JPH0553950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an improvement in a backup device in the event of failure of an electro-hydraulic pump regulator that electrically controls the discharge amount of a variable displacement hydraulic pump.

[Background of the invention]

FIG. 2 is a circuit diagram showing the basic configuration of a conventional hydraulic drive device.

In the figure, 1 is a variable displacement hydraulic pump, 2 is a hydraulic actuator connected to the hydraulic pump 1, and 3 is a hydraulic actuator connected to the hydraulic pump 1.
is the load operated by hydraulic actuator 2,
4 is a discharge amount control mechanism of the hydraulic pump 1, which includes a housing 4a, an actuator 4b housed in the housing 4a and tilting the swash plate of the hydraulic pump 1, solenoid valves 4c and 4d, and a discharge amount control mechanism of the hydraulic pump 1. A discharge amount detector that detects the amount and outputs a discharge amount signal Q _p , that is, a displacement meter 4e that detects the displacement of the swash plate.
It is equipped with Reference numeral 5 indicates a command signal Qo' for controlling the discharge amount control mechanism 4 of the hydraulic pump 1 through electromagnetic valves 4c and 4d.
6 is an operation lever that outputs a target discharge amount signal Qo to the discharge amount control device 5;
7 is a pressure detector that detects the pressure of the hydraulic pressure discharged from the hydraulic pump 1 and outputs a pressure signal P to the discharge amount control device 5; 8 is a hydraulic pressure source; 9 is a tank; 10 is the hydraulic pump 1; and a hydraulic cylinder. 2, and 11 is a power source connected to the discharge amount control device 5.

FIG. 3 is an explanatory diagram showing the basic configuration of the discharge amount control device 5 provided in the hydraulic drive device shown in FIG. 2. FIG. This discharge amount control device 5 is composed of a microcomputer, and includes a central processing unit 5a, a 1/0 interface 5b for output, and amplifiers 5c and 5d connected to the solenoid valves 4c and 4d in FIG. ,
a memory 5e that stores a control procedure program;
It is equipped with an A/D converter 5f that converts analog signals of the target discharge amount signal Qo, pressure signal P, and discharge amount signal Qp output from the device lever 6, pressure detector 7, and displacement meter 4e, respectively, into digital signals. .

This discharge amount control device 5 receives a target discharge amount signal Qo from a device lever 6, a pressure signal p from a pressure detector 7,
The drive command value of the hydraulic pump 1 is calculated based on the control procedure program, and the command signal Qo' is sent to the solenoid valve 4.
c, 4d, and the discharge amount signal Qp, which is the output of the displacement meter 4e, is the command signal.
It is controlled by an on-off servo, which is an example of an electric-hydraulic servo, so as to be equal to Qo'.

This on/off servo is performed as follows. That is, as shown in FIG. 2, the area of the left chamber 4f forming both sides of the actuator 4b is larger than the area of the right chamber 4g. The left chamber 4f is connected to a hydraulic power source 8 through a solenoid valve 4c, and is connected to a tank 9 through a solenoid valve 4d, and the right chamber 4g is directly connected to a hydraulic power source 8. Therefore,
When the solenoid valve 4c is energized, the left chamber 4f is communicated with the hydraulic power source 8, and the actuator 4b is moved to the right in the figure due to the area difference.When the solenoid valve 4c is demagnetized, the actuator 4b is held stationary;
When d is excited, the actuator 4b moves to the left due to the pressure in the right chamber 4g. This combination of movements is performed every very small period, that is, every sampling period.

By the way, in the above-mentioned electro-hydraulic pump regulator, if the discharge amount control device 5, the displacement meter 4e, or the solenoid valves 4c and 4d are out of order, it becomes impossible to control the discharge amount of the hydraulic pump 1. , the actuator 4b is held at a position where the maximum discharge amount corresponds to the left side chamber 4f or the right side chamber 4g, and the maximum discharge amount corresponds to the minimum discharge amount.

Therefore, when this device is applied to a hydraulic excavator,
If the above-mentioned failure occurs, the discharge amount of the hydraulic pump 1 will be at the maximum or minimum, but the product of the maximum discharge amount and the maximum pressure of the hydraulic excavator is set to be more than twice the output of the installed prime mover. Generally speaking, if the maximum flow rate is reached due to a failure, the load will exceed the prime mover output and operation will no longer be possible. In addition, the minimum flow rate of the hydraulic pump 1 is generally set close to zero in order to control the pump discharge amount so that the circuit does not exceed the set pressure of a relief valve (not shown) and to prevent energy loss. Therefore, if it reaches the maximum flow position at the time of failure, it becomes impossible to drive the vehicle.

Therefore, as shown in FIG. 4, in the housing 4a to which the backup device is attached, a right chamber 4g on the small diameter side is located at a stroke S of the actuator 4b corresponding to the discharge amount of the hydraulic pump 1 in an emergency.
A passage 4i is formed, and a passage 4h is further formed on the left side thereof. A sliding portion having a length l is provided on the small diameter side of the actuator 4b so that the passages 4h and 4i can be closed almost simultaneously. The solenoid valve 14 is normally demagnetized, and the passages 4h, 4i and the left chamber 4f are closed.

Now, when the electrohydraulic pump regulator malfunctions and the solenoid valve 14 is energized by the switch 13, the passages 4h, 4i and the left chamber 4f become conductive. In this state, when the actuator 4b comes to the right side of the stroke S, the passage 4i is closed and the passage 4h
communicates with tank 9. Therefore, the pressure in the left chamber 4f decreases, and the pressure of the hydraulic source 8 is applied to the right chamber 4g, so the actuator 4b moves to the left. On the other hand, when the actuator 4b moves to the left of the stroke s, the passage 4h is closed and the passage 4i communicates with the hydraulic source 8, so the left chamber 4f becomes under the pressure of the hydraulic source 8, and due to the difference in area of the actuator 4b, Move the actuator 4b to the right. This operation causes the actuator 4b to be held at the stroke S position.

FIG. 5 shows different backup devices. A passage 4j is formed in the housing 4a, and a sliding portion for closing the passage 4j is formed in the actuator 4b, so that the stroke S of this closing becomes the discharge amount of the hydraulic pump 1 in an emergency. In an emergency, the solenoid valve 14 is energized and the passage 4j and left side chamber 4 are
f is communicated. Actuator 4
If b is on the right side of stroke S, passage 4j
communicates with the tank 9, the pressure in the left chamber 4f decreases, and the actuator 4b moves to the left. On the other hand, when the actuator 4b is on the left side of the stroke S, the passage 4j communicates with the hydraulic source 8, the left chamber 4f has the same pressure as the hydraulic source 8, and the area difference moves the actuator 4b to the right. In this way,
The actuator 4b is maintained at a position where the sliding portion closes the passage 4j, that is, at a stroke of a preset discharge amount.

FIG. 6 shows a still different conventional backup device, in which a passage 4s is formed in the housing 4a on the left chamber 4f side, which is the larger diameter side of the actuator 4b. This passage 4s is designed to be closed by the actuator 4b at the position of the discharge amount of the hydraulic pump 1 in an emergency, and is constantly communicated with the tank 9. A passage 4r is formed near the passage 4s of the housing 4b.
It communicates with These passages 4s and 4r are closed by a plate 4t during normal operation, but are configured to communicate as shown in the figure in an emergency.
Therefore, the plate 4t has the same function as the solenoid valve 14 shown in FIGS. 4 and 5.

Now, when the actuator 4b closes the passage 4s, the pressure of the hydraulic source 8 reaches the left chamber 4f via the 4p, and the actuator 4b is driven to the right. Then, the passage 4s is opened and the left side chamber 4f communicates with the tank 9, so the oil on the hydraulic face is 8p.
It flows into tank 9 via. Therefore, a pressure drop occurs due to the ridge 4p, and the pressure in the left chamber 4f decreases, and the actuator 4b is driven to the left by the force from the small diameter chamber 4g. In this way, the actuator 4b operates on the left side chamber 4, which is made up of the pressure balance between the ridge 4p and the passage 4s formed by the actuator 4b.
It is held at a position where the force f and the force of the small diameter chamber 4g are balanced. This position is the position of the pump discharge amount in an emergency.

FIG. 7 shows a further different example of the conventional backup device.

The actuator 40b has the same area on both the left and right sides, and the details are shown in Japanese Patent Application No. 57-41674.

In such a configuration, a passage 40m is provided on the right chamber 40g side of the housing 40a as in the embodiment shown in FIG. The stroke is the pump discharge amount in case of emergency. At this time, the sliding portion 401b of the actuator 4b also closes the passage 40n. In addition, the solenoid valves 40d and 40k are normally open, which communicates with the hydraulic power source in a demagnetized state, and the solenoid valves 40c and 40k are normally open.
40L uses a normally closed system that cuts off communication to the tank in a demagnetized state. In addition, the hydraulic power source 8 and the right chamber 4
Between 0g and left ventricle 40f there is a ridge 40g, 4
Set 0p. Passages 40m and 40n have cutoff valves 14
In step 1, the electro-hydraulic servo is disconnected when it is normal and connected when it is abnormal.

In case of abnormality, solenoid valves 40c, 40b, 40k, 4
All of 0l is demagnetized, and the oil pressure of hydraulic source 8 is activated.
It is led to the left chamber 4f and the right chamber 40g via 0p and 40q. The switching valve 141 has passages 40n and 40m.
communicate between. Now, if the actuator 40b is on the right side of the stroke S, the passage 40m is the tank 9.
The passage 40n is connected to the left chamber 40f. Therefore, the oil pressure in the left chamber 40f is changed to the switching valve 141.
and flows into tank 9. However, since there is a ridge 40p between the hydraulic source 8 and the left chamber 40f, the pressure in the left chamber 40f decreases, and the pressure in the right chamber 40g remains the same as that of the hydraulic source 8, so the actuator 40
b moves to the left. On the contrary, actuator 40b
is to the left of the stroke S, the right ventricle 40
g passes through the passage 40m, the switching valve 141, and the passage 40n and communicates with the tank 9. Therefore, the pressure in the right chamber 40g decreases due to the curvature 40q, and the actuator 40b moves to the right. In this way, the actuator 40b is held at the position where it closes the passages 40m and 40n, that is, at the stroke S.

In the above-mentioned backup device, the position of the actuator is maintained at a predetermined position in any of the embodiments, so that it is possible to prevent the discharge amount from reaching the maximum or minimum discharge amount as in the conventional case. However, since the actuator is always held at a predetermined position, the discharge amount cannot be increased, for example, under light load conditions, resulting in a reduction in work efficiency.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a backup device for an electrohydraulic pump regulator that can control the discharge amount to improve work efficiency.

[Summary of the invention]

The present invention is characterized in that even when a failure occurs and the backup device is activated, the discharge amount of the hydraulic pump can be adjusted within a predetermined range.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a hydraulic circuit diagram showing a backup device of an electro-hydraulic pump regulator, in which 15 is a lever, 16 is a housing 4a and an actuator 4b.
A sleeve is slidably fitted between the lever 15 and connected to the lever 15. This sleeve 16 has
Passages 16h and 16i are formed which are closed almost simultaneously by a sliding portion having an axial length l of the actuator 4b. 4j and 4k are passages formed between the sleeve 16 and the housing 4a, and the actuator 4b
Stroke from the minimum flow position to the maximum flow rate l ₁
It has a considerable width. 4s and 4t are passages 4j,
4k and the solenoid valve 14. Components in this figure that are equivalent to those in FIG. 4 are given the same reference numerals.

Normally, the solenoid valve 14 is demagnetized, and the passages 4s and 4t of the housing 4a and the left chamber 4f are in a closed state.

Now, the electro-hydraulic pump regulator has broken down, and the switch 13 causes the backup device's solenoid valve 14 to
When excited, the passages 4s, 4t and the left chamber 4f
The space becomes connected. The actuator 4b is driven to the right due to the difference in pressure receiving area, and when its sliding portion closes the passage 16i, the passages 4s, 4t, and 16h communicate with the tank 9. Therefore, the pressure in the left chamber 4f decreases, and on the other hand, the pressure oil from the hydraulic source 8 is applied to the right chamber 4g, so the actuator 4b is driven to the left where the tilting angle increases. When the actuator 4b is driven to the left, the passage 16h is closed and the passage 16i is communicated with the hydraulic power source 8, so the left chamber 4f has the solenoid valve 14, the passage 4t, the passage 4k, the passage 16i,
The pressure becomes the pressure of the hydraulic pressure source 8 via the right chamber 4g. As a result, the actuator 4b is driven to the right where the tilting angle is small due to the pressure receiving area difference. In this way, the actuator 4b is connected to the passages 16h, 16
It is held between i.

When such a backup device is operated, the lever 15 is operated according to the load on the hydraulic pump 1. This operation allows the position of the sleeve 16, that is, the passage 16, to be adjusted without changing the hydraulic communication relationship described above.
The holding position of the actuator 4b can be adjusted based on the positions of h and 16i. This position change is determined by the width of the passages 4j and 4k,
Since this width is approximately equal to the maximum flow rate position to the minimum flow rate position of the actuator 4b, the actuator 4b can be held at any position within this range.

Although the above embodiment is based on the configuration shown in FIG. 4, which was explained as a conventional example, the backup devices shown in FIGS. The distance between the sleeve passage, which is dynamically inserted and whose opening/closing is controlled by the sliding part of the actuator, and the passage of the housing connected to the solenoid valve is set to a predetermined width, for example, from the maximum flow position of the actuator to the minimum flow rate. A similar effect can be obtained by communicating through passages 4J and 4K having a certain width.

Note that the passages 4J and 4K shown in FIG.
Sleeve 16 of housing 4s connected to s, 4t
Although the passages 16h and 16i are formed on the housing side of the sleeve 16, they may be formed on the housing side of the sleeve 16, or may be formed on both sides.

〔Effect of the invention〕

As explained above, the present invention includes a sleeve slidably inserted between an actuator and a housing,
Since the passages in the sleeve and the housing are communicated through a passage with a predetermined width, by adjusting the position of the sleeve according to the load of the hydraulic pump, the holding position of the actuator can be adjusted and the backup device can be activated. Even at times, the discharge flow rate can be adjusted to increase operating efficiency.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of a backup device according to an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram of a conventional electro-hydraulic regulator, FIG. 3 is a configuration diagram of the discharge amount control device of FIG. 2, and FIG. 7 to 7 are hydraulic circuit diagrams of different conventional backup devices. 1... Variable displacement hydraulic pump, 4a... Housing, 4b... Actuator, 4f... Left side chamber,
4g...Right side chamber, 4J, 4K...Aisle, 4s, 4
t...Passage, 14...Solenoid valve, 16...Sleeve, 16h, 16i...Passage.

Claims (1)

[Claims] 1. An actuator that controls the discharge amount of a variable displacement hydraulic pump, a housing that houses the actuator, and an electromagnetic valve connected to a passage formed in the housing corresponding to a sliding part with the actuator, In the backup device for an electrohydraulic pump regulator, the electrohydraulic pump regulator is configured to actuate the electromagnetic valve in the event of an abnormality to hold the actuator at a predetermined position corresponding to the passage, wherein: between the sliding part of the actuator and the housing; A position-adjustable sleeve is inserted, and a passage formed in the sleeve for controlling the sliding portion and a passage in the housing are communicated by a passage having a predetermined width in the position adjustment direction of the sleeve. A backup device for an electro-hydraulic pump regulator.