JPS6225542Y2 - - 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. equipped with a pressure regulating valve configured to act through a throttle behind the
The present invention relates to a hydraulic control device for a 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.

By the way, as is well known, the viscosity of oil decreases relatively rapidly as the oil temperature rises, but when the viscosity of the hydraulic oil for the hydraulic clutch in a hydraulic clutch type transmission changes, the flow rate of the hydraulic oil passing through the above-mentioned throttle increases. The ratio will fluctuate. However, since hydraulic clutch type transmissions installed in agricultural vehicles etc. are operated continuously for relatively long periods of time, fluctuations or increases in the temperature of the hydraulic oil are relatively large, and the above-mentioned throttle passage flow rate ratio is low. There is a wide range of variation. For this reason, the hydraulic pressure applied to the hydraulic clutch cannot be gradually increased uniformly, and when the oil temperature is low, the rate of gradual increase in the hydraulic pressure applied to the clutch is low and the vehicle starts or accelerates relatively slowly.
A conventional problem has been that as the oil temperature rises, the rate of gradual increase in the clutch hydraulic pressure increases, causing the vehicle to start or accelerate relatively rapidly, which worsens the driver's feeling.

The purpose of this invention is to provide a hydraulic control system as mentioned above, so that the clutch action oil pressure can be gradually increased uniformly even if the temperature of the hydraulic oil fluctuates. Correct the problem,
In addition, this structure is used to remove hydraulic pressure from behind the control piston during gear shifting operations, and the control piston is reliably moved back to a position where the hydraulic pressure is gradually increased from a low hydraulic pressure. To provide a new hydraulic control device.

In order to solve this problem, this invention has a hydraulic pressure setting spring 10 as illustrated in the attached drawing.
a control piston 15 that receives the tip of the control piston 15 and increases the strength of the oil pressure setting spring 10 by advancing the control piston 15;
is provided so as to be able to move forward to a regulated position, and hydraulic clutches 2F ₁ ,
In a hydraulic control device equipped with a pressure regulating valve 7 configured so that the oil pressure of the oil supply circuit 4 for 2F ₂ , 2F ₃ , and 2R acts behind the control piston 15 through a throttle 38, the following technical features are implemented. Measures were taken.

That is, as similarly illustrated in the attached drawing, the oil passage 36 connecting the oil supply circuit 4 to the back of the control piston 15 is moved to a position where the oil passage 36 is variably throttled and the throttle action is released. A solenoid valve 30 with a flexible valve body 37 is provided, and the throttle 38 is constituted by the solenoid valve 30, and a temperature sensor 41 for sensing the temperature of the hydraulic oil and the hydraulic clutches 2F ₁ , 2F ₂ , 2F are provided. A sensor switch 45 is provided to detect the displacement operation of the switching valve 6 that switches and controls the supply and discharge of hydraulic oil to and from 3 and 2R _. In addition, the higher the temperature of the hydraulic oil sensed by the temperature sensor 41 is, the more the valve body 37 is moved to a position where the degree of constriction of the oil passage 36 is increased.
5 senses the switching valve displacement operation, the valve body 3
7 is inserted and installed so that it is once displaced to the throttle action release position.

Therefore, the hydraulic control device of this invention has a mechanism behind the control piston 15 that gradually advances by hydraulic action to gradually increase the clutch action oil pressure as described above.
Hydraulic pressure is applied through the orifice 38, which has a larger degree of restriction as the oil temperature rises, thereby suppressing an increase in the flow rate ratio passing through the orifice due to a decrease in oil viscosity due to an increase in oil temperature, and reducing the oil temperature. Even if the oil temperature fluctuates, the ratio of oil pressure supplied to the rear of the control piston 15, and therefore the ratio of gradual increase in the clutch action oil pressure, does not change, and the vehicle starts or accelerates at a constant level regardless of oil temperature fluctuations. , to improve the pilot's feeling.

Furthermore, in the past, in order to temporarily move the control piston back to a position where the oil pressure is gradually increased from a low oil pressure in conjunction with the speed change operation, a reverse movement is generally made that only allows oil to flow from behind the control piston 15 in the four directions of the oil supply circuit. A stop valve is provided, and when the switching valve 6 is operated to move between two positions, the oil supply circuit 4 is once connected to the oil tank, and the oil pressure on the secondary side of the check valve (oil supply circuit 4 side) is The hydraulic pressure was released from behind the control piston 15 by utilizing the fact that the check valve opens when the pressure decreases, but according to this method, if the switching valve 6 is quickly displaced, the hydraulic pressure is released. The opening operation of the responding check valve is delayed and the control piston 15
In some cases, the retraction of the aircraft was insufficient, and the oil pressure was gradually increased from a relatively high oil pressure, resulting in the pilot being shocked. In contrast, this invention uses a solenoid valve 30 that is linked to the operation of the switching valve 6 to release the restriction of the oil passage 36 and remove the oil pressure from behind the control piston 15, rather than using a check valve that responds to hydraulic pressure. By quickly opening the oil passage 36, the oil pressure can be quickly removed from behind the control piston 15, and the control piston 15 can be reliably retreated to a position where a gradual increase in oil pressure from a low oil pressure can be obtained. Become.

Examples will be described below.

In Fig. 1, 1 indicates 3 stages in the forward direction of the vehicle;
A power shift shaft on which a plurality of (four in the illustrated case) free-rotating transmission gears (not shown) are mounted in a hydraulic clutch type transmission that performs a one-speed shift in the reverse direction. are four hydraulic clutches for selectively coupling each of the above-mentioned idle speed change gears to the power shift shaft 1, that is, F ₁
Hydraulic clutches 2F ₁ , F ₂ , F ₃ hydraulic clutches 2F ₃ 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 2F ₁ -2R, and in order to switch and control the supply and discharge of hydraulic oil to the hydraulic clutches 2F ₁ -2R. , the 2 ports on the primary side are connected to the oil supply circuit 4 and the oil tank 3, and the 4 ports on the secondary side are connected to the hydraulic clutch 2F ₁ -2R.
A switching valve 6 is provided which is connected to each of the two. The switching valve 6 discharges the hydraulic oil from the full hydraulic clutch 2F ₁ -2R _.
neutral position N, where hydraulic oil is supplied to the corresponding one hydraulic clutch 2F ₁ , 2F ₂ , 2F ₃ or 2R, and hydraulic oil is discharged from the other three hydraulic clutches, and one hydraulic clutch 2F _{1,2F 2,2}
It has a forward first speed position F ₁ , a forward second speed position F ₂ , a forward third speed position F ₃ , and a reverse first speed position R in _which only F 3 or 2R is selectively engaged.

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 disposed in a valve housing 8 installed on a transmission case of an agricultural vehicle, etc., and inside the valve case 9 is a hydraulic A valve body 11 that is biased to move in the backward direction by a setting spring 10 is slidably provided. A pump port 12 and a relief port 13 are formed in the valve case 9 with an appropriate interval between them, and the valve body 11 has an annular groove 11a on the outer circumferential surface and an oil passage inside the valve body 11. When the oil pressure of the pump port 12, which is applied to the rear oil chamber 14 through the hole 11b, moves the oil pressure setting spring 10 forward by a slight amount against the force of the oil pressure setting spring 10,
The pump port 12 and the relief port 13 are communicated through the annular groove 11a, and the pressure regulating valve 7 is caused to perform a relief operation. The tip of the oil pressure setting spring 10 is received by a control piston 15 whose most advanced position is regulated by an annular step 9a on the inner peripheral surface of the valve case 9. Another pump port 35 is provided in the valve housing 8 on the rear side of the control piston 15 , and the pump port 12 and the pump port 35 are connected to the oil supply circuit 4 by a connecting circuit 22 .

As shown in Figures 1 and 2, the pump port 35
An oil passage 3 that communicates with the back of the control piston 15
6 is formed in the valve case 9, and a solenoid valve 30 as described below is provided in this oil passage 36. That is, as clearly shown in FIG. 2, an annular stepped portion 36a is formed in a portion of the oil passage 36 along the axial direction of the case 9, and a tapered portion 37a spanning the front and back sides of the annular stepped portion 36a is provided at the tip of the valve. The body 37 is slidably inserted into the valve case 9 from the outside, and has an annular stepped portion 36a and a tapered portion 37.
The oil passage 36 is constricted between a and a constrictor 38. The valve body 37 is biased by a relatively weak spring 39 to move in a direction that reduces the degree of aperture of the aperture 38. Further, the valve body 37 has a valve case 9.
A coil 40 is wound outside, and this coil 40
When energization is performed, the valve body 37 is energized to move in a direction to increase the degree of restriction of the throttle 38. A mechanism (not shown) is provided between the valve body 37 and the valve case 9 to prevent the valve body 37 from coming off while allowing the valve body 37 to slide within a predetermined range. As shown by the chain line in FIG. 2, it is provided so as to be movable to a position where the oil passage 36 is opened and the function of the throttle 38 is released. Note that the spring 39, which is one component of the solenoid valve 30, can also be provided in a solenoid valve case (not shown) that should cover the coil 40.

As shown in FIG. 1, a resistance thermometer 41 constituting a temperature sensor is provided inside the oil tank 3.
This resistance thermometer 41 is connected in series with the coil 40 and variable resistor 42, and then connected to a power source 43.

Similarly, as shown in FIG. 1, a sensor switch 45 is also inserted into the operation control circuit of the solenoid valve 30, and this sensor switch 45 is constructed as follows. That is, as shown in FIG. 3, the sensor switch 45 is connected to the valve case 8.
The spool 6a is fitted into the valve hole of the spool 6a to form the switching valve 6. Spool 6
a moves forward 1 when pulled out from the neutral position N shown in the figure.
It is assumed that the gear is sequentially moved to the forward speed position F ₁ , the forward 2nd speed position F ₂ , and the forward 3rd speed position F ₃ , and when it is pushed from the neutral position N, it is moved to the reverse 1st speed position R. The rod part of the spool 6a has a spool 6
The annular slots 46F ₁ , 46F ₂ , 46F ₃ , 4 will be located facing the sensor switch 45 when a is moved to each of the above operating positions F ₁ , F ₂ , F ₃ , R.
6R is formed. The sensor switch 45 is a mover 4 that turns off the switch 45 when pushed in.
A ball 45b is attached to the tip of the movable element 45a, the half of which can be fitted into each of the slots 46F ₁ , 46F ₂ , 46F ₃ , 46R, and brought into contact with the rod of the spool 6a. There is. Based on the above, the sensor switch 45 is configured such that when the spool 6a is at the neutral position N and when the spool 6a is slid between the positions N, F ₁ , F ₂ , F ₃ , and R, the movable element 45 a is When the spool 6a is pushed into the circumferential surface of the rod and takes the OFF state, and the spool 6a is moved to each operating position F ₁ , F ₂ , F ₃ , R, half of the ball 45b is pushed into each slot 46F ₁ ,46F ₂ ,46
By fitting into F ₃ , 46R, the movable element 45a protrudes and assumes an on state.

Next, to explain the operation of the embodiment, the switching valve 6 or its spool 6a is at each operating position F ₁ ,
When it is shifted to F ₂ , F ₃ , R, the sensor switch 45 is turned on as described above, so that the coil 40 of the solenoid valve 30 is energized, and the valve body 37 of the solenoid valve 30 is activated by the force of the spring 39 and the coil 40. 40. Take a position where the electromagnetic auxiliary force due to energization is balanced. Hydraulic oil is supplied behind the control piston 15 from the oil supply circuit 4 through a throttle 38 formed between the annular stepped portion 36a and the tapered portion 37a of the valve body 37, so that the control piston 15 gradually moves. By moving the clutch forward, the clutch operating oil pressure is gradually increased. This oil pressure gradual increase is performed as follows. That is, as the oil pressure in the oil supply circuit 4 is increased by the advance of the control piston 15, the oil pressure acting on the front surface of the valve body 37 located behind the control piston 15 is also increased, so that the valve body 37 is moved by the force of the spring 39. At the same time, such oil pressure also biases the throttle 38 in the direction of reducing the degree of restriction, and therefore, the degree of restriction of the throttle 38 becomes smaller as the oil pressure of the oil supply circuit 4 increases. Therefore, the control piston 15 advances slowly at the beginning, and accelerates as the oil pressure in the oil supply circuit 4 increases.
From this, the switching valve 6 is moved to each operating position F ₁ , F ₂ ,
As shown in FIG. 4, the rise of the clutch working oil pressure P as time t elapses after the shift to F ₃ and R becomes steeper as time t elapses. Such a gradual increase in oil pressure tends to cause a shock at the beginning of the engagement process of the hydraulic clutch, and rather than when the friction elements of the hydraulic clutch are fully engaged, the hydraulic pressure gradually increases to the normal working oil pressure P ₀ . Since it is desirable to rapidly increase the oil pressure P and quickly reach a steady state, this is an almost ideal form.

When the temperature of the hydraulic oil rises, the resistance value of the resistance thermometer 41 in the oil tank 3 decreases, so the current value flowing through the coil 40 increases, and therefore the valve body 37
The degree of aperture of the diaphragm 38 is increased by increasing the electromagnetic force. Therefore, even though the viscosity of the hydraulic oil decreases due to a rise in oil temperature, the clutch action oil pressure can be gradually increased regardless of the rise in oil temperature, and smooth engagement of the hydraulic clutch can be achieved regardless of oil temperature fluctuations. It is always obtained in a constant manner. The manner in which the clutch hydraulic pressure is gradually increased can be optimally adjusted by adjusting the resistance value of the variable resistor 42.

Furthermore, when the switching valve 6 or its spool 6a is at the neutral position N and when it is displaced between the positions N, F ₁ , F ₂ , F ₃ , and R, the sensor switch 45 in the solenoid valve operation control circuit is turned off. Therefore, in addition to the neutral position N of the switching valve 6, the switching valve 6 can be moved to each operating position F ₁ , F ₂ , F ₃ ,
Also when moving to R, the current to the coil 40 is temporarily cut off. When the current to the coil 40 is cut off in this way, the valve body 3
7 moves back significantly and the diaphragm 38 function is canceled.
Therefore, when operating the switching valve 6 to each position, the oil passage 36, tank port 35, connection circuit 22, oil supply circuit 4 and switching valve 6 are connected from behind the control piston 15.
The oil is quickly drained into the oil tank 3 through.

This invention has the effect of compensating for temperature fluctuations in the hydraulic oil so that the hydraulic pressure applied to the hydraulic clutch can be gradually increased almost uniformly at all times, and when changing gears, the hydraulic pressure can be quickly removed from behind the control piston to remove the control piston. As described above, the effect of reliably retracting to a position where the oil pressure is gradually increased from a low oil pressure is achieved.

This invention has a structure with a single solenoid valve 30 that solves both the two problems of the conventional one, so each problem can be addressed with a separate structure (for example, the degree of aperture is controlled by a temperature sensor). The structure is simpler than in the conventional case, in which a variable aperture is provided separately, and a solenoid valve is opened and opened by a sensor switch that detects the speed change operation.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view and hydraulic and electrical circuit diagrams showing an embodiment of this invention, Fig. 2 is an enlarged longitudinal cross-sectional view of the main part of Fig. 1, and Fig. 3 is a longitudinal cross-section of a part of the same embodiment. FIG. 4 is a schematic graph showing the effect of the same embodiment. 1...Power shift shaft, 2F ₁ , 2F ₂ , 2F ₃ ,
2R...Hydraulic clutch, 4...Oil supply circuit, 6...
Switching valve, 7... Pressure regulating valve, 8... Valve housing, 9... Valve case, 9a... Annular step, 1
0... Spring for oil pressure setting, 11... Valve body, 1
2...Pump port, 13...Relief port,
15...Control piston, 22...Connection circuit, 30
... Solenoid valve, 35 ... Pump port, 36 ... Oil passage, 36a ... Annular step, 37 ... Valve body, 37
a...Tapered part, 38...Aperture, 39...Spring, 40...Coil, 41...Resistance thermometer,
42...variable resistor, 43...power supply.

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 is provided with a pressure regulating valve configured to act behind a control piston via a throttle, and the oil is supplied to an oil passage 36 connecting the oil supply circuit 4 to the rear of the control piston 15. A solenoid valve 30 is provided with a valve body 37 that can be moved to a position where the passage 36 is variably throttled and the throttle action is released, and the solenoid valve 30 constitutes the throttle 38. A temperature sensor 41 that senses the temperature and a sensor switch 45 that senses the displacement operation of the switching valve 6 that switches and controls the supply and discharge of hydraulic oil to the hydraulic clutches 2F ₁ , 2F ₂ , 2F ₃ , and 2R are provided. A temperature sensor 41 and a sensor switch 45 are disposed in the operation control circuit of the electromagnetic valve 30 so that the higher the temperature of the hydraulic oil sensed by the temperature sensor 41, the more the valve element 37 is displaced to increase the degree of constriction of the oil passage 36. Sensor switch 45 while being forced
The valve body 37 is moved by the switching valve displacement operation sensed by
1. A hydraulic control device for a hydraulic clutch type transmission, characterized in that the hydraulic control device is inserted and installed so as to be temporarily displaced to a throttle action release position.