JP2644307B2 - Hydraulic circuit for industrial vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit of an industrial vehicle having a flow control valve which is electrically driven and controlled.

B. Prior Art FIG. 7 shows a conventional system including a hydraulic circuit having a flow control valve driven by a pilot hydraulic pressure generated by manual operation and an engine control device.

The variable displacement main pump 1 is driven by an engine 2, and its discharge oil is guided to an actuator 4 via a pilot type flow control valve 3. Pilot pump 5
Is also driven by the engine 2 and supplies a primary pressure to the pilot valve 6. The pilot valve 6 supplies a secondary pressure proportional to the operation amount to the pilot port 3L of the pilot type flow control valve 3. The tilt angle of the main pump 1 is controlled by a regulator 7 controlled by the controller 11.
Adjusted by. The pilot type flow control valve 3
Has a pilot port 3R paired with a pilot port 3L
A manual pilot type is also connected to the pilot port 3R, but is not shown in FIG.

On the other hand, the governor 2a of the engine 2 is driven by a pulse motor 8, and the actual rotation speed of the engine 2 is detected by an engine rotation speed sensor 9 and the position of the pulse motor 8 is detected by a potentiometer 9. Then, the pulse motor 8 is controlled by a signal from the controller 11 so that the actual rotational speed of the engine 2 is controlled so that the target engine rotational speed indicated by the fuel lever 10 is achieved.

Such a system has the following problems.

For example, when the system shown in Fig. 7 is used for a hydraulic excavator, the same operation is often performed repeatedly such as excavation → turning → earth removal and horizontal retraction for leveling. , The pilot valve 6 must be operated to operate the flow control valve.

Therefore, the present applicant has proposed a device having a playback function as shown in FIG. 8 (Japanese Patent Application No. 63-45894).
issue). The same parts as those in FIG. 7 are described with the same reference numerals.

When an electric signal corresponding to the operation amount of the electric operation lever 12 is input to the controller 11, the controller 11 supplies a valve driving electric signal corresponding to the operation amount of the operation lever 12 to the proportional electromagnetic flow control valve 13. The flow control valve 13 switches by a stroke amount according to the applied electric signal, and guides the discharge oil of the main pump 1 to the actuator 4. And
The selection switch 14 is switched to the storage position, the controller 11 is set to the storage mode, and the electric operation lever 12 is operated to perform a predetermined operation, for example, excavation-turning-discharge, and store the operation procedure. Next, when the selection switch 14 is switched to the reproduction position and the controller 11 is set to the reproduction mode, and the operation start is commanded, the operation is performed according to the stored operation procedure without operating the electric operation lever 12. You. Thereby, the operator is released from the operation of the monotonous repetitive work.

By using the proportional electromagnetic flow control valve 13 as shown in FIG. 8, the following disadvantages of FIG. 7 can be solved.

That is, in the hydraulic system as shown in FIG. 7, when the load increases, the tilt angle of the main pump 1 decreases, and when the operation amount of the pilot valve 6 is constant, the actuator speed decreases and the operation feeling is poor. Therefore, the opening area of the flow control valve 3 is increased in accordance with the size of the load according to a command from the controller 11, and the flow rate to the actuator 4 is replenished by an amount corresponding to the decrease in the tilt angle, thereby suppressing the speed reduction. it can.

C. Problems to be Solved by the Invention However, in the hydraulic system of FIG. 8, if the proportional electromagnetic flow control valve 3 fails during the playback operation or the like, the control of the actuator becomes difficult, and the desired operation is not performed. .

The technical problem of the present invention is to appropriately drive and control the hydraulic actuator even when the control valve that drives the hydraulic actuator based on the electric signal from the controller fails,
Another object of the present invention is to provide a hydraulic circuit that can be stopped, and an object thereof is to increase the reliability of a hydraulic circuit for an industrial vehicle.

D. Means for Solving the Problems Referring to FIG. 1 showing one embodiment, the hydraulic circuit for an industrial vehicle according to the present invention includes hydraulic sources 1 and 5 including at least one hydraulic pump, and a pilot port 3L. Pilot type flow control valve 3 which is switched to adjust the flow rate and direction of the discharge oil of hydraulic pressure source 1 by a pilot hydraulic pressure input to
A hydraulic actuator 4 driven by pressure oil passing through the pilot type flow control valve 3; and a pilot port 3L of the pilot type flow control valve 3 by controlling the pressure of discharge oil from a hydraulic source in accordance with manual operation. A pilot pilot valve 21 which guides to a pilot port 3L of the pilot type flow control valve 3 by controlling the pressure of oil discharged from the hydraulic source 5 in accordance with an applied electric signal; The above technical problem is solved by providing the controller 11 that generates an electric signal for driving the proportional electromagnetic pilot valve 21. The manual pilot valve 6 and the proportional electromagnetic pilot valve 21 are connected in parallel or in series to the pilot port 3L.

E. Action When the pilot type flow control valve 3 malfunctions due to the failure of the proportional solenoid pilot valve 21, the disconnection of its wiring system, the superposition of noise on the wiring system, or the failure of the controller 11. In addition, the pilot flow control valve 3 can be normally driven and controlled by the manual pilot valve 6, or the pilot flow control valve 3 can be switched to the neutral position to stop the hydraulic actuator 4. Therefore, the reliability of this type of hydraulic system is improved.

In the above sections D and E for describing the configuration of the present invention, the drawings of the embodiments are used for easy understanding of the present invention, but the present invention is not limited to the embodiments.

F. Embodiment -First Embodiment- A first embodiment in which the present invention is applied to a hydraulic system of a hydraulic shovel having a playback function will be described with reference to FIGS. 1 and 2. The same parts as in FIG. 7 will be described with the same reference numerals.

Between the pilot port 3L of the pilot type flow control valve 3 and the pilot pump 5, the above-mentioned manual type pilot valve 6 and proportional electromagnetic type pilot valve 21 are connected in parallel. As will be described later, the proportional electromagnetic pilot valve 21
The operation amount is controlled according to the valve driving electric signal supplied from the controller 11, and the primary pressure is reduced according to the valve driving electric signal. That is, the manual pilot valve 6
Similarly, the secondary pressure is output in proportion to the manipulated variable.

Pressure sensor 22 detects a pilot pressure to pilot port 3L, and inputs a detection signal to controller 11. As described above, the selection switch 14 is switched between the storage position, the neutral position, and the reproduction position, stores a predetermined work procedure at the storage position, and reproduces the stored work procedure at the reproduction position. A valve drive electric signal is applied to the valve 21. Note that the pilot type flow control valve 3 has a pilot port 3R paired with the pilot port 3L. The manual type pilot valve 6 and the proportional solenoid type pilot valve 21 are also connected in parallel to the pilot port 3R. Illustration is omitted in the figure.

 The operation of the embodiment configured as described above will be described.

-When an abnormal operation occurs-For example, when the proportional electromagnetic pilot valve 21 fails and the actuator 4 operates abnormally, the operator can manually operate the manual pilot valve 6 to control the actuator 4. That is, if the manual pilot valve 6 is controlled so that the secondary pressure of the manual pilot valve 6 becomes higher than the secondary pressure of the proportional electromagnetic pilot valve 21, the pilot flow rate control valve 3 becomes the high pressure side pressure. Since the switching is controlled, the actuator 4 can be appropriately controlled.

-Storage mode-When storing the work procedure, the selector switch 14 is switched to the storage position, the controller 11 is set to the storage mode, and the manual pilot valve 6 performs predetermined work, for example, excavation → turning → earth removal. Do. At this time, the secondary pressure of the manual pilot valve 6 is detected by the pressure sensor 22, and a corresponding electric signal is input to the controller 11. The controller 11 stores the time change of the electric signal and stores a predetermined work operation.

-Playback mode-Switch the selection switch 14 to the playback position and
Set to playback mode. In this regeneration mode, the stored time variation of the pilot pressure is read out, and the valve driving electric signal V corresponding to the pilot pressure is reproduced for a predetermined time (FIG. 2 (b)). Output to the valve 21. Thus, the stored work procedure, that is, excavation → turn → discharge, is performed without operating the manual pilot valve 6.

FIG. 2A shows a flowchart executed by the controller 11 in the storage mode and the reproduction mode.

In addition, the selection switch 14 is used as an on / off switch,
When on, the mode is such that the opening area of the flow control valve 3 is controlled according to the load, and the present invention can be applied to a hydraulic system in which the opening area is controlled according to the flowchart of FIG.

That is, when the selection switch 14 is turned on, in step S13, the valve driving electric signal V (FIG. 3 (b)), which increases as the tilt angle q of the main pump 1 decreases, is supplied to the proportional electromagnetic pilot valve 21. As a result, the opening area of the flow control valve 3 is increased by an amount corresponding to the decrease in the discharge flow rate of the main pump 1 due to the load, and the speed reduction of the actuator 4 is suppressed. Also in such a hydraulic system, the flow control valve 3 can be appropriately controlled by operating the manual pilot valve 6 when the proportional electromagnetic pilot valve 21 fails.

Second Embodiment For example, in a hydraulic excavator, there are various types of work requiring fine operation and rapid operation, and it is required that the metering characteristics of the flow control valve 3 be adjusted in accordance with the work. However, the metering characteristics of the flow control valve 3 could not be adjusted. For this reason, a method of controlling the tilt angle of the main pump 1 by a controller is known.
It does not adjust the metering characteristics of the flow control valve 3 and cannot know the optimal metering characteristics for the working mode. Therefore, in the second embodiment, the change characteristic of the pilot pressure with respect to the operation amount of the manual pilot valve 6 can be variously selected according to the work form, and the metering characteristic of the pilot flow control valve 3 is adjusted in a pseudo manner. Thus, the operability is improved.

A second embodiment will be described with reference to FIGS. The same parts as in FIG. 7 will be described with the same reference numerals.

In this embodiment, a manual pilot valve 6 and a proportional electromagnetic pilot valve 21 are connected in series between a pilot pump 5 and a pilot port 3L of the pilot type flow control valve 3, and the mode switch 31 The operation mode I, the fine operation mode II and the fine operation mode III can be selected, and the characteristics of the pilot pressure P and the voltage V applied to the proportional electromagnetic pilot valve 21 are changed according to each mode as shown in FIG. Is set to In the second embodiment, the above-described playback function is executed by operating the selection switch 14.

When the sudden operation mode I is set by the mode switch 31, the controller 11 supplies the maximum applied voltage Vmax to the proportional electromagnetic pilot valve 21. Accordingly, the proportional electromagnetic pilot valve 21 outputs the primary pressure as it is as the secondary pressure, and as shown by the characteristic I in FIG. 5 (b), the secondary pressure corresponding to the operation amount of the manual pilot valve 6 Is a pilot port
Guided to 3L. Therefore, if the manual pilot valve 6 is suddenly operated, the actuator 4 can be rapidly operated.

When the fine operation mode II is set by the mode switch 31, the controller 11 supplies the minimum applied voltage Vmin to the proportional electromagnetic pilot valve 21. Thereby, as shown by the characteristic II in FIG. 5 (b), the secondary pressure according to the operation amount of the manual pilot valve 6 is further increased by the proportional electromagnetic pilot valve.
The pressure is reduced according to the pressure reducing characteristics of 21 and guided to the pilot port 3L. As a result, even if the manual pilot valve 6 is suddenly operated, the change in the pilot pressure with respect to the operation amount is smaller than in the sudden operation mode I, and the fine operation is possible.

Further, when the fine operation mode III is set by the mode switch 31, as shown in the characteristic III of FIG. 5 (c), the controller 11 applies the applied voltage Vp corresponding to the pilot pressure detected by the pressure sensor 22 to the proportional electromagnetic pilot. Supply to valve 21. Thereby, as shown by the characteristic III in FIG. 5 (b), it can be obtained in accordance with the operation amount of the manual pilot valve 6 and the pressure reduction characteristic that changes depending on the pilot pressure of the proportional electromagnetic pilot valve 21. The pilot pressure P is led to the pilot port 3L. As a result, the manual pilot valve 6
When the operation amount is small, the pilot pressure change with respect to the operation amount is small as compared with the case where the manual pilot valve 6 alone is used, and even if the operation amount is suddenly operated, fine operation is possible.

FIG. 5C shows a flowchart for executing the above operation.

Even in the hydraulic system having the above configuration, even if the proportional electromagnetic pilot valve 21 fails,
The pilot type flow control valve 3 can be controlled by the above operation, so that a highly reliable system can be provided.

In the hydraulic system shown in FIG. 4, even if the positional relationship between the manual pilot valve 6 and the proportional electromagnetic pilot valve 21 is reversed as shown in FIG. 6, exactly the same effect can be obtained.

Although the present invention has been described above with respect to the excavator, the present invention can be applied to construction machines and industrial vehicles other than the excavator.

G. Effect of the Invention According to the present invention, a hydraulic pilot type flow control valve disposed between a hydraulic actuator and a hydraulic source is output from a pilot hydraulic pressure output from a proportional electromagnetic pilot valve or output from a manual pilot valve. The pilot hydraulic pressure can be controlled, so if the proportional electromagnetic pilot valve driven by an electric signal breaks down, or if the power supply line or signal line breaks or shorts, and the pilot type flow control valve operates abnormally, Since the hydraulic actuator can be operated normally or the hydraulic actuator can be stopped by the pilot hydraulic pressure from the pilot valve, the reliability of this type of hydraulic system is improved.

[Brief description of the drawings]

FIG. 1 and FIG. 2 illustrate the first embodiment.
FIG. 1 is a block diagram showing the overall configuration, FIG. 2A is a flowchart for executing various modes, and FIG. 2B is a diagram showing a reproduced waveform of an applied electric signal. FIG. 3 shows a modification of the first embodiment, in which (a) is a flowchart, and (b) is a graph of the tilt angle and the applied electric signal. 4 and 5 illustrate the second embodiment.
FIG. 4 is a block diagram corresponding to FIG. 1, FIG. 5 (a) is a graph of an applied electric signal with respect to a pilot pressure, and (b)
Is a graph showing the operation amount of the manual pilot valve and the pilot pressure, and (c) is a flowchart. FIG. 6 is a block diagram showing a modification of the second embodiment. 7 and 8 are hydraulic circuit diagrams showing a conventional example. 1: Main pump, 2: Engine 3: Pilot type flow control valve 3L: Pilot port 4: Hydraulic actuator 5: Pilot pump 6: Manual pilot valve 7: Pump regulator 11: Controller, 14: Select switch 21: Proportional solenoid Pilot valve 22: Pressure sensor, 31: Mode switch

Claims (3)

(57) [Claims] A hydraulic pressure source including at least one hydraulic pump; a pilot-type flow control valve that switches to adjust a flow rate and a direction of a discharge oil from the hydraulic source by a pilot hydraulic pressure input to a pilot port; A hydraulic actuator driven by pressure oil passing through the flow control valve, and a manual pilot valve that controls the pressure of the discharge oil from the hydraulic source in accordance with manual operation and guides the pressure to the pilot port of the pilot flow control valve. A proportional electromagnetic pilot valve that controls the pressure of the discharge oil from the hydraulic pressure source in accordance with the applied electric signal and guides the pressure to the pilot port of the pilot flow control valve; and a controller that generates the electric signal. Hydraulic circuit for an industrial vehicle. 2. The hydraulic circuit according to claim 1, wherein said manual pilot valve and said proportional electromagnetic pilot valve are arranged in parallel with said pilot port. circuit. 3. The hydraulic circuit according to claim 1, wherein the manual pilot valve and the proportional electromagnetic pilot valve are arranged in series with the pilot port. circuit.