JPH0411414B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inching control device for a transmission for an industrial vehicle.

There are various methods for controlling the inching operation of conventional industrial vehicle transmissions, particularly those that include a torque converter and include a hydraulically actuated friction engagement element (generally a clutch). Among them, for example, as disclosed in Japanese Patent Publication No. 52-34088, an inching valve is used in a hydraulic system as shown in Fig. 1: pressure source → pressure regulating valve → selector valve → change valve → modulator valve → clutch inching valve. There is a method of controlling the clutch pressure in inching by controlling the pressure regulating valve of the regulator valve using an inching valve in accordance with the stroke of depression of the brake pedal. As an inching valve, this method does not affect the modulator valve output pressure while the amount of pedal depression is small, and when the pedal depression exceeds a predetermined amount, the modulator valve outputs a control pressure that decreases as the amount of pedal depression increases. It acts on the clutch as pressure.

The modulator valve is arranged to smooth the engagement of the clutch, but with this method,
As shown in the graph of FIG. 1, residual pressure still occurs even when the displacement of the inching valve reaches its maximum range. This residual pressure causes the clutch to drag when the inching valve is fully stroked (when the pedal is fully depressed). This shortens the clutch life,
Furthermore, if the residual pressure becomes large, there is a risk that a start shock will occur when the pedal is slightly released. In other types of devices, for example, as shown in Figure 2, the clutch pressure (inching control pressure) changes depending on the oil temperature, engine speed, etc., and the clutch engagement start point (and release point) changes depending on the valve displacement. The disadvantage is that it cannot be determined precisely.

The present invention aims to eliminate the drawbacks of the conventional method as described above, and provides an inching control that generates a clutch pressure that accurately corresponds to the operating stroke of the inching valve and provides an inching control pressure that is not affected by the engine speed. Furthermore, it is possible to obtain an inching control device that does not generate residual pressure even during a full stroke, and in addition, to obtain an inching control device that does not cause sudden pressure fluctuations when the inching valve starts pressure control at the beginning of the operating stroke of the inching valve. An object of the present invention is to obtain an inching control device that prevents sudden pressure fluctuations from occurring even instantaneously over the entire valve operating region.

That is, in the inching control device of the present invention, the inching valve has a first control member 22 formed in the valve body and slidably disposed in a cylinder with one end open, and a second control member separate from the first sliding member. Part 2
1, the first control member is disposed on one end opening side of the cylinder having the same diameter, and one end of the first control member protrudes from the opening and is connected to an inching pedal or a brake pedal (not shown). The outer periphery of the first control member has a first land portion 22a and a second land portion 22b that can slide fluid-tightly on the inner wall of the cylinder, and the other end of the first control member faces one end of the second control member. A first elastic member 23 is disposed between one end of the second control member, and the second control member is disposed on the opposite side of the opening of the cylinder having a different diameter, and the second control member is disposed on the outer periphery of the second control member. has a third land portion 21a, a fourth land portion 21b, a fifth land portion 21c, and a sixth land portion 21d that can slide liquid-tightly on the cylinder inner wall, and the third land portion is connected to the first control member. The fourth land portion is formed at one end of the second control member facing the other end, and the fourth land portion is formed adjacent to the third land portion and has a cylinder inner wall with a diameter larger than the diameter of the cylinder in which the first control member is disposed, and the fourth land portion is formed adjacent to the third land portion and has a liquid The first oil chamber 27 is slidable tightly and has a first pressure receiving part of the second control member defined by a third land part, and the fifth land part has the same diameter as the fourth land part. The sixth land portion is formed in a stepped manner from the fifth land portion and is formed at the other end of the second control member, and the fourth and fifth land portions are disposed therein. The second oil chamber 25 has a second oil chamber 25 which is capable of liquid-tightly sliding on the inner wall of the cylinder having a diameter larger than the diameter of the cylinder, and has a second pressure receiving part of the second control member defined by the cylinder.
A second elastic member is disposed between the other end of the second control member in the oil chamber and the inner wall of the cylinder, and a plurality of ports are connected within the cylinder. The first land has a first input port a that can be opened and closed, and the fourth land has a second input port f that can be opened and closed, and the output port g that is output to the selector valve is located between the fourth and fifth lands. The hole 28 is connected to the first central oil chamber 26 and can communicate with the second input port according to the movement of the fourth land, and the hole 28 that constantly communicates the first central oil chamber and the first oil chamber is connected to the first central oil chamber 26 of the fourth land. 2 control members, and a second central oil chamber 29 between the first land portion and the second land portion and a second
A communication port that communicates with the oil chamber is formed, and the communication port is connected to the second central oil chamber and can communicate with the first input port according to the movement of the first land portion. It has a second communication port i that is connected to the oil chamber and can be opened and closed on the sixth land, and a discharge port that is discharged to the oil pan 2 has a first discharge port c that can be opened and closed on the second land. The first input port communicates with the second oil chamber via the communication port when the pedal is not depressed, and the second input port communicates with the output port. At the same time, when the pedal is depressed, the first input port is closed depending on the amount of pedal depression, and the second oil chamber is communicated with the first discharge port via the communication port to release the pressure in the second oil chamber. Further, as the second input port closes, the second discharge port begins to open and gradually reduces the pressure in the first oil chamber through the hole, and when the pedal is not depressed, the second discharge port begins to open.
The movement of the second control member, which is urged by the pressure of the oil chamber and the elastic force of the second elastic member, is restricted by the stepped portion of the sixth land portion.

Based on such a configuration, according to the present invention, the change in clutch pressure (therefore, the axle torque) according to the actuation stroke of the inching valve is made constant regardless of the engine speed, and the inching state (i.e., the clutch is half-closed) is maintained constant regardless of the engine speed. (state) to make the gradient of change gentle.

Further, when the inching valve is fully stroked in response to the full depression of the pedal, the residual pressure of its output pressure (therefore, the clutch pressure) is reduced to zero, reducing clutch drag and increasing clutch durability. Furthermore, by removing the residual pressure, the occurrence of a start shock when the pedal is released is prevented.

A particularly remarkable effect of the present invention is that when the pedal is not depressed, the movement of the second control member, which is biased by the pressure in the second oil chamber and the elastic force of the second elastic member, is controlled by the step of the sixth land portion. Since it is regulated by the attachment part, there is no need to provide special means to counter the pressure of the second oil chamber and the elastic force of the second elastic means in order to determine the position of the second control member when the pedal is not depressed. . Therefore,
The influence of the spring force of the inching pedal is eliminated, and the performance of the spring force of the inching pedal can be determined according to the operating feeling. Furthermore, since the first discharge port and the second discharge port are closed when the pedal is not depressed, a small-capacity hydraulic pressure source is required to maintain the line hydraulic pressure. Therefore, the inching control device becomes compact.

Further, as an aspect of the present invention, these hydraulic circuits are housed as a unit in one block,
To provide a compact and reliable inching control device.

The present invention will be explained below based on examples.

FIG. 4 shows a flowchart of an embodiment of the inching control device of the present invention. That is, in the oil path configured as the hydraulic source → pressure regulating valve → inching valve → selector valve → each clutch C/L1, C/L2, the oil path branched between the selector valve → each clutch is changed valve → modulator. connected to the valve.

FIG. 5 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). The discharge port of the pump 1 is connected to the input port b of the pressure regulating valve 10 via a line 30, and is branched off and connected to the torque converter T/C via an orifice 4, and is further supplied as lubricating oil to the lubricating part of the clutch. Ru.

Output port a of pressure regulating valve 10 is connected to ports a and b of inching valve 20 via line 31, and output port g thereof is connected to output port c of selector valve 40 via line 32. Each output port b, d of the selector valve 40 is connected to a line 33, 33' to the respective clutch C/L1, C/L2.
, and are also branched off and connected to each input/output port a, b of the change valve 50.

Output port c of change valve 50 is line 3
4 to input ports a and f of the modulator valve 60. Drained oil from each port b to e of the modulator valve 60 returns to the oil pan 2 via a 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'.

Drained oil from the pressure regulating valve 10 returns to the oil pan 2 from port c via the orifice 5 and line 38 on the one hand, and returns to the oil pan 2 via the filter 3 from port c' on the other hand.

The pressure regulating valve 10 itself may be of a known type, and the spool 11 absorbs oil due to the balance between the biasing force of the spring 15 and the input pressure acting on the lands 12, 13, 14 in opposition to this, that is, the pressing force due to pressure regulation. The pressure is adjusted by changing the opening degree of the land 12 between the chamber 16 and ports o and c'. still,
17 is a stopper pin for the spool 11.

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 a spool 41 having two lands. 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,
Although a detailed explanation will be omitted, from the left, a spool 61 which has a land 61a and presses against each other with a spring 63 interposed between it and a piston 62, and an orifice 64a.
The second piston 64 (controls ports e and f) is biased leftward by a spring 65. The modulator valve 60 adjusts the degree of change in the output pressure of the inching valve 20, that is, the clutch pressure applied to the clutches C/L1 and C/L2.

One of the clutches C/L1 and C/L2 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 resolved.

The inching valve 20 is a separate spool type in which the inching rod has a spool that is pressed by a spring, and the spool is backed by a spring in the opposite direction, and its control pressure and input pressure act against each other on the piston portion of the spool. Use the one.

The inching valve 20 has an inching rod 22 (hereinafter referred to as rod 22) formed in the valve body and slidably disposed in a cylinder with one end open.
and inching spool 2, which is separate from rod 22.
1 (hereinafter referred to as spool 21). (new line)
The rod 22 is disposed on the opening side of one end of the cylinder having the same diameter, and one end of the rod 22 protrudes from the opening and is connected to an inching pedal or a brake pedal (not shown). Further, the outer periphery has a first land 22a and a second land 22b that can slide on the cylinder inner wall in a liquid-tight manner. A first spring 23 is disposed between the other end of the rod 22 and one end of the spool 21 facing the other end. (Line break) The spool 21 is disposed on the opposite side of the cylinder openings having different diameters, and has a third spool 21 on its outer periphery that can slide liquid-tightly against the inner wall of the cylinder.
Land 21a, 4th land 21b, 5th land 2
1c and a sixth land 21d. The third land 21a is formed at one end of the spool 21 facing the other end of the rod 22. 4th land 21b
is formed next to the third land 21a, and the rod 2
2 can slide liquid-tightly on the inner wall of the cylinder, which has a diameter larger than that of the cylinder in which it is disposed. Furthermore, a first oil chamber 27, which is defined together with the third land 21a and serves as a first pressure receiving portion of the spool 21, is formed in the fourth land 21b. The fifth land 21c is slidably formed in a cylinder having the same diameter as the fourth land 21b. The sixth land 21d is formed in a stepped shape from the fifth land 21c, and is formed at the other end of the spool 21. Further, the sixth land 21d is capable of liquid-tightly sliding on the inner wall of the cylinder, which has a diameter larger than that of the cylinder in which the fourth and fifth lands 21b and 21c are disposed, and furthermore, the sixth land 21d is defined together with the cylinder and is attached to the spool 21. Second oil chamber 2 serving as the second pressure receiving part
5 is formed. (Line break) A second spring 24 is disposed between the other end of the spool 21 in the second oil chamber 25 and the inner wall of the cylinder. (Line break) Multiple ports are connected inside the cylinder, and the pressure regulating valve 10
The input port for receiving input is the first land 22a.
a first input port a that opens and closes according to the movement of the
The second land 21b opens and closes according to the movement of the fourth land 21b.
It has an input port f. On the other hand, the output port g that is output to the selector valve is connected to the first central oil chamber 26 between the fourth land 21b and the fifth land 21c, and communicates with the second input port f according to the movement of the fourth land 21b. It is possible. Further, a hole 28 is bored in the spool 21 so that the first central oil chamber 26 and the first oil chamber 27 are constantly communicated with each other. Furthermore, the first
A communication port that communicates between the second central oil chamber 29 and the second oil chamber 25 between the land 22a and the second land 22b is formed, and the communication port is connected to the second central oil chamber 29 and A first communication port b that can communicate with the first input port a according to the movement of the land 21a, and a sixth land 21 that is connected to the second oil chamber 25.
and a second communication port i that is opened and closed in accordance with the movement of d. Exhaust ports are formed to discharge to the oil pan 2, and a first exhaust port c opens and closes according to the movement of the second land 21b, and a second exhaust port c opens and closes according to the movement of the fifth land 21c. It has a port h and two other exhaust ports d and e. (Line break) The relationship between the ports and lands mentioned above is
When the inching pedal is not depressed, the first input port a
is configured to communicate with the second oil chamber 25 via communication ports b and c, and the second input port f is configured to communicate with the output port g. Furthermore, when the pedal is depressed, the first input port a is closed depending on the amount of pedal depression, and the second oil chamber 25 is communicated with the first discharge port c via the communication ports b and i. Furthermore, as the second input port f closes, the second discharge port h begins to open, gradually reducing the pressure in the first oil chamber 27 via the hole 28.
(Line break) Also, when the pedal is not depressed, the movement of the spool 21, which is biased by the pressure in the second oil chamber 25 and the spring force of the second spring 24, is controlled by the movement of the sixth land 21.
It is regulated by the stepped portion 21e of d. (Line break) Furthermore,
The length between the first input port a and the first discharge port c (the shortest length of the inner edge) L1 and the first and second lands 22a, 22b (the shortest length of the inner edge) c) The relationship with L2 is L1>L2, and preferably L1-L2=l,
l is set to 0.5 to 1.0 mm.

The operation of this inching valve 20 will be explained below. Figure 5 20 shows the state when the pedal is not depressed.
As shown in the upper half, the output pressure of the pressure regulating valve 10 is inputted to the input ports a and f via the line 31, and from the first input port a reaches the second oil chamber 25 via the communication ports b and i. Push the spool 21 to the left together with the second spring 24. On the other hand, input pressure also acts from the second input port f to the first oil chamber 27 via the second central oil chamber 26 and the hole 28, and the first spring 23
At the same time, the spool 21 is pushed to the right. Since the leftward pressing force is large, the state shown in the upper half of FIG. It is guided to valve 40.

In this case, the neutral N (sixth
(state in the figure), depending on the forward F and reverse R positions, each clutch is disconnected, input is input to C/L1, input is input to C/L2, and the output is gradually applied to the modulator valve 60 via the change valve 50. A regulated pressure is applied to each clutch.

When the pedal begins to be depressed, the inching rod 22 begins to move in the direction of arrow A, closing the first input port a. When the pedal is further depressed, the first discharge port c opens and the pressure in the second oil chamber 25 is released. Therefore, the spool 21
Since the pressure in the oil chamber 25 is only the pressure corresponding to the difference in elastic force between the first spring 23 and the second spring 24, it moves gently to the right in response to the opening of the first discharge port c, and the fifth An intermediate position between the position shown in the lower half of FIG. 20 is taken. At this time, the second discharge port h begins to open and the second input port f begins to close, so that the oil pressure in the first central oil chamber 26 drops from the initial pressure in steps. At that time, the first oil chamber 2
7 is equal to the oil pressure in the first central oil chamber 26, the spool 21 is moved to the right by the right movement of the rod 22.
Rightward pressing force of spring 23 and first land 21
The position is taken in accordance with the balance between the resultant force of the rightward pressing force from the first oil chamber 27 acting on a and the force of the second spring 24.

The process up to now is p- in the graph of Figure 3.
The clutch pressure, represented as a curve from qr to s, is traced according to the displacement of the inching valve. At this time, the pressure fluctuates at point r, and there is no such phenomenon as shown by the two-dot chain line, for example.

When the pedal is further depressed, the pressing force of the first spring 23 increases, so the pressure in the first oil chamber 27 gradually decreases, and the spool 21 gradually moves to the right and finally reaches the position where the second input port f is closed. (lower half of Figure 5). At this time, the second discharge port h is opened at the same time, and as a result, the output pressure to the line 32 becomes zero. At almost the same time, the tip 22 of the inching rod
When c comes into contact with the inching spool 21 and is further depressed, the inching spool 21 is moved to the right without using the spring 23 to maintain the output pressure at zero. (Point s on the graph in Figure 3).

When the pedal is gradually returned from the fully depressed position, the above stroke progresses in the opposite direction, and when the pedal returns to the predetermined position, it reaches the step at point r-q, and the output pressure of the pressure regulating valve 10 is directly output to the line 32. . When the pedal is further released, the inching rod 22 is completely restored to its original position, and the output pressures are equal during this time.

The present invention is based on the above configuration, and as shown in FIG. 3, the output pressure (control pressure) of the inching valve during inching operation is controlled by the inching rod 22 and the output pressure (control pressure) of the inching valve, rather than the spool 21 being directly actuated by depressing the pedal. The output pressure is transmitted to the spool 21 via the first spring 23, and the spool 21 is under the action of the opposing second spring 24 and moves according to the resultant force of the control pressure and the acting force of the spool 21. shows a certain change depending on the displacement of . Therefore, as shown by the dotted line in Figure 3,
Even when the engine speed is low and the output pressure from the pressure regulating valve is low, the output pressure of the inching valve can be changed to a certain degree according to the displacement of the valve. That is, fluctuations in axle torque (clutch pressure) caused by changes in the amount of oil from the hydraulic source when the pedal is depressed are alleviated.

In response to the displacement of the inching rod 22, the input pressure to the second oil chamber 25 is first cut off, and then the pressure inside the second oil chamber 25 is exhausted, so that the inching valve 21 is in a gentle pressure regulating state (the lower half of the fifth Since the state shown in FIG. 3 can be shifted to the state shown in FIG. Therefore, a start shock is prevented when the gear is changed simultaneously with the inching pedal return. Also, the pressure regulating valve 10
In this case, the spool is also prevented from suddenly operating due to the above-mentioned pressure fluctuations, thereby preventing damage to the contact portion with the stopper or the spring holding portion.

As is clear from the above explanation, when the pedal is fully depressed, the output of the inching valve becomes zero and no residual pressure is generated.

Furthermore, as a particularly remarkable effect of the present invention, when the pedal is not depressed, the pressure in the second oil chamber 25 and the pressure in the second oil chamber 25 are increased.
The movement of the spool 21 urged by the spring force of the spring 24 is controlled by the stepped portion 21 of the sixth land 21d.
Since the pressure is regulated by e, there is no need to provide special means to counter the pressure of the second oil chamber 25 and the spring force of the second spring 24 in order to determine the position of the spool 21 when the pedal is not depressed. Therefore, the influence of the spring force of the inching pedal is eliminated, and the performance of the spring force of the inching pedal can be determined in accordance with the operating feeling. Furthermore, since the first discharge port c and the second discharge port h are closed when the pedal is not depressed, a small-capacity hydraulic power source is required to maintain the line hydraulic pressure. Therefore, the inching control device becomes compact.

In the above embodiment, a pair of springs (first,
Although the second) and the pair of pressure receiving parts (first and second) are arranged with respect to the spool 21, each of these elements can be configured as a combination of two or more elements.

Next, FIG. 6 shows a sectional view of a device incorporating the above-described embodiment as one block. Thus, the device of the present invention can be constructed as a compact unit, easy to assemble into a vehicle, and easy to maintain.

[Brief explanation of drawings]

1 and 2 are graphs showing the relationship between valve displacement and clutch pressure according to the conventional method, FIG. 3 is a graph showing the relationship between valve displacement and clutch pressure according to an embodiment of the present invention, and FIG. 4 is a graph showing the relationship between valve displacement and clutch pressure according to an embodiment of the present invention. A flowchart of an embodiment of the present invention, FIG. 5 is a hydraulic circuit diagram showing an embodiment of the apparatus of the present invention, and FIG. 6 is a sectional view of an assembly block in which the embodiment shown in FIG. 5 is made into a unit. , respectively. 10...Pressure regulating valve, 20...Inching valve,
21... Inching spool, 22... Inching rod, 23, 24... First, second spring, 25, 26, 27... Second, center, first oil chamber, 40... Selector valve, 50... Change Valve, 60...Modulator valve, C/L
1, 2...Clutch, T/C...torque converter.

Claims (1)

[Claims] 1 A hydraulic power source, a plurality of frictional engagement devices, pressure regulating valves sequentially arranged from the hydraulic power source in an oil path connecting the frictional engagement devices and the hydraulic power source, and inching control by inputting the output pressure of the pressure regulating valve. In the inching control device, the inching control device includes an inching valve that outputs pressure, and a selector valve that inputs the inching control pressure of the inching valve and selectively engages and releases the frictional engagement device. It has a first control member slidably disposed in the cylinder and a second control member separate from the first sliding member, the first control member being on one end opening side of the same diameter of the cylinder. and the first
One end of the control member protrudes from the opening and is connected to an inching pedal or a brake pedal, and the first control member has a first land portion and a second land portion slidable on the inner wall of the cylinder in a liquid-tight manner on the outer periphery of the first control member. a first elastic member is disposed between the other end of the first control member facing one end of the second control member and one end of the second control member; are disposed on the opposite side of the opening of the cylinder having different diameters, and on the outer periphery of the second control member are a third land portion, a fourth land portion, and a third land portion, which are slidable liquid-tightly on the inner wall of the cylinder. a fifth land portion and a sixth land portion, the third land portion is formed at one end of the second control member opposite to the other end of the first control member, and the fourth land portion is formed at one end of the second control member opposite to the other end of the first control member. The third land portion is formed adjacent to the third land portion and is capable of liquid-tightly sliding on a cylinder inner wall having a diameter larger than the diameter of the cylinder in which the first control member is disposed, and is defined by the third land portion. It has a first oil chamber having a first pressure receiving part of the second control member, the fifth land part is slidably formed in a cylinder having the same diameter as the fourth land part, and the sixth land part is Liquid-tight with a cylinder inner wall that is stepped from the fifth land portion, is formed at the other end of the second control member, and has a diameter larger than the diameter of the cylinder in which the fourth and fifth land portions are disposed. a second oil chamber having a second pressure receiving portion of the second control member defined by the cylinder;
between the other end of the control member and the inner wall of the cylinder
An elastic member is arranged, and a plurality of ports are connected in the cylinder, and the input ports for receiving input from the pressure regulating valve are a first input port that can be opened and closed in the first land portion, and a plurality of ports that are connected to the fourth land. a second input port that can be opened and closed at a portion thereof, and an output port that is output to the selector valve is connected to a first central oil chamber between the fourth land portion and the fifth land portion;
The second input port has a hole that can communicate with the second input port according to the movement of the fourth land portion and that constantly communicates the first central oil chamber with the first oil chamber.
formed on the control member, the first land portion and the second land portion;
A communication port is formed that communicates between a second central oil chamber between the land portions and the second oil chamber, and the communication port is connected to the second central oil chamber and responds to the movement of the first land portion. a first communication port that can communicate with the first input port; and a sixth communication port that is connected to the second oil chamber;
It has a second communication port that can open and close the land part,
Furthermore, the exhaust port that discharges to the oil pan is
The second land has at least the first exhaust port that can be opened and closed, and the fifth land has at least a second exhaust port that can be opened and closed, and when the pedal is not depressed, the first input port connects to the communication port. The second input port communicates with the output port through the oil chamber, and the second input port communicates with the output port.
The input port is closed, and the second oil chamber is communicated with the first discharge port via the communication port, and the second oil chamber is communicated with the first discharge port through the communication port.
The pressure in the oil chamber is released, and as the second input port closes, the second discharge port starts to open and the pressure in the first oil chamber is gradually reduced through the hole, and when the pedal is not depressed, , wherein the movement of the second control member urged by the pressure of the second oil chamber and the elastic force of the second elastic member is regulated by a stepped portion of the sixth land portion. Control device.