JPH0255667B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an improvement of a hydraulic control device, and is used in power shift transmissions of industrial vehicles, forklifts, etc.

(Prior art) As a prior art related to the present invention, for example, JP-A-59
- There is something described in Publication No. 81231.

This includes oil pump, regulator valve,
This is a hydraulic system consisting of an inching valve, selector valve, change valve, modulator valve, and clutch servo.The first oil path runs from the oil pump to the selector valve via the regulator valve and inching valve, and the This hydraulic system has a second oil passage leading to the valve and the clutch servo, and third and fourth oil passages running from the change valve to one side and the other side of the modulator valve, and the supply pressure to the clutch servo is as follows: The oil pressure corresponding to the oil pressure regulated by the modulator valve is transmitted from the oil pump through the first oil path to the change valve side via the second oil path and the third and fourth oil paths to the clutch servo side. It enters the second oil passage to the supply pressure.

(Problems to be Solved by the Invention) However, the following problems occur in the above-mentioned prior art. In other words, there is a pressure loss between the oil pressure at the branch point between the clutch servo side oil path and the change valve side oil path of the second oil path, and the oil pressure at the entrance point of the third oil path to the modulator valve. Therefore, the pressure at the modulator valve is adjusted to generate an appropriate supply pressure to the clutch servo after taking this loss into account, but the hydraulic condition changes depending on the select position of the selector valve. The loss pressure mentioned above is not necessarily constant because there is resistance to the oil pressure due to change valves, and the oil flow rate may change depending on the engine rotation.
Clutch operation was inconsistent.

The technical object of the present invention is to reduce the above-mentioned pressure loss and reduce variations in clutch operation.

[Structure of the invention]

(Means for Solving the Problems) The technical measures taken to achieve the above technical problem are the first oil path leading from the oil pump to the selector valve via the regulator valve and the inching valve, and the selector valve. A second oil passage from the change valve to the clutch servo, a third oil passage from the change valve to one side of the modulator valve, and a first oil passage between the inching valve and the selector valve to the modulator. A hydraulic system is configured from the fourth oil passage leading to the other side of the valve.

(Function) With the above technical means, on one side of the modulator valve, the fourth oil passage is arranged from between the inching valve and the selector valve without passing through the first oil passage and the selector valve and the change valve. Since hydraulic pressure is supplied directly through the valve, there is no pressure loss due to the select position of the selector valve or the resistance of the change valve. Therefore, the pressure supplied to the clutch servo is regulated by the modulator valve.

(Example) The present invention will be explained below based on examples.

FIG. 1 shows a flowchart of an embodiment of the hydraulic system of the present invention. That is, oil pump → regulator valve → inching valve → each clutch F-
In the oil passage configured as a C/L, R-C/L servo, the oil passage is further connected to the selector valve → change valve → modulator valve. Further, an oil passage is connected from an oil passage between the inching valve and the selector valve to the modulator valve.

FIG. 2 shows the detailed hydraulic circuit of this embodiment. An oil pump 1 serving as a hydraulic pressure source is rotated by an engine output shaft (not shown). oil pump 1
The discharge port is connected to the input port b of the regulator valve 10 via a line 30, which is a part of the first oil path, and is branched off and connected to the torque converter T/C via the orifice 4, and further lubricates the It is supplied as oil to the lubricating part of the clutch.

The output port a of the regulator valve 10 is the first
It is connected to the port f of the inching valve 20 via a line 31 which is another part of the oil passage, and its output port g is connected to the line 3 which is another part of the first oil passage.
2 to the input port c of the selector valve 40. Each output port b, d of the selector valve 40 is connected to a respective clutch R-C/L, F-C/L.
It is connected to the servo via lines 33 and 33' which are second oil passages, and is also connected to each input port a and b of the change valve 50.

The output port c of the change valve 50 is connected to the modulator valve 6 via a line 34 which is a third oil passage.
0 to input port f on one side. line 32
is input to input ports a and b on the other side of the modulator valve 60 via a branch line 32' which is a fourth oil passage. Each port c of the modulator valve 60,
The drained oil from d and e returns to the oil pan 2 via line 35. On the other hand, the drained oil from the discharge ports a and e of the selector valve 40 returns to the oil pan 2 via the line 35'.

Drain oil from the regulator valve 10 is at ports c and d.
From there, it returns to oil pan 2 via line 35.

The regulator valve 10 itself may be of a known type, and the spool 11 is formed by balancing the urging force of the spring 15 with the input pressure acting on the lands 12, 13, 14 in opposition to this, that is, the pressing force due to pressure regulation. Pressure regulation is performed by changing the degree of opening of the oil chamber 16 and the land 12.

The selector valve 40 is a known one, and selectively connects or closes the input port c to the output ports b and d by switching the forward direction F and backward direction R of the spool 41 having two lands 41a and 41b.

The change valve 50 selectively supplies one of its outputs to the modulator valve 60 in response to switching of the selector valve 40 between forward F and backward R.

The modulator valve 60 may be a known one,
The spool 6 has a land 61a and presses against the piston 62 with a spring 63 interposed between the spool 6 and the piston 62.
1. It has a second piston 64 (controls ports e and f) which has an orifice 64a and is urged leftward by a spring 65. Modulator valve 6
0 moderates the degree of change in the output pressure of the inching valve 20, that is, the clutch pressure applied to the servos of each clutch FC/L and RC/L.

One of the clutches F-C/L and R-C/L is engaged, and the other is released, depending on the F and R positions of the selector valve, respectively. In the N position both are released.

The inching valve 20 has an inching spool 21 provided with lands 21a, 21b, and 21c that are biased in opposing directions by first and second springs 23 and 24 in a cylinder and control input pressure. An inching rod 22 is also disposed coaxially within the cylinder and presses the inching spool 21 via a first spring 23.
is operated in the direction of arrow A in conjunction with a pedal (not shown, such as an inching pedal or a brake pedal). Inching rod 22 is land 22
a, 22b, and supplies the input pressure from the line 32 to the oil chamber 25 through ports a, b, and i when it is not in operation (the lower half of Fig. 2 20), and when it is in operation (the upper half of Fig. 2). For the half part), first close port a, then open discharge port c when further stroked, and oil chamber 25
Cuts off and releases the input pressure to. In order to ensure such operation, the length between port a and port c (the shortest length of the inner edge part) L1 and land 2
The relationship between L2, the length between 2a and 22b (the shortest length of the edge part), is L1>L2, and preferably, if L1-L2=l, l is 0.5 to 1.0 mm.
is set to

The spool 21 forms an oil chamber 26 between a land 21a and a land 21b, and the land 21a restricts the input port f to a direction in which it is closed when the pedal is operated. The land 21b of the spool 21 closes the discharge port h when it is not in operation, and opens when it is in operation.

The discharge port d constantly communicates the housing chamber of the spring 23 with the discharge line 35.

Ports a, e, and g communicate with line 32 via constricted portions 28a, 28e, and 28g, respectively.

The operation of this inching valve 20 will be explained below. The state when the pedal is not depressed (non-actuated) is shown in the lower half of FIG. g to line 32
Go out. The line 32 enters the oil chamber 25 through ports a, b, and i, and together with the spring 24 pushes the spool 21 to the left. The line 32 also pushes the spool 21 to the right through port e.

However, since the leftward pressing force is large, Fig. 2
The state of the lower half of 0 is maintained, and the discharge port h is closed. Therefore, the input pressure from the regulator valve 10 is the orifice 2 after the inching valve 20.
8a, 28e, and 28g are maintained in the line 32, enter the selector valve 40, and the line 3
2' to ports a and b at the left end of the modulator valve 60 to regulate the pressure in the line 32. This adjustment pressure is supplied to F via lines 33, 33'.
-C/L, R-Since it goes into the C/L servo, the pressure loss at the change valve 50 is not taken into consideration.

When you start depressing the pedal, the inching rod 22 moves in the direction of arrow A, almost reaching the input port a.
leading to the closure. When the pedal is further depressed, the exhaust port c opens to release the pressure. Therefore, the pressure in the oil chamber 25 becomes a pressure corresponding to the difference in repulsive force between the spring 23 and the spring 24, and the spool 21 moves gently to the right in response to the opening of the discharge port c, as shown in FIG. 20. Shifts to the position shown in the upper half of the figure, the pressure in the line 32 decreases, and the F-C/
L, R-C/L is released.

〔Effect of the invention〕

The present invention produces the following unique effects. That is,
The spool 61 of the modulator valve 60 is in a position like the upper half of Fig. 2 60 when the engine is stopped, but as the engine rotates, the line 3
2', the spool 61 is at a position like the lower half and the pressure is always regulated. Therefore, unlike the prior art, there is no possibility that the spool 61 moves back and forth between the upper half position and the lower half position every time the selector valve is returned to the N position by selecting the selector valve, causing a stagnation. .

[Brief explanation of the drawing]

FIG. 1 is a flow chart of the present invention, and FIG. 2 is a hydraulic circuit diagram showing an embodiment of the present invention. 10... Regulator valve, 20... Inching valve, 30, 31, 32... First oil path, 3
2'...Fourth oil path, 33, 33'...Second oil path, 3
4...Third oil passage, 40...Selector valve, 50
...Change valve, 60...Modulator valve.

Claims (1)

[Claims] 1 Oil pump, regulator valve, inching valve, selector valve, change valve,
In a hydraulic system comprising a modulator valve and a clutch servo, a first oil passage runs from the oil pump to the selector valve via the regulator valve and the inching valve, and from the selector valve to the change valve. A second oil passage leading to the clutch servo, a third oil passage from the change valve to one side of the modulator valve, and a first oil passage between the inching valve and the selector valve to the modulator. A hydraulic device having a fourth oil passage leading to the other side of the valve.