JPH02142903A - Variable capacity type hydraulic motor control circuit - Google Patents

Abstract

PURPOSE:To improve operational performance by switching a capacity control valve from a large-capacity to small-capacity, and vice versa, corresponding to the output from a detecting switch, which detects the operational force, if any, at the full-strode position of a control lever. CONSTITUTION:When an operator operates a control lever 23 of a hydraulic shovel or the like, pressure of a pressure reducing valve 25A or 25B is set via a pusher 24, while the direction of a direction switching valve 11 is switched to drive a hydraulic motor. In addition, if comparatively strong operational force is added to the system at the full-stroke position of the control valve 23, a detecting switch 26 operates. According to the signal from the switch 26, a capacity control valve 5 is switched from a small capacity side to a large capacity side, so that the hydraulic motor rotates at a low speed and high torque. On the contrary, when the operational force is lessened, the motor capacity becomes small, so that the hydraulic motor rotates at a high speed and low torque. Thus, the operational performance can be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a variable displacement hydraulic motor control circuit installed in a construction machine such as a hydraulic excavator, and in particular, the present invention relates to a variable displacement hydraulic motor control circuit installed in a construction machine such as a hydraulic excavator, and in particular, a control circuit for changing the running speed of a hydraulic excavator or the like by operating a lever. This invention relates to a variable displacement hydraulic motor control circuit with a variable displacement structure.

[Prior Art] In general, in construction machinery such as hydraulic excavators, a variable displacement hydraulic motor is used as a hydraulic motor for traveling, so that the motor capacity is reduced during low loads such as when traveling on level ground, and the hydraulic motor is operated with low torque. It rotates at high speed with high torque and rotates at low speed with high torque to provide a large capacity during heavy loads such as when climbing or carrying cargo.

Therefore, FIG. 5 shows a hydraulic circuit for a traveling device of a hydraulic excavator as an example of a conventional variable displacement hydraulic motor control circuit.

In the figure, reference numeral 1 indicates a variable displacement hydraulic motor as a traveling hydraulic motor that rotationally drives the traveling device 2. The hydraulic motor 1 may be, for example, a diagonal shaft type, a swash plate type, or a radial piston type hydraulic motor. The variable capacity part IA, such as a valve plate, swash plate or cam ring, is connected to an actuator 3, which will be described later.
By tilting and driving the motor, the motor capacity can be varied between small and large capacities.

3 indicates a variable capacity actuator (hereinafter referred to as actuator 3) attached to the hydraulic motor 1, and the actuator 3 has a small capacity side chamber 3B defined by a piston 3A and a large capacity side chamber 3C. The capacity side chamber 3C is connected to an auxiliary pump 7 or a tank 9, which will be described later, via a control line 4.
is connected to. The actuator 3 normally tilts and drives the variable capacity section IA of the hydraulic motor 1 toward the small capacity side by means of a spring 3D provided in the small capacity side chamber 3B, so that the pressure oil from the auxiliary pump 7 flows into the large capacity side chamber 3C. When the pressure oil is supplied to the chamber 3B, the piston 3A is axially slid toward the chamber 3B, and the variable capacity section IA of the hydraulic motor 1 is tilted toward the large capacity side.

5 indicates a capacity control valve provided in the middle of the control pipe 4;
The capacity control valve 5 is constituted by an electromagnetic directional control valve,
It is normally placed in the small capacity switching position (A) by a spring 5A,
When the solenoid 5B is energized via a changeover switch 15, which will be described later, the solenoid 5B is excited and switched to the large capacity switching position (b). The capacity control valve 5 switches and controls the pressure oil supplied to and discharged from the auxiliary pump 7 to the actuator 3 between the small capacity switching position (a) and the large capacity switching position (b), and controls the piston 3A of the actuator 3 in the axial direction. By sliding in the direction, the variable capacity section IA is tilted between the small capacity side and the large capacity side.

Reference numeral 6 indicates a hydraulic pump which is rotatably driven by the output shaft 8A of the prime mover 8 together with the auxiliary pump 7. The hydraulic motor 1 is rotated by supplying and discharging pressure oil to and from the hydraulic motor 1.

Reference numeral 11 indicates a directional switching valve provided in the middle of the main pipe 10A and IOB, and the directional switching valve 11 is a 4-bot, 3-position hydraulic pilot type having a pair of hydraulic pilot parts 11A and IIB on both ends. The hydraulic pilot section 11A is composed of a directional switching valve.

11B is a pilot pipe 12A branched from the control pipe 4
, 12B to the operating lever device ff113. Here, the operating lever device 13 is constituted by a pressure reducing valve type pilot valve, and applies a pilot pressure corresponding to the tilting angle (stroke amount) of the operating lever 14 to the hydraulic pilot portions 11A and IIB of the directional switching valve 11, The directional control valve 11 is moved from the neutral position (A) to the switching position (B) and (C).
It is designed to be switched to . When the directional switching valve 11 is switched from the neutral position (a) to the switching position (b), it rotates the hydraulic motor 1 in the forward direction, and when it is switched to the switching position (c), it rotates the hydraulic motor l in the reverse direction. It has become. In addition, the flow path area of the directional switching valve 11 changes depending on the tilt angle (stroke amount) of the operating lever 14, and the flow rate (
It is designed to control the amount of pressurized oil.

Further, reference numeral 15 indicates a changeover switch that is manually operated by the driver and outputs an electric signal to the capacity control valve 5.
B, and while the changeover switch 15 is OFF, the energization to the solenoid 5B is stopped, and the capacity control valve 5 is switched to the small volume 1 switching position (A) as shown in the figure.
When the changeover switch 15 is turned on, the solenoid 5B is energized and energized to switch the capacity control valve 5 from the small capacity switching position (A) to the large capacity switching position (B). .

The conventional technology is configured as described above, in which the hydraulic pump 6 is driven by the prime mover 8 together with the auxiliary pump 7, and the directional control valve 11 is moved from the neutral position (A) to the switching position (B) or (C) by the operation lever 14. When the switch is switched to , pressure oil from the hydraulic pump 6 is supplied to and discharged from the hydraulic motor 1, and the hydraulic motor 1 rotates the traveling device 2 in the forward or reverse direction to make the hydraulic excavator travel. Then, while manually operating the operating lever 14 to switch the directional control valve 11 from the neutral position (a) to the switching position (b) or (c), the directional control valve 1
1 gradually increases according to the stroke amount of the operating lever 14, the amount of pressure oil supplied from the hydraulic pump 6 to the hydraulic motor 1 also gradually increases, and the rotation speed of the hydraulic motor 1 increases as the operating lever 14 increases. Increases according to the stroke league.

In addition, the driver manually operates the selector switch 15 to turn ON and OFF.
By turning FF, the solenoid 5B of the capacity control valve 5 is energized and stopped, and when energized, the solenoid 5B is energized to switch the capacity control valve 5 from the small capacity switching position (A) to the large capacity switching position against the spring 5A. The variable capacity section IA of the hydraulic motor 1 is switched to position (B) via the actuator 3.
is tilted toward the large capacity side, and the hydraulic motor 1 is rotated at low speed with high torque.

Problem 1 to be Solved by the Invention By the way, in the above-mentioned prior art, the capacity of the hydraulic motor 1 cannot be switched between small capacity and large capacity unless the changeover switch 15 is manually turned OFF or ON. The hydraulic excavator is also provided with hydraulic motors 1 for left and right travel, and in order to rotate the hydraulic motors 1 and 1 individually, an operation lever 1 for left and right travel is provided in the driver's cab.
4.14 is provided.

Therefore, in the prior art, the left and right operating levers 14.14
If you want to switch the motor capacity while the left and right hydraulic motors 1 and 1 are being rotated by operating the left and right hydraulic motors 1 and 1, it is necessary to release your hand from at least one of the operating levers 14 and manually operate the changeover switch 15. This not only makes the operation complicated, but also makes it impossible to ensure stability when driving.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and the present invention is capable of automatically switching the capacity of a hydraulic motor from a small capacity to a large capacity by operating a control lever, thereby improving operability. The present invention provides a variable displacement hydraulic motor control circuit.

[Means to solve the problem]

A feature of the configuration adopted by the present invention in order to solve the above-mentioned problems is that different signals are sent to the operating lever device depending on whether the operating force applied to the operating lever at the full stroke position is larger than a set value or when it is smaller than a set value. A detection switch is provided to output an output, and the capacity control valve is switched between a large capacity side and a small capacity side in accordance with a signal output from the detection switch.

Further, a changeover switch for switching the capacity control valve between a large capacity side and a small capacity side may be provided in parallel with the detection switch.

Furthermore, it is preferable that the operating lever device is constituted by a pressure reducing valve type pilot valve, and the detection switch is incorporated into the pilot valve.

[Effect]

With the above configuration, when the operator applies a relatively strong operating force to the operating lever at the full stroke position, the capacity control valve is automatically switched from the small capacity side to the large capacity side by the signal output from the detection switch. This allows the hydraulic motor to rotate at low speed with high torque. Also,
If the operating force is reduced (the motor capacity is reduced),
Rotates at high speed with low torque. Furthermore, if a changeover switch is provided, the motor capacity can also be changed by manual operation as appropriate.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. In the embodiment, the same components as those of the prior art shown in FIG. 5 described above are denoted by the same reference numerals, and the explanation thereof will be omitted.

1 to 3 show a first embodiment of the present invention.

In the figure, 21 is a hydraulic pilot part 11A of the directional control valve 11.
, IIB and pilot line 12A.

As shown in FIG. 2, the operating lever device 21 is rotatably provided on the upper end side of the casing 22 and the casing 22, and the operating lever device 21 is rotatably provided on the upper end side of the casing 22, as shown in FIG. an operating lever 23 that is manually operated by a person; and an operating lever 23 built in the casing 22;
By tilting 3 to the left and 1 to the right, each button 24.24
It is generally composed of a pair of pressure reducing valves 25A and 25B whose pressure is set via the pressure reducing valves 25A and 25B.

Here, a pilot pipe 12 is connected from the pressure reducing valves 25A, 25B to the hydraulic pilot portions 11A, IIB of the directional control valve 11.
The pilot pressure output through A and 12B is controlled to be reduced according to the stroke amount (tilt angle) of the operating lever 23 as shown in the characteristic line shown in FIG.
When the pilot pressure reaches P1, the pressure becomes almost equal to the discharge pressure from the auxiliary pump 7, and the five-way switching valve 11 changes from the neutral position (A) to the left, right switching positions (B), and (H). ). Then, this pilot pressure is applied to the stroke end S2 of the operating lever 23.
The pressure is maintained at P1 until the position is reached.

Reference numeral 26.26 indicates a detection switch provided on the casing 22 of the operating lever device 21. As shown in FIG. A stopper 27 is provided on the lower surface of the stopper 27 and is connected to the power source 16 via a lead wire 28; A fixed contact 31 is fixed in the casing 22 facing the casing 22 and connected to the solenoid 5B of the capacity control valve 5 via a lead wire 30, and a movable contact 29 is connected from the fixed contact 31 to the solenoid 5B of the capacity control valve 5.
The setting spring 32 always urges the stopper 27 upward with a predetermined spring load as a setting value in order to separate the
It is composed of.

Here, the valley detection switch 26 moves the operation lever 23 to the third position.
When tilted to the full stroke position S1 shown in the figure, the cam 23A of the operating lever 23 comes into contact with the stopper 27, and when the operating force at this time is greater than the value set by the setting spring 32, the stopper 27 moves to the setting spring 32. 3, and the operating lever 23 is moved to the stroke end S2 in FIG.
When the movable contact 29 is tilted to the maximum, the fixed contact 31
come into contact with. As a result, the detection switch 26 is turned ON.
state, the solenoid 5B of the capacity control valve 5 is energized,
The capacity control valve 5 is automatically switched from the small capacity switching position (a) to the large capacity switching position (b). In addition, at other times, the detection switch 26 is in the OFF state, and the capacity control valve 5 is placed in the small capacity switching position (A) as shown.

The control circuit for the hydraulic motor 1 according to this embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art.

However, in this embodiment, the operating lever device 21 is provided with detection switches 26 that are turned on and off by tilting the operating lever 23, and the capacity control valve 5 is set to the small capacity switching position by the signal output from the valley detection switch 26. Since it is configured to switch between (A) and the large capacity switching position (B), the operator can switch the capacity of the hydraulic motor 1 from small capacity to large capacity simply by manually operating the operating lever 23.
can be automatically rotated at low speed with high torque.

That is, when the operating lever 23 is manually tilted, a pilot pressure corresponding to the stroke amount (tilting angle) at that time is generated from the operating lever device 21 as shown in the characteristic line shown in FIG. Depending on the pressure, the directional control valve 11 switches from the neutral position (a) to the switching position (b) or (c), the hydraulic motor 1 rotates at high speed with a small capacity and low torque, and the traveling device 2
The running operation is performed by. If the load acting on the hydraulic motor 1 increases when climbing up a slope, etc., the hydraulic motor 1 will not be able to perform the traveling operation smoothly.

Therefore, when the driver applies a relatively large operating force to further tilt the operating lever 23, the detection switch 26
Since the stopper 27 is pressed down against the setting spring 32, the movable contact 29 contacts the fixed contact 31, and an ON signal is output from the detection switch 26, and the solenoid 5B of the capacity control valve 5 is energized and the large The hydraulic motor 1 can now be switched to the capacity switching position (b), and the hydraulic motor 1 rotates at low speed with high torque, making it possible to perform operations such as climbing up a slope smoothly.

In particular, the driver should move the operating lever 23 to the full stroke position S.
If the running operation is slow even after tilting to I,
Normally, there is a tendency to tilt the operating lever 23 to the stroke end S2 with a stronger operating force, so it is possible to change the capacity of the hydraulic motor 1 to match this operating tendency, effectively improving operability. be able to.

Next, FIG. 4 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are given the same reference numerals, and their explanations will be omitted. , the feature of this embodiment is that the detection switch 26 (
(See FIG. 2) is provided with a changeover switch 41 in parallel. Here, the changeover switch 41 is configured in substantially the same manner as the changeover switch 15 described in the prior art, and the capacity control valve 5 is moved to the small capacity changeover position (
It is designed to switch appropriately from (a) to the large capacity switching position (b).

Thus, in this embodiment configured in this way, it is possible to obtain almost the same effects as in the previous embodiment, but in particular, in this embodiment, since the changeover switch 41 is added, the steering operation and work place can be changed easily. When the space is narrow, the capacity of the hydraulic motor 1 can be appropriately switched to a large capacity to rotate at a low speed with high torque, and the operability of the operating lever 23 etc. can be improved when making small operations.

In each of the above embodiments, the detection switch 26 has been described as being composed of a movable contact 29, a fixed contact 31, etc., but piezoelectric elements or the like may be used instead of these contacts 29, 31 and applied to the operating lever 23. An electric signal corresponding to the operating force may be output from the piezoelectric element, and the motor capacity may be switched when the output voltage exceeds a set value.

〔Effect of the invention〕

As detailed above, according to the present invention, the operating lever device is provided with a detection switch, and the capacity control valve is switched between the large capacity side and the small capacity side depending on the magnitude of the operating force applied to the operating lever. , the motor capacity can be changed simply by operating the operating lever, and when the load is heavy (the hydraulic motor can be rotated at low speed with high torque, operability can be improved, and if a changeover switch is added, The motor capacity can be fixed at a large capacity, making it easy to finely operate the control lever (
It has various effects such as:

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram, FIG. 2 is a hydraulic circuit diagram showing an enlarged view of the operating lever device, and FIG. 3 is a diagram showing the stroke amount. A characteristic diagram showing the relationship between pilot pressures, FIG. 4 is a hydraulic circuit diagram showing the second embodiment, and FIG. 5 is a hydraulic circuit diagram showing the prior art. ■...Hydraulic motor, IA...Variable capacity part, 3...
Variable capacity actuator, 5... Capacity control valve, 6...
・Hydraulic pump, 7... Auxiliary pump, 8... Prime mover,
9... Tank, IOA, IOB... Main pipe, 11.
... Directional switching valve, 12A, 12B... Pilot pipe line, 21... Operating lever device, 23... Operating lever,
25A. 25B...pressure reducing valve, 26...detection switch, 28°30 lead wire, 29...movable contact, 31...fixed contact, 41...changeover switch. Patent applicant Hitachi Keniso Co., Ltd. Agent Patent attorney Kazuhiko Hirose Diagram Stroke amount Diagram

Claims (3)

[Claims] (1) A variable displacement hydraulic motor having a variable displacement section;
A variable capacity actuator that drives a variable capacity section of the hydraulic motor, a capacity control valve that is switched between a large capacity side and a small capacity side by an external signal to control the switching of pressure oil supplied to the actuator, and a prime mover. A hydraulic pump that is driven by a hydraulic motor and supplies pressure oil to the hydraulic motor, and a hydraulic pump that is provided in the middle of a pipe connecting the hydraulic pump and the hydraulic motor, and that controls the amount of pressure oil that is supplied from the hydraulic pump to the hydraulic motor. A variable displacement hydraulic motor control circuit comprising a directional switching valve that controls and switches the rotation direction of the hydraulic motor, and an operating lever device that operates the directional switching valve,
The operating lever device is provided with a detection switch that outputs different signals depending on whether the operating force applied to the operating lever at the full stroke position is larger or smaller than a set value, and the signal output from the detection switch is A variable displacement hydraulic motor control circuit, characterized in that the displacement control valve is configured to switch between a large capacity side and a small capacity side depending on the situation. (2) The variable displacement hydraulic motor control circuit according to claim (1), further comprising a changeover switch for switching the capacity control valve between a large capacity side and a small capacity side, which is provided in parallel with the detection switch. (3) The variable displacement hydraulic motor control according to claim (1) or (2), wherein the operating lever device is constituted by a pressure reducing valve type pilot valve, and the detection switch is incorporated in the pilot valve. circuit.