JPS5922074B2 - Variable displacement hydraulic pump and hydraulic system using the hydraulic pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable displacement hydraulic pump and a hydraulic system using the hydraulic pump.

In a conventional hydraulic circuit, when controlling a hydraulic pump to supply the required pressure oil into the circuit, the controller or servo motor that regulates the tilting angle of the hydraulic pump, that is, the pump angle, is a manual or remote control valve. etc., to artificially control the flow rate, or by the pump discharge pressure,
Self-pressure control of the tilting angle was performed.

For this reason, when the load changes or the required flow rate changes, energy loss is large, and in order to reduce this, the flow rate and pressure settings must be changed artificially, which is extremely difficult. In addition to being time-consuming, it was difficult to change the flow rate accurately and efficiently.

The present invention has been made in view of the above points, and its purpose is to provide a variable displacement hydraulic pump that automatically adjusts the pump angle using a control mechanism to reduce energy loss, and a hydraulic system using the hydraulic pump. is to provide.

The variable displacement hydraulic pump according to the present invention has a main body for controlling the pump angle of the hydraulic pump, two pressure chambers, first and second pressure chambers, which are arranged opposite to each other to operate the main body, and one pressure chamber. a control plate that operates in relation to the pressure in the chamber; a first spring provided between the control plate and the main body;
The control device includes another second spring that presses the control plate toward the second pressure chamber, and has a bypass valve that drains the discharge pressure in conjunction with the main body.

Further, the hydraulic device according to the present invention includes a main body portion that controls the pump angle of the variable displacement pump, and two pressure chambers, first and second pressure chambers, arranged oppositely to operate the main body portion.
A control plate that operates in relation to the pressure in one of the second pressure chambers, a first spring provided between the control plate and the main body, and a control plate that presses the control plate toward the second pressure chamber. It has a variable displacement hydraulic pump equipped with a control device consisting of another second spring, and the control device is provided with a bypass valve that is connected to the discharge line in conjunction with the main body and unloads the discharge pressure. , a plurality of actuators connected in parallel driven by pressure oil from the hydraulic pump, and a comparator for comparing the oil pressure of each actuator, and the discharge pressure of the hydraulic pump is transferred to a first pressure chamber of the main body. and a second pressure transmission line that converts electrical or pressure signals from the comparator into pressure and transmits the converted signals to the second pressure chamber of the control board. .

Therefore, when all the actuators are stopped, that is, when the switching valve is in the neutral position, the pressure of the high pressure line is applied to the first pressure chamber, the bypass valve is switched, the high pressure line is drained, and the hydraulic pump is turned off. loaded.

In addition, when the actuator operates, the highest pressure among the multiple actuators that are operating is introduced into the second pressure chamber, and that pressure presses another second spring, thereby causing the connection between the main body and the control board. A first spring provided therebetween is compressed.

The first spring pressing on its body is therefore controlled by the load and the total flow rate required for each actuator is controlled by the first spring pressing on its body determining the pump angle of the pump.

By doing so, the difference between the maximum pressure of the actuator and the circuit pressure (pump discharge pressure) can be reduced, and therefore the energy loss of the variable displacement hydraulic pump can be reduced.

Embodiments of the variable displacement hydraulic pump and hydraulic system according to the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a variable discharge amount pump. The pump 1 sucks oil from a tank T and supplies pressure oil to a high pressure line 4 via a discharge line 2 and a check valve 3.

An actuator (not shown) is connected to the high pressure line 4 via a variable throttle valve or pressure compensator 5, a line 6, a directional valve I, and a line 8 or 9, and the drain oil from the actuator is drained from the line 8 or 9, is returned to the tank T via the directional control valve 11 and the low pressure line 10.

Similarly, one or more other actuators (not shown) are connected to the high pressure line 4 and can be driven by oil discharged from the pump 1.

11 is a pump angle control device for the pump 1, and this pump angle control device 11 has a main body portion 15, first and second springs 12 and 13, and a control plate 14.

The first spring 12 is provided between the control plate 14 and the main body 15, and the second spring 13 presses the control plate 14 toward the second pressure chamber 17.

Force F of spring 13.

is much greater than the force F1 of the spring 12, and this control plate 14 receives the pressure P from the pressure transmission line 16.

is moved by applying this to the second pressure chamber 17.

Further, a bypass valve 25 is provided on the opposite side of the control device 110, and this bypass valve 25 works in conjunction with the main body 15 to transfer the pressure Ps from the °C high pressure line 4 to the first pressure chamber via the first pressure transmission line 26. 19.

20 is a comparator connected to lines 27, 21 and 22, which detects the pressure of each actuator, selects the highest pressure in each actuator, and sends the highest pressure signal (hydraulic or electric) to the converter 30. , and signal P.

As mentioned above, the second
The pressure chamber 17 is guided to the pressure chamber 17.

23 is an accumulator attached to the high pressure line 4, 24
is a variable throttle valve provided between line 4 and line 16.

A converter 30 is connected to the line 27, and this converter 30 receives a signal (hydraulic or electric) from the line 27 and a hydraulic signal from the throttle 24 and converts it into a hydraulic signal PC.

Therefore, line 21 may be an electrical signal instead of a hydraulic signal.

The present invention is constructed as described above, and its operation will be described first. When each actuator is stopped, the switching valve 7 is in the neutral position and is blocked, so the high pressure line 4 pressure increases.

This pressure is guided to the first pressure chamber 19 of the control device 11,
When this pressure increases to 1 which overcomes the opposing spring 12, the hydraulic pump 1 is controlled to the minimum discharge position, the bypass valve 25 is switched, and the hydraulic pump 1 is unloaded.

At this time, the high pressure life 40 circuit pressure Ps is maintained by the check valve 3 and the accumulator 23.

Next, when the switching valve 7 is operated to operate each actuator, the highest pressure Pc in each accumulator is selected by the comparator 20, and that pressure is applied to the second
pressure chamber 17, presses the second spring 13 via the control plate 14, determines the position of the control plate 14, and sets the first spring 12.

Therefore, the pressure in the first pressure chamber 19 and the first spring 12
The position of the main body portion 15 is determined by the zero comparison, and the discharge amount of the hydraulic pump is determined.

That is, depending on the maximum load at that time, the second spring 1
3 is set, and each actuator has a required flow rate (total required flow rate of each actuator) corresponding to the required circuit pressure ps at that time, and the required flow rate (total required flow rate of each actuator) is also adjusted to the pump angle α set by the action of the first spring 12. It is supplied as follows.

The circuit pressure ps at this time and the maximum pressure PC of the actuator
By making P s-P C as small as possible as shown in FIG. 2, the energy loss of the hydraulic pump can be reduced.

Next, a manner in which the pump tilting angle α, that is, the pump discharge amount is controlled by opening and closing the valve 5, will be described.

When the second spring 13 is compressed by the pressure pc and the position of the control plate 14 is determined, the amount of compression of the first spring 12 is also determined.

That is, the position of the control plate 14 is determined in relation to the pressure PC.

The relationship between the pressure ps in the first pressure chamber 19 and the pump tilting angle α is set by the spring force F1 proportional to the amount of compression of the first spring 12.

In FIG. 3, lines A 1 , A2 , -A3 and A4 respectively correspond to the value of pressure pc, that is, the position of control plate 14 when the position of control plate 14 fluctuates due to pressure PCK, and the ℃ pressure ps This is a characteristic line showing the relationship between the pump tilt angle α and the pump tilt angle α.

Now, the expansion and contraction of the first spring 12: 'From this, the pressure ps
It is assumed that the relationship between and the pump angle α is set to the characteristic shown by line A3 in FIG.

When the valve 5 is moved in the closing direction, the unnecessary flow rate is throttled and the pressure ps increases because the valve 5 is equipped with pressure compensation.

As a result, the tilt angle a decreases on the line A3 (the third direction).
(in the upper left direction in the figure), and the pump discharge amount decreases.

Then, the angle α is balanced and fixed at the point on the line where the unnecessary flow rate part is eliminated (the point at the angle α corresponding to the required flow rate).

The pressure ps is approximately equal to the maximum load pressure (the highest pressure in each line 6) and the sum of the loss pressures of the child valves 5 and 7.

If the relationship between the pressure Ps and the pump tilt angle α, that is, the ps-α line, is designed to be nearly horizontal as shown by the middle lines A1 to A4 in FIG. However, the pump tilting angle α moves along the ps-α line corresponding to the value of the pressure pc.

Therefore, the rise in pressure Ps is small, and the pressure difference ps-pc
The flow rate required by the pressure compensator 5 (
The pump angle σ is controlled according to the total flow rate of the opening of the joint valve 5).

Note that the pressure difference ps-pc is determined by valves 3, 5, . '), the required minimum pressure is determined from the loss pressure at the maximum flow rate of valves such as 7, piping loss pressure, etc.

As described above, in the present invention, when driving a plurality of actuators with one variable displacement hydraulic pump, the required total flow rate and the required maximum pressure of each actuator are always detected and controlled.

That is, the pressure setting of the pump angle control device 11 is controlled by the second spring 1 using the self-discharge pressure of the variable displacement hydraulic pump.
3, and the control device 11 is actuated by the pressure of the first spring 12 and the first pressure transmission line 26 so that the discharge flow rate of the pump becomes the total flow rate of the actuator.

Therefore, according to the present invention, the discharge amount and pressure of a variable displacement hydraulic pump can be continuously detected and automatically adjusted according to the usage status of the hydraulic system, without the need for complicated manual operations, and in a reliable manner. The pump discharge amount can be quickly and appropriately changed, and energy loss can be reduced.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of a hydraulic pump and hydraulic system according to the present invention. FIG. 2 is an explanatory diagram of energy loss in the hydraulic pump according to the present invention, and FIG. 3 is a diagram showing the relationship between high pressure line pressure and pump tilt angle. 1... Hydraulic pump, 4... High pressure line, 11... Control device, 16, 26...
Pressure transmission line, 25...Bypass valve, 20.
...Comparator.

Claims (1)

[Claims] 1. A main body for controlling the pump angle of a variable displacement pump, two pressure chambers, first and second pressure chambers, arranged oppositely to operate the main body; A control plate that operates in relation to the pressure of the second pressure chamber, a first spring provided between the control plate and the main body, and another spring that presses the control plate toward the second pressure chamber. What is claimed is: 1. A variable displacement hydraulic pump, comprising: a control device comprising two springs; and a bypass valve that unloads discharge pressure in conjunction with the main body of the pump. 2. A main body that controls the pump angle of a variable displacement pump, two pressure chambers, first and second, arranged oppositely to operate the main body, and the pressure in one of the second pressure chambers. It consists of a control plate that operates in conjunction with the control plate, a first spring provided between the control plate and the main body, and another second spring that presses the control plate toward the second pressure chamber. It has a variable displacement hydraulic pump equipped with a control device, and the control device is provided with a bypass valve that is connected to the discharge line of the hydraulic pump in conjunction with the main body and unloads the discharge pressure, and the control device is provided with a bypass valve that unloads the discharge pressure from the hydraulic pump. A first pump comprising a plurality of actuators connected in parallel driven by pressure oil and a comparator for comparing the hydraulic pressure of each actuator, and transmitting the discharge pressure of the hydraulic pump to the first pressure chamber of the main body. A hydraulic system characterized by having a pressure transmission line and a second pressure transmission line that converts electrical or pressure signals from the comparator into pressure and transmits the converted pressure to the second pressure chamber of the control board. Device.