JPS642802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a hydraulic pump of a hydraulic machine, such as a hydraulic excavator.

[Conventional technology]

FIG. 1 is a diagram showing an apparatus for implementing a conventional method for controlling a hydraulic pump of a hydraulic excavator. In the figure, 1 is a prime mover, 2 and 3 are variable displacement first and second hydraulic pumps driven by the prime mover 1 via a transmission 4, 5 is a swash plate of the hydraulic pump 2, and 6 is a swash plate of the swash plate 5. Regulators 7 to 9 for controlling the tilting angle are directional switching valves connected to the hydraulic pump 2, and each of the directional switching valves 7 to 9 is connected to an actuator (not shown). 10 to 12 are operating levers for operating the directional control valves 7 to 9;
13 to 15 are rods connecting the operating levers 10 to 12 and the directional control valves 7 to 9, 16 to 18 are cams attached to the rods 13 to 15, 19 is a fixed bracket, and 20 and 21 are rotatable to the fixed bracket 19. The movably attached link 22 is a roller rotatably attached to the links 20 and 21 at both ends, and 23 is a spring fixed to the link 20 at one end. Note that the hydraulic pump 3 also has the same configuration as the hydraulic pump 2.

In this control device, operation levers 10 to 1
When all rollers 2 are in the neutral state,
Since the links 20 and 21 are pressed against the recesses of the cams 16 to 18 by the spring 23,
At this time, the tilting angle of the swash plate 5 is minimized by the regulator 6, and the discharge amount of the hydraulic pump 2 is the minimum. In this state, for example, when the operating lever 12 is activated, the cam 18 moves, the roller 22 is pushed up by the cam 18, the links 20 and 21 rotate against the spring 23, and the links 20 and The rotation angle of the hydraulic pump 21 increases, and at this time, the tilt angle of the swash plate 5 is increased by the regulator 6, and the discharge amount of the hydraulic pump 2 becomes a value corresponding to the operation amount of the operation lever 12. That is, the discharge amount of the hydraulic pump 2 has a value corresponding to the maximum amount of operation of the operating levers 10 to 12, that is, the maximum amount of operation. In addition, hydraulic pump 2
When the discharge pressure of the hydraulic pump 2 increases to a predetermined value or more, the tilt angle of the swash plate 5 is decreased by the regulator 6 in accordance with the discharge pressure, so that the discharge amount of the hydraulic pump 2 is decreased in accordance with the discharge pressure.

That is, in the conventional hydraulic pump control method, the maximum discharge amount of the hydraulic pump 2 is controlled by controlling the operating lever 10.
-12, and when the discharge pressure of the hydraulic pump 2 exceeds a predetermined value, the discharge amount of the hydraulic pump 2 is decreased in accordance with the discharge pressure. Similar control is performed on the hydraulic pump 3 as well. In this way, if the maximum discharge amount of the hydraulic pumps 2 and 3 is set to a value corresponding to the maximum operation amount of the control lever, the discharge amount of the hydraulic pumps 2 and 3 will be the minimum when work is interrupted, and
Since the input to the hydraulic pumps 2 and 3, that is, the output of the prime mover 1, is minimized, fuel consumption can be saved. Furthermore, when the discharge pressure of the hydraulic pumps 2 and 3 exceeds a predetermined value, the discharge amount of the hydraulic pumps 2 and 3 is reduced according to the discharge pressure, so the input of the hydraulic pumps 2 and 3, that is, the output of the prime mover 1. Since the engine speed can be limited to a predetermined value or less, it is possible to prevent the engine 1 from stalling.

[Problem to be solved by the invention]

However, in such a hydraulic pump control method for a hydraulic machine, when the discharge pressure of the hydraulic pump 2 increases, for example, even if the sum of the inputs of the hydraulic pumps 2 and 3 does not exceed the output of the prime mover 1, the hydraulic pump 2
Since the discharge amount of the motor 1 decreases, the output of the prime mover 1 cannot be used effectively. In addition, hydraulic pump 2
actuator and hydraulic pump 3 connected to
When operating the actuator connected to the hydraulic pump 2 to control the bucket locus during ground leveling work, slope work, etc., if the load on the actuator connected to one of the hydraulic pumps, for example hydraulic pump 2, increases, the hydraulic The discharge pressure of the pump 2 increases, the discharge amount of the hydraulic pump 2 decreases, and the speed of the actuator connected to the hydraulic pump 2 is proportional to the discharge amount of the hydraulic pump 2. Since the speed of the actuator connected to the hydraulic pump 2 becomes smaller, unless the operation amount of the directional control valve is changed, the speed of the actuator connected to the hydraulic pump 2 and the speed of the actuator connected to the hydraulic pump 3 before the load on the actuator connected to the hydraulic pump 2 increases The ratio of the speed of the actuator connected to the hydraulic pump 2 is the ratio of the speed of the actuator connected to the hydraulic pump 2 to the speed of the actuator connected to the hydraulic pump 2 after the load on the actuator connected to the hydraulic pump 2 becomes large. Because of the difference, the trajectory of the bucket deviates from the trajectory intended by the driver. For example, if the speed of the actuator connected to hydraulic pump 2 is set to v ₁ and the speed of the actuator connected to hydraulic pump 3 is set to v ₂ in order to make the trajectory of the bucket a straight line, then the discharge of hydraulic pump 2 When the amount becomes 1/2, the speed of the actuator connected to hydraulic pump 2 becomes v ₁ /2, and the speed of the actuator connected to hydraulic pump 3 remains v ₂ . Since the ratio between the speed of the actuator connected to the hydraulic pump 3 and the speed of the actuator connected to the hydraulic pump 3 changes, the locus of the bucket deviates from a straight line. For this reason, in order for the trajectory of the bucket to match the trajectory intended by the driver, it is necessary to change the amount of operation of the directional control valve, making it difficult to control the trajectory of the bucket, and also to ensure the trajectory of the bucket. can't do it.

This invention was made to solve the above-mentioned problems, and is a hydraulic pump control for a hydraulic machine that can effectively utilize the output of a prime mover and easily and reliably control the trajectory of a working tool. The purpose is to provide a method.

[Means to solve the problem]

In order to achieve this object, in the present invention, a single prime mover drives variable displacement first and second hydraulic pumps, and each of the first and second hydraulic pumps is provided with a plurality of directional control valves. In the device for controlling the first and second hydraulic pumps of a hydraulic machine connected to an actuator via the device, the maximum operating amount of the operating lever for operating the directional switching valve connected to the first hydraulic pump, that is, A first maximum operation amount and a maximum operation amount of an operation lever for operating the directional control valve connected to the second hydraulic pump, that is, a second maximum operation amount are detected, and a throttle lever of the prime mover is detected. The rotation speed deviation between the output signal of the rotation speed detector and the output signal of the rotation speed detector is detected, and when the rotation speed deviation is small, the discharge amount signal is set to a predetermined maximum value and becomes smaller as the rotation speed deviation increases. and controlling the discharge amount of the first hydraulic pump with a first discharge amount control signal that is the product of the signal corresponding to the first maximum operation amount and the discharge amount signal, and The discharge amount of the second hydraulic pump is controlled by a second discharge amount control signal which is the product of a signal corresponding to the amount and the above-mentioned discharge amount signal.

In this hydraulic pump control method for a hydraulic machine, even if the discharge pressure of the first hydraulic pump or the discharge pressure of the second hydraulic pump increases, the sum of the inputs of the first and second hydraulic pumps is As long as it is smaller than the output, the rotation speed deviation does not increase much and the discharge amount signal does not become small, so the first and second discharge amount control signals do not become smaller, so the discharge amount of the first and second hydraulic pumps decreases. Moreover, when the sum of the inputs of the first and second hydraulic pumps exceeds the output of the prime mover, the rotation speed of the prime mover decreases, the rotation speed deviation increases, and the discharge amount signal becomes smaller. Since the first and second discharge amount control signals decrease at the same rate, the discharge amounts of the first and second hydraulic pumps decrease at the same rate.

[Embodiment] FIG. 2 is a diagram showing an apparatus for implementing the hydraulic pump control method for a hydraulic excavator according to the present invention, and FIG. 3 is a partially detailed view of the apparatus shown in FIG. 2.
In the figure, reference numeral 24 denotes a rotation angle detector for detecting the rotation angle of the links 20 and 21, and the cams 16 to 1
8. The links 20, 21, the rollers 22, the rotation angle detector 24, etc. constitute a device that detects the largest of the operating amounts of the operating levers 10 to 12, that is, the first maximum operating amount. 25 processes the output signal of the rotation angle detector 24 to obtain a first signal corresponding to the first maximum operation amount.
26 is a fuel injection pump of the prime mover 1; 27 is a throttle lever of the prime mover 1; 33 is a fuel injection pump body;
4 is a rack of the fuel injection pump main body 33; 35 is a spring that pulls the rack 34; 36 is an actuator that moves the rack 34 via a bell crank 37; 38 is a rack position detector; 28 is a fuel injection pump control device; 29 is an adder for the fuel injection pump control device 28; The difference, that is, the rotational speed deviation signal Δωe is determined.
30 is an adder of the fuel injection pump control device 28;
1 is an amplifier, 32 is a differential compensation circuit, the differential compensation circuit 32 differentiates the output signal of the rack position detector 38, and the adder 30 calculates the difference between the rotation speed deviation signal Δωe and the output signal of the differential compensation circuit 32. , amplifier 31
By amplifying the output signal of the adder 30 and controlling the actuator 36 with the output signal of the amplifier 31, the fuel injection amount of the fuel injection pump main body 33 is controlled, and the rotation speed of the prime mover 1 is controlled. Reference numeral 40 denotes a function generator, which inputs the rotational speed deviation signal Δωe, and when the rotational speed deviation signal Δωe is small, the maximum value is 1, and when the rotational speed deviation signal Δωe exceeds a predetermined value, the rotational speed is increased. A discharge amount signal K that becomes smaller as the deviation signal Δωe becomes larger is output. 41 obtains a first discharge amount control signal which is the product of the discharge amount signal K and the first maximum operation amount signal, and controls the regulator 6 with the first discharge amount control signal to control the discharge amount of the hydraulic pump 2. This is a multiplier to control.
Note that the hydraulic pump 3 also has the same configuration as the hydraulic pump 2.

FIG. 4 is a diagram showing another device for carrying out the hydraulic pump control method for a hydraulic excavator according to the present invention. In the figure, 42 to 44 refer to the operating lever 1.
Hydraulic pilot valves 42 to 44 are hydraulic pilot valves operated by directional control valves 7 to 12.
~9 pilot ports. 45
-49 are shuttle valves, and the shuttle valves 45-49 select the maximum output pressure from the hydraulic pilot valves 42-44. 50 is a pressure detector that detects the output pressure of the shuttle valve 49;
~49, the pressure detector 50 constitutes a device for detecting the first maximum operation amount. In addition, hydraulic pump 3
The configuration of the hydraulic pump 2 is also similar to that of the hydraulic pump 2.

That is, in the control method according to the present invention, the maximum operation amount of the operation lever of the directional control valve connected to the hydraulic pump 2, that is, the first maximum operation amount, and the directional control valve connected to the hydraulic pump 3 Detects the maximum operation amount of the operation lever of the motor 1, that is, the second maximum operation amount.
Detects the rotational speed deviation, and from the rotational speed deviation, calculates a discharge amount signal K which is 1 when the rotational speed deviation is small, and which decreases as the rotational speed deviation increases when the rotational speed deviation exceeds a predetermined value. , the discharge amount of the hydraulic pump 2 is controlled by the first discharge amount control signal which is the product of the discharge amount signal K and the first maximum operation amount signal corresponding to the first maximum operation amount, and the discharge amount signal K and The discharge amount of the hydraulic pump 3 is controlled by the second discharge amount control signal, which is the product of the second maximum operation amount signal and the second maximum operation amount signal.

In this way, when the load acting on the actuator is small and the discharge pressure of the hydraulic pumps 2 and 3 is low, the rotation speed of the prime mover 1 will be a value corresponding to the operation amount of the throttle lever 27, so that the rotation speed deviation is small, the discharge amount signal K is 1, and the discharge amount control signal has a value corresponding to the first and second maximum operation amount signals, so the discharge amount of the hydraulic pumps 2 and 3 is equal to the first and second maximum operation amount signals. The value corresponds to the maximum operation amount. Also,
For example, even if the load on the actuator connected to the hydraulic pump 2 increases and the discharge pressure of the hydraulic pump 2 increases, the discharge pressure of the hydraulic pump 3 is low, so the sum of the inputs of the hydraulic pumps 2 and 3 becomes the prime mover. 1, the rotation speed of the prime mover 1 does not decrease and the rotation speed deviation is small, so the discharge amount signal K is 1, and the first and second discharge amount control signals are Since the value corresponds to the maximum operation amount signal of No. 2, the discharge amount of the hydraulic pumps 2 and 3 becomes a value according to the first and second maximum operation amounts. Then, when the load acting on the actuator increases and the sum of the inputs of the hydraulic pumps 2 and 3 becomes greater than the output of the prime mover 1, the rotational speed of the prime mover 1 decreases without changing the amount of operation of the throttle lever 27. , the rotation speed deviation increases and the discharge amount signal K becomes smaller than 1, so the first and second discharge amount control signals become smaller than the first and second maximum operation amount signals, so the hydraulic pump 2 , 3 is smaller than the value corresponding to the first and second maximum operation amounts. In this case, since the discharge amounts of the hydraulic pumps 2 and 3 both decrease at the same rate according to the discharge amount signal K, the hydraulic pump 2 before the sum of the inputs of the hydraulic pumps 2 and 3 becomes larger than the output of the prime mover 1 The ratio of the speed of the connected actuator to the speed of the actuator connected to the hydraulic pump 3 and the actuator connected to the hydraulic pump 2 after the sum of the inputs of the hydraulic pumps 2 and 3 becomes larger than the output of the prime mover 1. Since the ratio of the speed of the bucket and the speed of the actuator connected to the hydraulic pump 3 is the same, the trajectory of the bucket will deviate from the trajectory intended by the driver even if the amount of operation of the directional control valve is not changed. Never. For example, when the speed of the actuator connected to hydraulic pump 2 is set to v ₁ and the speed of the actuator connected to hydraulic pump 3 is set to v ₂ in order to make the trajectory of the bucket a straight line, the discharge amount signal K is When it becomes 1/2, the discharge amount of hydraulic pumps 2 and 3 becomes 1/2, the speed of the actuator connected to hydraulic pump 2 becomes v ₁ /2, and the speed of the actuator connected to hydraulic pump 3 becomes v ₂ /2
Therefore, since the ratio between the speed of the actuator connected to hydraulic pump 2 and the speed of the actuator connected to hydraulic pump 3 does not change, the trajectory of the bucket can be changed from a straight line without changing the operating amount of the directional control valve. It won't fall off. For this reason,
The trajectory of the bucket can be controlled easily and reliably.

In the above-mentioned embodiment, a method for controlling a hydraulic pump of a hydraulic excavator has been described, but it goes without saying that the present invention can be applied to a method of controlling a hydraulic pump of other hydraulic machines. Further, in the above-described embodiment, the signals corresponding to the first and second maximum operation amounts are processed by the function generator 25, but the processing by the function generator 25 can also be omitted. Furthermore, in the above embodiment, the cams 16 to 18, the links 20, 2
1, the roller 22, the rotation angle detector 24, and the like constitute the device for detecting the first maximum operation amount, but the configuration of the device for detecting the first maximum operation amount is not limited to this.

〔Effect of the invention〕

As explained above, in the method for controlling a hydraulic pump for a hydraulic machine according to the present invention, even if either the discharge pressure of the first hydraulic pump or the discharge pressure of the second hydraulic pump becomes higher, the As long as the total input to the first and second hydraulic pumps is smaller than the output of the prime mover, the discharge amounts of the first and second hydraulic pumps are not reduced, so the output of the prime mover can be used effectively. Furthermore, when the total input of the first and second hydraulic pumps exceeds the output of the prime mover, the discharge amount of the first hydraulic pump and the discharge amount of the second hydraulic pump decrease at the same rate. 1
Since the speed of the actuator connected to the first hydraulic pump and the speed of the actuator connected to the second hydraulic pump decrease at the same rate, the trajectory of the work implement can be adjusted to the operator's direction without changing the amount of operation of the directional control valve. Since the tool will not deviate from its intended trajectory, the trajectory of the work tool can be controlled easily and reliably. As described above, the effects of this invention are remarkable.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a device for implementing a conventional method for controlling a hydraulic pump of a hydraulic excavator;
The figure shows a device for implementing the hydraulic pump control method for a hydraulic excavator according to the present invention, FIG. 3 is a partially detailed view of the device shown in FIG. 2, and FIG. 4 shows a hydraulic excavator according to the present invention. FIG. 3 is a diagram showing another device for implementing the hydraulic pump control method of FIG. 1... Prime mover, 2, 3... Hydraulic pump, 6...
Regulator, 7-9... Directional switching valve, 10-1
2... Operation lever, 13-15... Rod, 16
~18...Cam, 19...Fixed bracket, 2
0, 21... Link, 22... Laura, 23...
Spring, 24...Rotation angle detector, 26...Fuel injection pump, 27...Throttle lever, 2
9, 30... Adder, 38... Rack position detector, 39... Rotation speed detector, 40... Function generator, 41... Multiplier, 42-44... Hydraulic pilot valve, 45-49... ...Shuttle valve, 50...Pressure detector.

Claims (1)

[Claims] 1. The above-mentioned hydraulic machine, in which a single prime mover drives variable displacement first and second hydraulic pumps, and actuators are connected to the first and second hydraulic pumps through a plurality of directional control valves, respectively. 1. In a device for controlling a second hydraulic pump, a maximum operation amount of an operating lever for operating the directional control valve connected to the first hydraulic pump, that is, a first maximum operation amount and the second maximum operation amount. Detects the maximum operation amount, that is, the second maximum operation amount, of the control lever for operating the directional switching valve connected to the hydraulic pump, and also detects the output signal of the throttle lever of the prime mover and the output signal of the rotation speed detector. Detect the rotational speed deviation from the rotational speed deviation, and when the rotational speed deviation is small, a predetermined value of the maximum value is obtained, and a discharge amount signal that decreases as the rotational speed deviation increases is determined, and the discharge amount signal is set to the first maximum operation amount. The discharge amount of the first hydraulic pump is controlled by a first discharge amount control signal which is the product of a signal corresponding to the second maximum operation amount and the discharge amount signal, and a signal corresponding to the second maximum operation amount and the discharge amount signal are controlled. A method for controlling a hydraulic pump for a hydraulic machine, characterized in that the discharge amount of the second hydraulic pump is controlled by a second discharge amount control signal that is the product of .