . The oil pressure can be gradually increased, and the above-mentioned problems will not occur.

As described above, the hydraulic control device for a hydraulic clutch type transmission of this invention has a hydraulic pressure setting spring 9.
a control piston 10 that receives the tip of the control piston 10 and increases the strength of the oil pressure setting spring 9 by advancing the control piston 10;
Hydraulic clutches 2F ₁ , 2 in a hydraulic clutch type transmission are provided so as to be able to move forward to a regulated position.
F ₂ , 2F ₃ , and 2R are provided with a pressure regulating valve 7 mechanism configured so that the oil pressure of the oil supply circuit acts behind the control piston 10 through the throttle 12, and a pressure regulating valve 7 mechanism is provided at the front stage of the pressure regulating valve mechanism. Even in the configuration in which a relief valve 13 is provided which performs a relief operation with a hydraulic pressure slightly higher than the hydraulic pressure corresponding to the spring force of the piston return spring 18 in the hydraulic clutch, the relief valve 13 performs a relief operation and the control piston of the pressure regulating valve 7 Piston 19 in the hydraulic clutch at the time when hydraulic pressure is applied to 10
has already begun to push the friction plate 16 and the mating plate 17, and from this, the control piston 10 of the pressure regulating valve 7 is moved forward earlier than the valve body 33 based on the difference in the hydraulic pressure receiving area. This method also solves the problem mentioned at the beginning, since the clutch operating oil pressure is always gradually increased from a low oil pressure.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram showing an embodiment of this invention, Fig. 2 is a longitudinal cross-sectional view showing the specific structure of a hydraulic clutch whose working oil pressure is controlled by the same embodiment, and Fig. 3 is a hydraulic circuit diagram showing an embodiment of the invention.
4 and 4 are longitudinal cross-sectional views showing the concrete structure of the main part of the same embodiment in different states, respectively, and FIG. 5 is a schematic diagram showing the operation of the same embodiment in comparison with the operation of the conventional example. It is a graph. 1...Power shift shaft, 2F ₁ , 2F ₂ , 2F ₃ ,
2R... Hydraulic clutch, 4... Oil supply circuit, 5...
Hydraulic pump, 6...Switching valve, 7...Pressure regulating valve, 8...
... Branch circuit, 9 ... Oil pressure setting spring, 10
... Control piston, 11 ... Hydraulic unload valve, 12 ... Throttle, 13 ... Relief valve, 14 ...
...Speed gear, 15...Clutch housing, 16
...Friction plate, 17...Mating plate, 18...Return spring, 19...Piston, 25...Valve case,
26... Pump port, 28... Relief port, 30... Valve body, 32... Valve case, 33
...Valve body, 34...Pump port, 35...Relief port, 38...Step part, 42...Valve body, 44
...Spring, 45...Pump port, 46...
...Drain port.

Claims (1)

[Scope of utility model registration request] A control piston that receives the tip of a hydraulic pressure setting spring and increases the strength of the hydraulic pressure setting spring by advancing the control piston is provided so as to be able to move forward to a regulated position, and the hydraulic pressure of the oil supply circuit for the hydraulic clutch in the hydraulic clutch type transmission is controlled. A hydraulic control device comprising a pressure regulating valve mechanism configured to act behind a control piston through a throttle,
A relief valve for a hydraulic clutch type transmission, characterized in that a relief valve that performs a relief operation with a hydraulic pressure slightly higher than the hydraulic pressure corresponding to the spring force of the piston return spring in the hydraulic clutch is provided upstream of the pressure regulating valve mechanism. Hydraulic control device.