JPH078655U - Hydraulic circuit in speed change device - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to quickly return pressure oil from the hydraulic clutch port linked to the switching operation of the main shift and auxiliary shift levers, and to smoothly and reliably engage and disengage the hydraulic clutch and shift gears. Provided is a hydraulic circuit in a gear shift device capable of performing. [Structure] In order to return the pressure oil that has been pressure-fed to the hydraulic clutch port 10a to the oil tank 2 through the rotary valve 4, the spool 4b provided in the rotary valve 4 has an oil hole 16 that communicates with the hydraulic clutch port 10a.
And a sub oil passage 3a extending from the hydraulic clutch port 10a to the oil tank 2 is branched, and a switching valve 8b is interposed in the sub oil passage 3a to connect the rotary valve 4 to the hydraulic clutch port 10a. The switching valve 8b is configured to be closed by detecting the depressurization of the oil passages.

Description

[Detailed description of the device] [Industrial applications]

 The present invention is a hydraulic circuit of a speed change device that switches the speed change gear by performing on / off control of pressure oil via a rotary valve by an on / off switching operation of a hydraulic clutch linked to a switching operation of a main speed change and an auxiliary speed change lever. It is related to.

[0002]

[Prior art]

 In recent years, in mobile agricultural machines such as tractors, the hydraulic clutch is first automatically switched off by the switching operation of the main speed change lever or the auxiliary speed change gear lever, and then the rods of the main speed change cylinder or the auxiliary speed change cylinder corresponding to each of the above speed change levers. It is known that a shift change device is used that switches each shift fork by retracting operation, and can perform shift gear change operation without the need to depress the clutch pedal as in the past. As for the above-mentioned speed change device, the main clutch cylinder and the sub change cylinder connected to the disengagement of the hydraulic clutch and the disengagement of the hydraulic clutch are retracted and operated by the pressure oil switching supply of the rotary valve directly connected to the oil tank. , Was supplied to the hydraulic clutch via the rotary valve when the main shift lever or sub shift lever was switched. When the oil is returned to the oil tank side and the hydraulic clutch is disengaged, at the same time as the hydraulic clutch is disengaged, the main transmission cylinder with a check valve or the sub-transmission cylinder is connected to the hydraulic oil via a rotary valve. After pressure transmission, the gears are switched by the meshing of the transmission gears corresponding to the switching operation of the transmission lever, and then pressure oil is supplied again to the hydraulic clutch via the rotary valve to restore the connected state of the hydraulic clutch. The hydraulic circuit is adopted as ascribed.

In the hydraulic circuit configured as described above, in order to quickly supply the pressure oil to be pressure-fed to the hydraulic clutch, the hydraulic clutch port connected to the rotary valve is connected to the hydraulic clutch port via a check valve communicating with the oil tank. The oil passage is branched to stabilize the supply of pressure oil, and when the pressure rises more than necessary, it is configured to return the pressure oil to the oil tank side via this check valve. There is.

However, in the hydraulic circuit provided with the auxiliary oil passage having the check valve as described above, the pressure oil from the hydraulic clutch port passes through the oil hole formed on the spool in the rotary valve and the auxiliary oil passage. Since it is returned to the oil tank, the pressure oil does not easily escape to the oil tank, and the intermittent response of the hydraulic clutch is delayed, so that the hydraulic clutch, which is linked to the gear shift lever operation, can be operated stably and quickly. However, it has the drawback that it is difficult to do.

[0005]

[Problems to be solved by the present invention]

 The present invention was devised in view of the above circumstances to solve the conventional drawbacks, and its purpose is to detect a hydraulic clutch port linked to a main gear shift operation and an auxiliary gear shift lever switching operation. The present invention intends to provide a speed change device capable of promptly returning the pressure oil and smoothly and reliably engaging and disengaging the hydraulic clutch and changing the speed gear.

[0006]

[Means for Solving the Problems]

 In order to solve the problem, the technical means adopted by the present invention is to return the pressure oil pressure-fed to the hydraulic clutch port to the oil tank via the rotary valve. An oil hole communicating with the port is bored, a sub oil passage from the hydraulic clutch port to the oil tank is branched, and a switching valve is provided in the sub oil passage to connect the rotary valve to the hydraulic clutch port. The feature is that the switching valve is configured to be closed by detecting depressurization of the oil passage.

[0007]

[Action]

 Therefore, according to the present invention, the pressure oil from the hydraulic clutch linked to the operation of the shift lever can be quickly returned to the oil tank side, and smooth and reliable shift gear switching can be performed.

[0008]

EXAMPLE The configuration of the present invention will be described in detail based on an example shown in the drawings. In the figure, reference numeral 1 denotes a hydraulic circuit connected to an oil tank 2. The hydraulic circuit 1 includes a sub transmission cylinder 5, first and second main transmission cylinders 6 through a rotary valve 4 provided in a pump port 3. , 7 are connected, and a sub oil passage 3a, in which a check valve 8a and a switching valve 8b are interposed in series with the pump port 3, is provided in a branched manner, and further, a connection port 4a of the rotary valve 4 and a shuttle valve are provided. A hydraulic circuit 1 is constructed by connecting an output side 8c of the switching valve 8b to a connection portion with a hydraulic clutch port 10a communicating with the hydraulic clutch 10 via 9.

The rotary valve 4 is directly connected to the oil tank 2 via a rotatable spool 4b, and switches and rotates the spool in response to a switching operation of a main shift and an auxiliary shift lever (not shown). , The auxiliary transmission cylinder 5 and the rods 5a, 6a, 7a of the first and second main transmission cylinders 6, 7 are respectively retracted and operated to switch the transmission gear group in the center case (not shown). The check valves 5b, 6b, 7b provided in parallel with the cylinders 5, 6, 7 are controlled to open / close individually, and the pressure oil of the hydraulic clutch port 10a is returned to the oil tank 2.

On the other hand, the switching valve 8b is configured such that a pressure chamber 11a and a communication groove 11b are formed in the head portion and the intermediate portion of the sliding shaft 11, and the coil ammunition 12 is mounted in the base end portion. The pressure chamber 11a is connected to the connection side of the auxiliary oil passage 3a on the oil port 3 side and the hydraulic clutch port 10a via orifices 13 and 14, respectively. An output side 8c connected to the communication groove 11b and a switching oil passage 15 are branched in the respective oil passages of the sub oil passages 3a and the hydraulic clutch port 10a. Due to the operation, the communication groove 11b is switched to disconnect the connection between the output side 8c and the switching oil passage 15. Reference numeral 16 is an oil hole which is switchably connected to the connection port 4a and controls the inflow and outflow of pressure oil between the hydraulic clutch port 10a and the oil tank 2.

In the above structure, when the main transmission lever is switched from the 1st speed to the 2nd speed, the spool 4b of the rotary valve 4 first rotates in the direction of arrow A, and the oil hole 16 of the spool 4b moves. Instantly matches the connection port 12. At this time, since the connection port 12 communicates with the oil tank 2 side through the oil hole 16, the hydraulic oil pressure of the hydraulic clutch port 10a decreases and the hydraulic clutch 10 is disengaged. At this time, the pressure in the pressure chamber 11a of the switching valve 8b also drops at the same time, so that the sliding shaft 11 moves upward in the direction of the arrow B by the urging force of the coil ammunition 12 to move between the switching oil passage 15 and the output side 8c. Is blocked.

Here, the pressure oil of the hydraulic clutch port 10a is immediately supplied to the first main transmission cylinder 6 via the rotary valve 4 except for a small amount of pressure oil passing through the orifices 13 and 14, and the rod 5a appears and disappears. The speed change gear is switched to the second speed by the operation, the check valve 6 is opened, and the pressure oil in the hydraulic clutch port 10a is returned to the oil tank 2 via the check valve 6.

When the shift is completed, the check valve 6 is closed again, and the hydraulic pressure of the pressure chamber 11a is increased by the pressure oil passing from the oil port 3 through the orifice 13, so that the sliding shaft 11 becomes a coil ammunition. When the urging force of 12 is overcome to move downward in the direction of arrow C, the communication groove 11b communicates between the switching oil passage 15 and the output side 8c, the switching valve 8b is fully opened, and then the pump port 3 and the rotary valve 4 are opened. The pressure oil is pressure-fed to the hydraulic clutch 10 from the oil hole 16 of the spool 4b, and the hydraulic clutch 10 is returned to the connected state.

Therefore, the boosting force required for the hydraulic control corresponding to the speed change lever can be efficiently supplied to the speed change cylinder side by the pressure oil supplied to the hydraulic clutch 10, and a quick speed change operation can be performed. it can.

[0015]

[Effect of device]

 In short, according to the present invention, in order to return the pressure oil pumped to the hydraulic clutch port to the oil tank via the rotary valve, the spool installed in the rotary valve is provided with an oil hole communicating with the hydraulic clutch port. In addition, the auxiliary oil passage from the hydraulic clutch port to the oil tank is branched, and a switching valve is provided in the auxiliary oil passage to detect depressurization of the oil passage from the rotary valve to the hydraulic clutch port. Since the switching valve is configured to be closed, it is possible to improve the escape of pressure oil into the oil tank, and to quickly respond to the on / off response of the hydraulic clutch. Can be performed stably and quickly, and the efficiency of use of pressure oil can be improved. The can be miniaturized, can be performed intermittently and the speed change gear switching smooth and reliable hydraulic clutch, a shall of Sosu very useful practical effect.

[0016]

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a speed change device.

FIG. 2 (a) is an enlarged plan view of a part of a rotary valve in which some parts are omitted. (B) is an enlarged sectional view of the same as above.

[Explanation of symbols]

 1 hydraulic circuit 2 oil tank 3a secondary oil passage 4 rotary valve 4b spool 8b switching valve 10a hydraulic clutch port 16 oil hole

Claims (1)

[Scope of utility model registration request] 1. A pressure oil pumped to a hydraulic clutch port,
To return to the oil tank via the rotary valve,
An oil hole communicating with the hydraulic clutch port is bored in the spool installed in the rotary valve, and a sub oil passage extending from the hydraulic clutch port to the oil tank is branched and a switching valve is provided in the sub oil passage. A hydraulic circuit in a speed change device, characterized in that it is configured to close the switching valve by detecting pressure reduction in an oil passage from a rotary valve to a hydraulic clutch port. [0001]