JP2003343607A - Hydraulic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effect smooth speed change by relaxing a speed change shock accompanied with engagement and disengagement of a hydraulic clutch, in a hydraulic transmission having a hydraulic mechanism wherein a hydraulic clutch is provided in a running transmission system, the clutch is disengaged when gear change is started, and the clutch is engaged when speed change is completed. <P>SOLUTION: A shuttle valve 15 serving both as an oil feed pipe is arranged between a hydraulic mechanism 5 and a hydraulic clutch 12. A spool 18 is inserted in a poppet 17 integrally situated in the element of the shuttle valve 15, and a flow passage 20 connected to a throttle 18b of the spool 18 and an auxiliary flow passage 20a communicated with the hydraulic clutch 12 side through the throttle flow passage 20 are bored. A function where by energizing the spool 18 by a spring in a direction in which the auxiliary flow passage 20a is closed, pressure oil is rapidly discharged when the hydraulic clutch 12 is disengaged, and a function where when the hydraulic clutch 12 is engaged, a pressure oil charge flow rate to the hydraulic clutch 12 is gradually decreased, are provided. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided in a non-clutch vehicle such as a tractor, and has a hydraulic clutch interposed in a traveling transmission system to "disengage" the hydraulic clutch when starting a shift.
Then, when the shift is completed, the hydraulic clutch is turned on.
The present invention relates to a hydraulic transmission having a hydraulic mechanism of

[0002]

2. Description of the Related Art Conventionally, as a hydraulic transmission equipped in a non-clutch vehicle such as a tractor, as disclosed in, for example, Utility Model Registration No. 2578029, a rotary transmission is connected to a shift operation of a shift lever. When the shift lever starts moving operation, the hydraulic clutch is in the “disengaged” state, and the hydraulic circuit of the rotary transmission valve is switched to operate the hydraulic actuator. The hydraulic mechanism is configured so that the hydraulic clutch is set to the “engaged” state at the time when the required speed change is completed by switching the internal gears in the hydraulic gear. A shuttle valve for controlling the on / off of the hydraulic clutch is arranged in the oil path, and the pressure oil in the hydraulic clutch is provided to the shuttle valve when the hydraulic clutch is turned off. And a function to discharge, to have a function to regulate the pressure oil-on flow rate at the time of the hydraulic clutch "containing"
It is known that the hydraulic transmission is configured to be compact and to improve responsiveness.

[0003]

However, in the above-mentioned prior art, the flow rate of the pressure oil injected into the hydraulic clutch when the hydraulic clutch is "engaged" is regulated by the throttle formed in the shuttle valve. If it is increased, the time lag until the hydraulic clutch is filled with hydraulic oil becomes large, and quick gear shifting cannot be performed. On the contrary, if the throttle amount is decreased, a so-called half-clutch state hardly occurs. There was a problem that the gear shift shock at the time became large.

[0004]

SUMMARY OF THE INVENTION The present invention was devised for the purpose of solving the above-mentioned problems. A hydraulic clutch is provided in a traveling transmission system, and the hydraulic clutch is In a hydraulic transmission having a hydraulic mechanism that is "disengaged" and has a hydraulic clutch that is "engaged" when shifting is completed, a shuttle valve is provided between the hydraulic mechanism and the hydraulic clutch, and the shuttle valve is First, it has a function of promptly discharging the pressure oil in the hydraulic clutch when the hydraulic clutch is "disengaged" and a function of gradually reducing the flow rate of the pressure oil input to the hydraulic clutch when the hydraulic clutch is "engaged". It is characterized by 1.

Then, a spool is inserted into a poppet installed in the body of the shuttle valve, and a throttle passage connected to the throttle and a sub passage communicating from the throttle passage to the hydraulic clutch are formed in the spool. In addition, the second feature is that the spool is biased by a spring in a direction in which the sub-flow path is closed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a tractor 1 to which the present invention is applied, and the tractor 1 is provided at a side of a control seat 2.
A travel speed change operation device 3 including a shift lever 3a and a speed change guide 3b in which N (neutral) shift positions 1 to 8 are shown is provided.

As shown in FIG. 2, a rotary type shift valve 6 which rotates in association with a shift operation of the shift lever 3a is provided, and when the shift operation is started by the shift lever 3a, a hydraulic clutch for traveling is provided. When the rotary shift valve 6 switches the hydraulic circuit, the first main shift cylinder 7, the second main shift cylinder 8 or the sub shift cylinder 9 that is a hydraulic actuator is turned off.
To retract the gears and switch the transmission gear group in the transmission case (not shown). Further, the hydraulic mechanism 5 is configured so that the hydraulic clutch is in the “engaged” state at the time when the required gear shift is completed. That is, in this configuration, the multi-disc friction type hydraulic clutch 12 for traveling is automatically disengaged during a gear shifting operation to perform non-clutch gear shifting.

More specifically, the hydraulic mechanism 5 is a hydraulic actuator which is a hydraulic actuator for shifting the travel transmission through a rotary type shift valve 6 connected to a pump port 4 serving as a hydraulic source by an oil passage 4b. Main transmission cylinder 7,
The second main transmission cylinder 8 and the sub transmission cylinder 9 are connected to each other, and a sub oil passage 4a having a check valve 13 and a throttle valve 14 interposed therein is branched from the pump port 4, and the sub oil passage 4a is provided. Supplies pressure oil to the traveling hydraulic clutch 12 via the shuttle valve 15. Further, the oil passage 13a on the downstream side of the check valve 13 and the throttle valve 14 and the rotary transmission valve 6 are connected via the oil passage 6a.

Further, a rotatable spool is incorporated in the rotary type speed change valve 6, and the spool is changed and rotated in response to a change operation of the main speed change lever 3a to respond to each change operation. First hydraulic actuator
Of the main transmission cylinder 7, the second main transmission cylinder 8 and the sub transmission cylinder 9 are respectively retracted and operated to switch the transmission gear group in the transmission case (not shown) and 7,
The check valves 7b, 8b and 9b provided in parallel with the valves 8 and 9 are controlled to be opened and closed so that the pressure oil supplied to the shuttle valve 15 is returned to the oil tank T during the shift.

The auxiliary transmission cylinder 9 has an L
(Low) and H (High) are switched at the A and B ports,
Main transmission cylinder 7 switches between neutral N and first speed and second speed at ports C to E, and second main transmission cylinder 8 switches from neutral N to third speed and fourth speed at ports F to H. I am going to do it.

The shuttle valve 15 is shown in FIG.
As shown in (c), the shuttle valve which is interposed in the pressure oil path from the oil passage 13a on the downstream side of the check valve 13 and the throttle valve 14 to the traveling hydraulic clutch 12 and also serves as an oil supply pipe. A cylindrical poppet 17 installed in the main body 15a of 15 and a spool 18 coaxially inserted in the poppet 17 are axially moved in the pressure direction of the pressure oil to move the poppet 17 to the running hydraulic clutch 12 side. And a shuttle valve 15 corresponding to the valve seat 17a.
The seat 19 formed on the main body 15a is opened and closed, and the spool 18 is formed with a stopper portion 18a that expands in diameter toward the traveling hydraulic clutch 12.

More specifically, in the inside from the pressure oil supply side A of the spool 18 to the traveling hydraulic clutch 12 side,
A throttle passage 20 connected to the throttle 18b of the spool 18
And the stopper portion 1 of the spool 18
On the 8a side (the traveling hydraulic clutch 12 side), a sub-flow passage 20a is formed which is orthogonal to the throttle flow passage 20 and communicates therewith. In addition, 21 is a compression spring, and the compression spring 21 connects the poppet 17 to the hydraulic clutch port 1.
The valve seat 17a and the seat 19 of the poppet 17 are closed by urging it toward the 2a side. Reference numeral 22 is also a compression spring, and the compression spring 22 urges the sub-flow passage 20a communicating with the throttle passage 20 of the spool 18 to be closed by the inner surface of the poppet 17.

In the hydraulic mechanism 5 configured as described above, the shift guide 3 is operated by the shift lever 3a.
The control operation in the case of performing a shift operation from the 1st speed to the 2nd speed at each of the N (neutral) shift positions 1 to 8 shown in b will be described below.

From the first speed to the second speed by the shift lever 3a.
When the shift operation to the high speed is started, first, the rotary type speed change valve 6 is switched to supply the pressure oil to the E port of the first main speed change cylinder 7, and the piston of the main speed change cylinder 7 operates in the right direction in the figure. As a result, the check valve 7b attached to the main transmission cylinder 7 is opened, and the supply of the pressure oil to the shuttle valve 15 is stopped, so that the pressure difference generated in the poppet 17 causes the poppet 17 to resist the spring 21 in the figure. Move to the right, which causes the poppet 17
Valve seat 17a and its seat 19 are open,
The pressure oil in the traveling hydraulic clutch 12 is returned to the oil tank T via the pressure oil return ports 16 and 16, and the traveling hydraulic clutch 12 is quickly switched to the “disengaged” state. Also, during this period, the rotary transmission valve 6
Pressure oil is supplied to the E port of the main transmission cylinder 7 via the gear, and a shift fork (not shown) linked to the projecting / retracting operation of the main transmission cylinder 7 causes the transmission gear in the transmission case to move from the first-speed meshing up to 2 Switched to high speed gear mesh.

When the gear change is completed, the check valve 7b is closed, and the pressure oil is supplied from the check valve 13 and the throttle valve 14 to the shuttle valve 15 as shown in FIGS. Started at. First,
At the initial stage of pressure oil supply, as shown in FIG.
Due to the pressure difference with respect to the poppet 17, the poppet 17 is closed and the spool 18 inserted in the poppet 17 is pushed by the pressure oil to move to the left in the figure, and the throttle 18b formed in the spool 18 and the throttle passage 20 are connected to each other. A large amount of pressure oil is quickly supplied to the traveling hydraulic clutch 12 side through the sub-flow passages 20a that communicate with each other at right angles.

When the traveling hydraulic clutch 12 is filled with a certain amount of pressure oil and the traveling hydraulic clutch 12 is in a half-clutch state, the pressure difference between the front and rear of the spool 18 disappears and the spool 18 causes the spring 2 to move.
2, the auxiliary flow passage 20a is closed, and in the latter stage of the clutch connection, the pressure oil is flow-regulated by the throttle 18b of the spool 18 to the traveling hydraulic clutch 12 side. When supplied, the traveling hydraulic clutch 12 is slowly connected. When the pressure on the side of the traveling hydraulic clutch 12 reaches a required pressure, the traveling hydraulic clutch 12 is completely returned to the "on" state, that is, the connected state, and the tractor 1 in the second speed shift state. Runs.

According to the series of control operations of the shuttle valve 15 as described above, while the traveling hydraulic clutch 12 is in the state of "disengaged" to "engaged", a large amount of the hydraulic oil is initially supplied. While supplying the pressure oil to quickly bring the traveling hydraulic clutch 12 closer to the half-clutch state, the input flow rate is gradually reduced so that the traveling hydraulic clutch 12 is slowly connected in the latter period of the pressure oil supply. Since it is possible to alleviate the shift shock when the traveling hydraulic clutch 12 is connected while shortening the time required to connect the traveling hydraulic clutch 12, a smooth and speedy shifting operation can be performed. Like

Further, since the spool 18 for gradually reducing the flow rate of the pressurized oil can be compactly inserted in the poppet 17 installed in the main body 15a of the shuttle valve 15, the entire structure of the hydraulic mechanism 5 is extremely simple. Can be one.

[0019]

As described above, according to the hydraulic transmission of the present invention, while the traveling hydraulic clutch 12 is in the state of "disengaged" to "engaged", a large amount of the hydraulic oil is initially supplied. Of the hydraulic clutch 12 for traveling by supplying the pressure oil of
, The shuttle valve 15 has a function of gradually decreasing the input flow rate so that the traveling hydraulic clutch 12 is slowly engaged in the latter half of the pressure oil supply. As a result, the shift shock at the time of connecting the hydraulic clutch can be alleviated while shortening the time required for connecting the traveling hydraulic clutch 12, so that a smooth and speedy shift operation can be performed.

Further, a spool 18 is inserted into a poppet 17 installed in the main body 15a of the shuttle valve 15, and a throttle passage 20 connected to a throttle 18b of the spool 18 and a passage from the throttle passage 20 to the hydraulic clutch 12 side. Sub flow path 20a communicating
When the spool 18 is spring-biased in the direction in which the sub-flow path 20a is closed, a valve function for gradually reducing the flow rate of the pressure oil input can be compactly inserted into the shuttle valve 15, and the hydraulic pressure can be reduced. The entire structure of the mechanism 5 can be made extremely simple.

[Brief description of drawings]

FIG. 1 is a perspective view of a tractor.

FIG. 2 is a circuit diagram of a hydraulic mechanism.

FIG. 3A is a cross-sectional view of the shuttle valve at the initial stage of pressure oil supply in which the hydraulic clutch is in the “engaged” state. (B)
FIG. 7 is a cross-sectional view of the shuttle valve in the latter half of the pressure oil supply in which the hydraulic clutch is “engaged”. (C) is a cross-sectional view of the shuttle valve that puts the hydraulic clutch in the "disengaged" state.

[Explanation of symbols]

5 Hydraulic mechanism 12 hydraulic clutch 15 Shuttle valve 15a Shuttle valve body 17 poppets 18 spool 18b aperture 20 Throttle channel 20a Sub flow path

Claims (2)

[Claims] 1. A hydraulic clutch (12) is provided in a traveling transmission system, the hydraulic clutch (12) is "disengaged" when shifting is started, and the hydraulic clutch (1) is stopped when shifting is completed.
In a hydraulic transmission having a hydraulic mechanism (5) whose "2" is "on", a shuttle valve (15) is provided between the hydraulic mechanism (5) and the hydraulic clutch (12), and
The shuttle valve (15) includes the hydraulic clutch (12).
It has the function of quickly discharging the pressure oil in the hydraulic clutch (12) when it is "disengaged", and the function of gradually reducing the flow rate of pressure oil that is input to the hydraulic clutch (12) when it is "engaged". A hydraulic transmission that is characterized by 2. The body (15) of the shuttle valve (15)
A spool (18) is inserted into the poppet (17) installed in a), and a throttle channel (20) connected to the throttle (18b) is connected to the spool (18), and a hydraulic clutch from the throttle channel (20). The sub-flow path (20a) communicating with the (12) side is bored, and the spool (18) is spring-biased in a direction in which the sub-flow path (20a) is closed. Hydraulic transmission.