JPH087165Y2 - Swash plate controller for variable displacement hydraulic pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a swash plate control device for a variable displacement hydraulic pump.

(Prior Art) A conventional hydrostatic drive system will be described with reference to FIG.
(1) is a prime mover, (2) is a variable displacement hydraulic pump driven by the prime mover (1), (3) is a hydraulic actuator such as a hydraulic motor, and (4) is a hydraulic actuator (3). Load, (5) is the operating lever,
(6) is a swash plate control device, (7) is the same swash plate control device (6)
The swash plate drive device (8) for changing the discharge capacity of the hydraulic pump (3) by the output of is a crossover relief valve, and the hydraulic pump (2) and the hydraulic actuator (3) are connected by a closed circuit. Further, in FIG. 5 showing the details of the swash plate control device (6), (9) to (14) are respective devices of the swash plate control device (6), and (15) is a hydraulic pump (2) and a hydraulic actuator. (3) is a hydrostatic drive system. Also, among the devices of the swash plate control device (6), (9)
Is a comparison point for comparing the hydraulic actuator speed command signal ω _s from the operating lever (5) and the actual actuator speed detection signal ω _a of the hydraulic actuator (3), (10) is a function generator, and (16) is horsepower. Setting differential pressure signal P _s from the setting device, (17) is the minimum value selector, and (11) is the minimum value selector (17)
A hydraulic actuator (3) compare points for comparing the operating pressure detection signal P _a of, (12) the control calculator (14) is off Eid-back gain, (13) the speed detection signal of the hydraulic actuator (3) Is added with the signal e _a obtained by multiplying the feedback back gain (14) by the pressure control signal e _p of the control calculator (12), and (7) is the swash plate drive device and the operating lever ( When 5) is operated, the hydraulic actuator speed command signal ω _s from the operating lever (5) and the actuator speed detection signal ω _a from the hydraulic actuator (3) enter the comparison point (9), and are compared here. the resulting deviation signal Δω enters function generator (10), wherein the hydraulic set differential pressure P _l of actuator (3) are determined, determined by the set differential pressure P _l and horsepower setter (16) Set differential pressure Pω
And are entered in the minimum value selector (17), where the set differential pressures P _l , Pω
The smaller one is selected. Further, the set differential pressure signal P _{s of} the minimum value selector (17) and the operating pressure detection signal P _a of the hydraulic actuator (3) enter the comparison point (11), where they are compared and the pressure obtained as a result is compared. The deviation signal ΔP enters the control calculator (12), where the pressure control signal e _p is calculated. The pressure control signal e _p and the speed detection signal ω _a from the hydraulic actuator (3) are fed to the feedback control gain ( The signal e _a obtained by multiplying by 14) enters the addition point (13) and is added here, and the resulting signal e enters the swash plate drive device (7), and the swash plate drive device ( 7) activated, hydraulic pump (2)
Of the hydraulic actuator (3) is controlled to control the operating pressure and speed of the hydraulic actuator (3).

The characteristics of the function generator (10) and the minimum selector (17) are shown in FIG. The input to the same function generator (10) is the speed deviation signal Δω between the actuator speed command signal ω _s from the operating lever (5) and the speed detection signal ω _a from the hydraulic actuator (3), and the minimum value selection The output from the device (17) is the set differential pressure signal P _s . The set differential pressure signal P _s is proportional to the speed deviation signal Δω when the speed deviation signal Δω is between −ω _c and ω _c , and has the maximum negative difference when the speed deviation signal Δω is −ω _c or less. The pressure becomes −P _max , and when the speed deviation signal Δω is ω _c or more, the maximum positive differential pressure P _max is obtained. The operation of the control calculator (12) is shown in FIG. The control computing unit (12) is PI control, and the pressure deviation signal ΔP is added to a value obtained by multiplying the pressure deviation signal ΔP by a time constant (12a) and then integrating by the integrator (12b). (12
It is input to c), added, and then multiplied by the proportional gain (12d) to output the pressure control signal e _p obtained. The control calculator controls the pressure deviation ΔP to zero.

(Problems to be Solved by the Invention) In the swash plate control device for the variable displacement hydraulic pump shown in FIGS. 4 to 7, the hydraulic actuator (3) and the load (inertial body) (4) are driven by a speed reducer. Although connected, the gear of the reduction gear has a backlash, and when the hydraulic actuator (3) stops, the gear is moved from the inertial body side in the direction to eliminate the backlash, and until the backlash disappears, the hydraulic actuator (3) moves. The circuit pressure between the hydraulic pump (2) and the hydraulic actuator (3) is low because the load is not applied to 3), but when the backlash disappears, the hydraulic actuator (3) is suddenly loaded with the circuit pressure. Suddenly rises, the pressure control system works to decrease the circuit pressure, the hydraulic actuator (3) operates in the opposite direction, and there is no backlash in the opposite direction. As a result, the circuit pressure rises sharply in the opposite direction. Since the above operation is repeated, there has been a problem that severe hunting occurs after the hydraulic actuator (3) is stopped.

The present invention is proposed in view of the above problems, and an object of the present invention is to provide a hydraulic actuator for a load drive even if there is a backlash in a gear of a reduction gear interposed between the hydraulic actuator for load drive and the load. Another object of the present invention is to provide a swash plate control device for a variable displacement hydraulic pump capable of preventing the hunting phenomenon due to backlash in the stop range and the steady speed range.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention relates to a variable displacement hydraulic pump (2) and a hydraulic pump (2) directly connected via a closed circuit and via a speed reducer. In the control device for the hydrostatic drive (15) consisting of the hydraulic actuator (3) connected to the load (4), the actuator speed command signal ω _s and the speed detection provided on the shaft connected to the load (4). The swash plate angle that decreases the swash plate angle when the speed deviation signal Δω from the actuator speed detection signal ω _a obtained from the device is less than a predetermined value and the actuator speed detection signal ω _a is larger than the actuator speed command signal ω _s is negative. Outputs the command signal and outputs the speed deviation signal Δ
Speed with a function generator (18) that outputs a swash plate angle command signal that increases the swash plate angle when ω is less than a predetermined value and the actuator speed command signal ω _s is larger than the actuator speed detection signal ω _a A control circuit (A), a pressure setter (19) for setting a positive maximum pressure when the speed deviation signal Δω is positive, and a negative maximum pressure when the speed deviation signal Δω is negative, A minimum value selector (17) that selects the minimum value of the maximum set pressure signal P _m from the pressure setter (19) and the set pressure signal P _w from the horsepower setter (16), and the same minimum value selector A pressure control circuit comprising a control calculator (12) for calculating a pressure control signal based on a pressure deviation signal Δp obtained by comparing the set differential pressure signal from (17) with the actuator operating pressure detection signal P _a ( and B), the actuator operating pressure of the circuit pressure output signal P _a is low pressure control circuit ( ) Output is greater than the output of the speed control circuit (A). Select the output of the speed control circuit (A) for the stop area and steady speed area of the hydraulic actuator (3), and select the pressure for the acceleration area and deceleration area. A minimum value selector (20) for selecting the output of the control circuit (B), and an output signal e _p from the minimum value selector (20) and an actuator speed detection signal ω _a from the hydraulic actuator (3).
Is added to the signal e _a obtained by multiplying the gain to obtain a swash plate control signal e, which is output to the swash plate drive device (7) of the variable displacement hydraulic pump (2) to output the hydraulic pump (2). The swash plate angle is controlled to prevent the hunting phenomenon due to the backlash of the gears of the speed reducer in the stop range and the steady speed range of the hydraulic actuator (3).

(Operation) The swash plate control device of the variable displacement hydraulic pump of the present invention is configured as described above, and in the stop region and the steady deceleration region of the load driving hydraulic actuator (3), the actuator operating pressure detection signal (circuit Since the pressure P _a is low, the output of the pressure control circuit (B) becomes larger than the output of the speed control circuit (A), and the minimum value selector (20) causes the speed control circuit (A) (function generator (18 ), And the signal e _a obtained by multiplying the output signal e _p from the minimum value selector (20) and the actuator speed detection signal ω _a from the hydrostatic drive (15) by _a gain. To output a swash plate control signal e to the swash plate drive device (7) of the variable displacement hydraulic pump (2) to control the swash plate angle of the hydraulic pump (2), The stop area, acceleration area, deceleration area of the hydraulic actuator (3),
And reducer in steady speed range (hydraulic actuator (3)
The hunting phenomenon due to the backlash of the gears of the speed reducer interposed between the load and the load (4) is prevented.

(Embodiment) Next, a swash plate control device for a variable displacement hydraulic pump according to the present invention will be described with reference to an embodiment shown in FIGS. 1, 2, and 3. FIG. 1A shows a speed control circuit, and FIG. ) Is a pressure control circuit, (5)
Is an operating lever, and (18) is a function generator of the speed control circuit (A). The function generator (18) is obtained by comparing the actuator speed command signal ω _s and the actuator speed detection signal ω _a . When the speed deviation value Δω is less than a predetermined value and the actuator speed detection signal ω _a is larger than the actuator speed command signal ω _s, a swash plate command signal that decreases the swash plate angle is output, and the speed deviation value Δω is the predetermined value. Below the value, the actuator speed command signal ω _s becomes the actuator speed detection signal ω _a
When the positive value is larger than the above, a swash plate command signal for increasing the swash plate angle is output. Also (11) (12) (1
6) (17) (19) is each device of the pressure control circuit (B), of which (19) sets the maximum positive pressure when the speed deviation value Δω is positive, and the speed deviation value Δω is When the pressure is negative, a pressure setter that sets a negative maximum pressure, (16) a horsepower setter that sets a differential pressure, and (17) a maximum set pressure signal P _m from the pressure setter (19) and the horsepower. Comparative minimum value selector for selecting the minimum value between the set pressure signal P _w from setter, and an actuating pressure detection signal P _a set pressure signal and a hydraulic actuator (11) is the minimum value selector (17) comparison points, (12) on the pressure deviation signal Δp obtained by comparing the actuator operating pressure detection signal P _a from the minimum value selector (17) setting the difference from pressure signal and a hydraulic drive system (15) A control calculator (20) for calculating a pressure control signal based on the swash plate command signal from the function generator (18) and the control calculator (12) The minimum value selector for selecting the minimum value of the pressure control signal al, (13) the signal e obtained by multiplying the full Eid-back gain in speed detection signal omega _a of the hydraulic drive system (15) (14) output signal e _p and summing point for adding from _a and the minimum value selector (20), the hydraulic drive system receives a signal e from (7) is the summing point (13) (15)
Is a swash plate drive device for driving the swash plate of the variable displacement hydraulic pump of FIG. The function of the function generator (18) is shown in FIG. When the velocity deviation signal Δω from the comparison point (9) is positive and larger than Δω _v , the swash plate command signal Δφ _v having a constant value
Is output and when 0 <Δω <Δω _v , a swash plate command signal proportional to the speed deviation signal Δω is output. The operation of the pressure setting device (19) is shown in FIG. When the speed deviation signal Δω is positive, the positive maximum set pressure signal P _max is output, and when the speed deviation signal Δω is negative, the negative maximum set pressure signal −P _max is output.

Next, the operation of the swash plate control device for the variable displacement hydraulic pump shown in FIGS. 1, 2, and 3 will be specifically described.

First, the acceleration range will be explained. By operating the operating lever (5), the speed command signal ω of the hydraulic actuator (3) is
Set _s . Since the speed detection signal ω _a of the hydraulic actuator (3) in the acceleration region is smaller than ω _s , the speed deviation signal Δω becomes positive. Therefore, the pressure setter (19) outputs a positive maximum set pressure signal P _max . In addition, the set pressure signal P _w from the horsepower setting device (16) and the maximum setting pressure signal P _m (= P _max ) from the pressure setting device (19) are the minimum value selector (17).
The minimum value is selected here, and the minimum value selector (1
The output signal from 7) and the operating pressure detection signal P _a from the hydraulic actuator (3) enter the comparison point (11), are compared here, and the resulting pressure deviation signal ΔP is the control calculator (12). )to go into. In the control calculator (12), the comparison point (11)
The calculation is performed so as to make the differential pressure ΔP at 0 to 0, and the signal obtained as a result is output. On the other hand, the function generator (18) outputs a swash plate command signal Δφ _s when the speed deviation signal Δω from the comparison point (9) is Δω _v or more, and when Δv _v or less, the swash plate proportional to Δω Output a command signal. The output signal of the same function generator (18) and the output signal of the control arithmetic unit (12) enter the minimum value selector (20), where the minimum value is selected and the minimum value selector (20) The output signal e _p and the signal e _a obtained by multiplying the hydraulic actuator speed detection signal ω _a by the gain (14) enter the addition point (13) where they are added and the swash plate command obtained as a result The signal e enters the swash plate drive (7). In the acceleration region, due to the relatively high actuator operating pressure detection signal (circuit pressure) P _a, the control calculator (1
The output signal of 2) becomes lower than the output signal of the function generator (18), and the pressure is controlled only by the pressure control circuit (B) to smoothly accelerate.

Next, the steady region will be described. In the steady state region, the actuator operating pressure detection signal (circuit pressure) P _a becomes low and the differential pressure ΔP at the comparison point (11) becomes large.
The output of 2) also becomes large. On the other hand, the speed detection signal ω _a of the hydraulic actuator approaches the set value ω _s , the speed deviation signal Δω becomes smaller and becomes Δω _v or less, so the output of the function generator (18) decreases in proportion to Δω. To do. That is, in the steady state, the output of the function generator (18) is the minimum value selector (20).
And is kept at a steady rotation.

Next, the deceleration area will be described. When the operating lever (5) is moved to the neutral position, the actuator speed command signal ω _s
Becomes zero, the speed deviation value Δω becomes a negative value, and the output P _{m of} the pressure setter (19) becomes the maximum negative value -P _max . At this time, the set differential pressure signal P _w from the horsepower setter (16) also has a negative value, and the smaller absolute value of P _m and P _w is the minimum value selector (1
The set pressure signal selected by 7) and the negative actuator working pressure detection signal (circuit pressure) P _a enter the comparison point (11) and are compared here, and the resulting pressure deviation signal is obtained. ΔP enters the control calculator (12), where the calculation for making ΔP zero is performed and the calculation result is output.
On the other hand, the function generator (18) also outputs -Δφ _v when the speed deviation Δω is −ω _s or less. In the same deceleration range, the pressure deviation signal ΔP is small and the output signal from the control calculator (12) is smaller than the output signal from the function generator (18). Therefore, the output signal from the control calculator (12) is small. Is selected by the minimum value selector (20), and the hydraulic actuator is smoothly decelerated.

Next, the stop area will be described. The stop range, actuator hydraulic pressure detection signal (circuit pressure) P _a is lowered, the absolute value of the pressure difference signal ΔP at the comparison point (11) increases, also increases the output from the control calculator (12) . on the other hand,
The speed detection signal ω _a of the hydraulic actuator is the set value ω
_Since it approaches _s (= 0), the speed deviation signal Δω becomes smaller, and the minimum value selector (20) selects the output of the function generator (18). When the speed deviation signal Δω is negative (actuator speed detection signal ω _a > 0), the function generator (18) outputs a negative value proportional to Δω, reduces the swash plate angle, and increases the positive (actuator speed When the detection signal ω _a <0, the function generator (18) outputs a positive value proportional to Δω to increase the swash plate angle, and the hydraulic actuator speed gradually decreases to zero. In the stop region, since the signal of the pressure control circuit (B) is not used as described above, it is not adversely affected by the pressure, and therefore hunting does not occur even if the gear of the reduction gear has a backlash.

(Effect of the Invention) As described above, the swash plate control device for the variable displacement hydraulic pump of the present invention has the actuator operating pressure detection signal (circuit pressure) P in the stop range and the steady speed range of the load drive hydraulic actuator (3). _{Since a} is low, the output of the pressure control circuit (B) becomes larger than the output of the speed control circuit (A), and the minimum value selector (20) causes the speed control circuit (A) (output of the function generator (18) to Then, add the output signal e _p from the same minimum value selector (20) and the signal e _a obtained by multiplying the actuator speed detection signal ω _a from the hydrostatic drive (15) by the gain. To output the swash plate control signal e to the swash plate drive device (7) of the variable displacement hydraulic pump (2) to control the swash plate angle of the hydraulic pump (2), and thus to drive the load. Teeth of the reduction gear interposed between the hydraulic actuator (3) and the load (4) Even if the vehicle has backlash, there is an effect that the hunting phenomenon due to the backlash in the stop range and the steady speed range of the hydraulic actuator can be prevented.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a swash plate control device for a variable displacement hydraulic pump according to the present invention, FIG. 2 is an operation explanatory diagram of a function generator, and FIG. 3 is an operation explanatory diagram of a pressure setting device. , FIG. 4 is a system diagram showing a hydrostatic drive device, FIG. 5 is a system diagram showing a conventional swash plate control device for a variable displacement hydraulic pump, and FIG. 6 is an explanatory view of the function generator function, FIG. [Fig. 4] is an operation explanatory view of a control calculator. (A) ... speed control circuit, (B) ... pressure control circuit,
(2) ... Variable displacement hydraulic pump, (3) ... Actuator, (5) ... Operating lever, (6) ... Swash plate control device, (7) ... Swash plate drive device, (9) ( 11) …… Comparison point, (12) …… Control calculator, (13) …… Addition point, (16)
...... Horse power setting device, (17) …… Minimum value selector, (18) ……
Function generator, (19) …… Pressure setter, (20) …… Minimum value selector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masatoshi Miki Creator Masatoshi Miki 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. (56) References JP-A-62-31766 (JP, A) JP-A-SHO 60-263770 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A static displacement actuator comprising a variable displacement hydraulic pump (2) and a hydraulic actuator (3) directly connected to the hydraulic pump (2) via a closed circuit and connected to a load (4) via a speed reducer. In the control device for the hydraulic drive (15), the speed deviation signal Δω between the actuator speed command signal ω _s and the actuator speed detection signal ω _a obtained from the speed detector provided on the shaft connected to the load (4) When the actuator speed detection signal ω _a is larger than the actuator speed command signal ω _{s at a} predetermined value or less, a swash plate angle command signal for decreasing the swash plate angle is output, and the speed deviation signal Δω is output.
Is a predetermined value or less and the actuator speed command signal ω _s is larger than the actuator speed detection signal ω _a and is positive, the speed control is equipped with a function generator (18) that outputs a swash plate angle command signal to increase the swash plate angle. A circuit (A) and a pressure setter (19) for setting a maximum positive pressure when the speed deviation signal Δω is positive and for setting a maximum negative pressure when the speed deviation signal Δω is negative. The minimum value selector (17) that selects the minimum value of the maximum set pressure signal P _m from the pressure setter (19) and the set pressure signal P _w from the horsepower setter (16), and the same minimum value selector ( The pressure deviation signal Δ obtained by comparing the set differential pressure signal from 17) with the actuator operating pressure detection signal P _a
The pressure control circuit (B) including a control calculator (12) for calculating the pressure control signal by p, and the output of the pressure control circuit (B) are speed control because the actuator pressure detection signal P _a of the circuit pressure is low. The output of the speed control circuit (A) is selected for the stop range and the steady speed range of the hydraulic actuator (3) which becomes larger than the output of the circuit (A), and the output of the pressure control circuit (B) is selected for the acceleration range and the deceleration range. It has a minimum value selector (20) for selecting an output, and is obtained by multiplying the output signal e _p from the minimum value selector (20) and the actuator speed detection signal ω _a from the hydraulic actuator (3) by a gain. a swash plate control signal e added was the signal e _a, which is outputted to the swash plate drive device for a variable-displacement hydraulic pump (2) (7), and controls the swash plate angle of the hydraulic pump (2) And the speed reducer in the stop range and steady speed range of the hydraulic actuator (3) Swash plate control device for a variable displacement type hydraulic pump is characterized in that to prevent the hunting phenomenon due Batsukuratsushiyu gears.