WO2001075309A1

WO2001075309A1 - Pump control method and pump control device

Info

Publication number: WO2001075309A1
Application number: PCT/JP2000/007152
Authority: WO
Inventors: Hideo Konishi; Kenji Arai; Seiichi Akiyama
Original assignee: Shin Caterpillar Mitsubishi Ltd.
Priority date: 2000-03-31
Filing date: 2000-10-16
Publication date: 2001-10-11
Also published as: JP2001280256A; JP3697136B2; CN1178003C; EP1207304A4; EP1207304A1; CN1353794A

Abstract

A variable displacement main pump (11) driven by an engine (13) is provided with a capacity control means (35) for variably controlling a discharge flow rate. According to an engine revolution speed detected by an engine revolution speed detector (44) and a pump discharge pressure from the main pump (11) detected by a pump discharge pressure detector (42), a power shift pressure output from a solenoid proportional reducing valve (46) is controlled by a signal output from a controller (45). The power shift pressure is led to a regulator control valve (39) of the capacity control means (35), and a tilt angle of the swash plate (36) of the main pump (11) is controlled by a regulator (37) to thereby shift-control pump discharge pressure - discharge flow rate characteristics to optimal levels. Whereby, a pump control device is provided that can reduce changes in engine revolution speed when a load pressure is rapidly changed.

Description

Light

Pump control method and pump control device

TECHNICAL FIELD The present invention relates to a pump control method and a pump device for controlling a variable displacement pump. Itoda

Background skill%

As shown in the official gazette of Japanese Utility Model Laid-open Publication No. 10-2202359, the control system of the variable displacement type pump for construction machinery such as hydraulic presses Then, receiving the signal from the engine speed detector for detecting the engine speed, a step-by-step process is performed on the engine speed in advance. The pump absorption torque that is continuous at the engine rated point and intersects at the engine rated point is set, and the pump absorption torque corresponding to the increase or decrease of the engine rotation speed is set. And adjusts the regulation of the variable-capacity pump based on the result of the operation, using the pump absorption torque as a predetermined value. As in the case of the one that outputs a command to the control valve, the conventional method detects the engine rotation speed and detects the pump absorption. The pump is operated to adjust the regulation of the variable-capacity pump, so that the engine can respond to sudden changes in negative pressure. There is a problem that the change in the number of rotations becomes large The present invention has been made in view of such a point, and a pump control method for reducing a change in the engine rotation speed in response to a sudden change in the load pressure. It is intended to provide a pump control device. Disclosure of the invention

The pump control method of the present invention has a capacity control means for detecting an engine rotation speed and being driven by the engine to variably control a pump discharge flow rate. The pump discharge pressure from the variable displacement pump is detected, and the engine shift speed and the pump shift pressure corresponding to the pump discharge pressure are detected. This is a method of controlling the pump discharge pressure-discharge flow characteristics of the variable displacement type positive pump by optimally guiding the force to the capacity control means. Then, the control signal for controlling the capacity control means by detecting the pump discharge pressure from the variable capacity pump is used, so that the load pressure can be changed suddenly. The change in the engine rotation speed can be reduced, and stable pump control can be realized.

Further, the pump control method of the present invention detects the engine rotation speed, and variably controls the pump discharge flow rate driven by the engine. Detects the pump discharge pressure from the variable displacement pump provided with a means, and controls the working fluid supplied to the load from the variable displacement pump. Negative control pressure generated by the neutral and fine operation of the control valve is controlled by displacement. The pump discharge flow is controlled to a minimum by guiding the pump discharge pressure to the displacement control means, and the pump is supplied from the engine to the variable displacement pump. The pump horsepower is controlled to a constant value, and the power shift pressure corresponding to the engine rotation speed and the pump discharge pressure is led to the capacity control means, and the pump of the variable displacement pump is controlled. This is a method of shifting the discharge pressure-discharge flow characteristics to the optimum one. Then, the negative control pressure generated due to the neutral state and fine operation state of the control valve is guided to the capacity control means, and the pump discharge is performed. The output flow can be controlled to a minimum, and when the negative control pressure drops, the pump discharge pressure is transferred to the capacity control means and the engine is controlled. The pump horsepower supplied to the variable displacement pump from the pump can be controlled at a constant level. The pump speed can be controlled according to the engine rotation speed and the pump discharge pressure. The shift pressure is guided to the capacity control means, and the pump discharge pressure-The discharge flow rate is controlled optimally by shift control, so that the engine responds to sudden changes in load pressure. The change in rotation speed can be reduced, and the capacity of the variable displacement pump can be controlled according to various situations. The ∎ it can control the optimum state.

Further, the pump control device of the present invention includes a displacement control means for variably controlling the discharge flow rate of a variable displacement pump driven by the engine; Engine rotation speed detection means for detecting the rotation speed, and pump discharge pressure detection for detecting the pump discharge pressure from the variable displacement pump The pumping means of the variable displacement pump which guides the power shift pressure corresponding to the discharge means and the engine rotation speed and the pump discharge pressure to the capacity control means. This device is provided with power shift control means for performing shift control on the output pressure-discharge flow characteristics optimally. Then, the pump discharge pressure detection means detects the pump discharge pressure from the variable displacement pump, and generates a control signal for controlling the capacity control means. Since the S-Shift control means is adopted, the change in the engine rotation speed in response to a sudden change in the load pressure can be reduced, and stable pump control can be realized. In addition, only the change to take in the pump discharge pressure as a control signal does not significantly change the current hardware. That is, it is possible to realize a good pump control device without drastic change of the system.

Further, a pump control device of the present invention includes a capacity control means for variably controlling the discharge flow rate of a variable displacement pump driven by an engine; Engine rotation speed detection means for detecting the rotation speed of the pump, pump discharge pressure detection means for detecting the pump discharge pressure from the variable displacement pump, and The pump discharge pressure of the variable displacement pump is obtained by introducing a know shift pressure corresponding to the engine rotation speed and the pump discharge pressure to the capacity control means. Novel shift control means for shifting and controlling the discharge flow characteristics optimally, and the pump discharge pressure to the capacity control means and the variable displacement type pump from the engine. Reduce the pump horsepower supplied to the pump The constant horsepower control means for constant control and the neutral and fine operation of the control valve for controlling the working fluid supplied to the load from the variable displacement pump. A negative control means for guiding the negative control pressure generated to the pump to the capacity control means so as to minimize the pump discharge flow rate. is there . Then, the negative control means can control the negative control pressure generated by the neutral state and fine operation state of the control valve. The pump discharge flow rate can be controlled to a minimum by leading to the capacity control means, and when the negative control pressure decreases, the constant horsepower control means allows the pump control flow rate to decrease. The pump discharge pressure is guided to the capacity control means to control the pump horsepower supplied to the engine or the variable capacity pump to a constant value, and the noise shift can be controlled. The power control pressure corresponding to the engine rotation speed and the pump discharge pressure is guided to the capacity control means by the pump control means, so that the pump discharge pressure is controlled. By controlling the discharge flow characteristic to the optimum one, it is possible to prevent sudden changes in the load pressure. That e emissions di emissions can a change in the rotational speed reduction, ∎ it can by volume system control control means an optimum state of the variable displacement Po down flop depending on the species' s situation.

In addition, the capacity control means includes a swash plate for variably adjusting the pump discharge flow rate, and a hydraulic mechanical actuator for controlling the tilt angle of the swash plate. The mechanical-regulator is equipped with a piston that operates in response to a Baneka in the direction to increase the tilt angle of the swash plate, and a piston that Ton Control in a direction that reduces the tilt angle of the swash plate by the fluid pressure that resists the force. It is equipped with a pilot-operated regulator control valve. Then, the signal pressure from the negative control means, the constant horsepower control means, and the nose shift control means is led to the pilot control type regulator control valve. In this way, the mechanical control valve can be used to control the piston of the mechanical control system with high accuracy by using the regulator control valve. By using the expression regulator as it is, it is possible to realize a good pump control device without changing the current hardware.

In addition, the noise shift control means includes a controller for calculating a noise shift pressure corresponding to the engine rotation speed and the pump discharge pressure. Controller and the regulator of the capacity control means in response to the electric signal output from the controller.-Controls the pilot pressure input to the evening control valve. An electromagnetic proportional operation valve is provided. An electromagnetic proportional operation valve that operates in response to an electric signal from the controller controls the control valve as desired, and the existing mechanical valve is controlled. Even during a regular evening, it is possible to control the pump discharge pressure-discharge flow characteristic to an ideal value. BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows one embodiment of the pump control device according to the present invention. FIG. 2 is a block diagram showing the function of the controller in the pump control device, and FIG. 3 is a block diagram showing the function of the controller in the pump control device. FIG. 5 is a characteristic diagram showing the engine speed versus output horsepower characteristic of the underspeed control torque calculation unit in the controller according to the first embodiment. Fig. 4 is a block diagram showing the function of the main pump allowable torque calculation unit in the controller, and Fig. 5 is a block diagram of the controller. FIG. 6 is a block diagram showing the function of the main pump control unit in the controller, and FIG. 6 is a block diagram showing the function of the main pump control unit in the same embodiment. Luk—Pump discharge pressure-flow characteristic diagram for explaining the first breakpoint pressure conversion, and FIG. 7 shows the pump discharge pressure FIG. 4 is a characteristic diagram showing characteristics of the discharge flow rate of a pump. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 shows the hydraulic circuit of the hydraulic shovel. Hydraulic shovels (not shown) are attached to the upper rotating body on the lower traveling body, the left and right traveling hydraulic motors, the turning hydraulic motors and the front working machine. Supply the main pump 11 as a pair of variable displacement pumps for supplying hydraulic oil to the hydraulic cylinder, and the nozzle pressure for control The "North" pumps 12 and the engines 13 which drive these main pumps 11 and the pilot pumps 12; hydraulic Each of the evening tanks 14 and 14 for storing the hydraulic oil of the circuit is mounted.

In addition, the hydraulic pressure level of the hydraulic hydraulic motors for left and right, hydraulic hydraulic motors for turning, and hydraulic hydraulic cylinders for the front working machine It has a hydraulic circuit that controls the operation of the damper.

This hydraulic circuit is composed of a pair of main pumps 11 to the left and right hydraulic motors for traveling, hydraulic motors for swiveling, and front operation. Control valve 15 for directional control and flow control of the hydraulic oil supplied to each hydraulic cylinder of the industrial machine, and the control valve Turn valve 15 off. The remote control is performed by the hydraulic pressure supplied from the outlet pump 12, and the pilot valve (hereafter, this pilot valve) Are referred to as “remote control valves 16”) and hydraulic passages for connecting these to the pipes.

The control valve 15 has various stems (spools) for directional control and flow rate control of the hydraulic oil, and the traveling hydraulic pressure motor on the left side. The left traveling control stem 21 for controlling the motor, the right traveling control stem 22 for controlling the right traveling hydraulic motor, and the turning Rotation control system 23 for controlling hydraulic pressure and hydraulic control, and first boom control system 24 for controlling boom hydraulic cylinder And the second stage 25 and the first stage 26 and the second stage for the stage control for controlling the hydraulic cylinder for the stage. Stem 27 and hydraulic cylinder for rocket A socket control system 28 for controlling the head, and a head control attached to the tip of the stick instead of the socket Attachment control stage 29 for simplification is connected to two groups corresponding to the two main pumps 11 in a non-linear manner. It is well located. Supply hydraulic oil only from the main pump 11 to the left drive control stem 21 and right drive control stem 22 only. A straight-moving control stage 30 is also provided to drive straight ahead by driving the right-hand hydraulic pressure motor at a constant speed.

Although only a part of the remote control valve 16 is shown in the drawing, the remote control valve 16 is manually operated by an operating lever in an operating chamber of a hydraulic pressure cab. The depressurization control of the pipe outlet pressure oil supplied from the nozzle outlet pump 12 via the nozzle outlet pressure communication line 31 reduces the pressure by controlling the pressure. It has a pressure reducing valve 32 that supplies the pressure chamber at the end of each stem of the cooling valve 15. In addition, a relief valve for maintaining the nozzle pressure at the set pressure together with the filter unit 33 in the neurot pressure passage 31. 34 are set up.

The pair of main pumps 11 are provided with capacity control means 35 for variably controlling the pump discharge flow rate, and the capacity control means 35 is provided with an inclination. Pump displacement is controlled in accordance with the turning angle.Swash plate 36 and swash plate 36 that control the displacement angle by controlling the volume and controlling the tilt angle of the swash plate 36 It is equipped with a mechanical regulator and a 37-inch mechanical regulator. These mechanical leg spacers 37 are provided with a piston 38 which operates in response to non-directions for increasing the tilting angle of the swash plate 36, and a piston 38 which operates. The piston 38 of this type is controlled in a direction in which the tilt angle of the swash plate 36 is reduced by a fluid pressure (hydraulic pressure) that resists the force of noise. A gear control valve 39 is provided. These regulation overnight control valves 39 are integrally incorporated in a regulation main body in which the piston 38 is built-in.

The pump discharge pressure of each main pump 11 is applied to one end of each piston 38, and the other end of each piston 38 is connected to the other end. Along with the lever, a control pressure in which the pump discharge pressure is controlled by each of the regulator control valves 39 is used. Each swash plate 36 is provided with a swash plate position detector (not shown) for detecting a tilt angle (swash plate position).

The discharge passages from the two main pumps 11 are connected to the pump passages via a shut-off valve 41 for extracting the high-pressure side pump discharge pressure. A pump discharge pressure detector 42 for detecting the pump discharge pressure is connected as a means for detecting the pump discharge pressure.

The engine 13 has an engine speed (hereinafter referred to as “engine speed” or “engine speed”). ) And the engine rotation speed detection means as the engine rotation speed detection means for detecting the engine rotation speed. It is equipped with a vessel 44. The target number of revolutions of the engine 13 is an accelerator dial as a means for setting the number of revolutions, or an underspeed for setting the underspeed with respect to the rated speed. Set by under speed setting means.

The engine rotation speed and the pump discharge pressure detected by the engine rotation speed detector 44 and the pump discharge pressure detector 42 described above. The node shift pressure P s corresponding to the pressure is supplied to the capacity control means 35 of the main pump 11 and the pump discharge pressure of the main pump 11 — As a power shift control means that shifts the discharge flow characteristics to the optimum value, it responds to the engine rotation speed and the pump discharge pressure. A controller 45 'for calculating the noise shift pressure Ps, and a regulator in response to an electric signal output from the controller 45. — Nozzle pressure input to evening control valve 39, ie, electromagnetic proportional pressure reducing valve as an electromagnetic proportional operation valve that controls the noise shift pressure P s 46 But that has been set only et al.

The above-mentioned pilot pressure passage 31 is connected to the primary port of the electromagnetic proportional pressure reducing valve 46, and the secondary port is connected to the perforated pressure passage 47. After that, they are respectively communicated with the two outlet pressure control inlets 48 of the two regulator control valves 39 in the capacity control means 35.

This electromagnetic ratio reducing valve 46 controls the noise pressure, which is controlled by the relief valve 34, to the solenoid 45 from the controller 45. The proportional control in response to the electric signal to the node 49, and the regulator pressure 39 Each of the mechanical regulators 37 is guided to the force inlet 48 by controlling the displacement of the regulator valve 39 against the piston 50. The stroke 38 is controlled with high accuracy and the swash plate 36 is driven to a desired tilt angle.

Further, the pump discharge pressure of the main pump 11 is guided to the regulator control valve 39 of the capacity control means 35, and the main pump is discharged from the engine 13 by the main pump. As constant horsepower control means for uniformly controlling the pump horsepower supplied to the pump 11, the pump horsepower is supplied from the discharge passages of the two main pumps 11 through the valve 51. Each of the passages 52 drawn out through the passages is connected to another one of the regulator pressure introduction portions 53 of the two regulator control valves 39.

In addition, a control valve for controlling the hydraulic oil supplied from the main pump 11 to the various hydraulic actuators as a load. Negative contact port pressure generated due to the neutral state and fine operation state of 15 is guided to the capacity control means 35 to minimize the pump discharge flow rate. As a negative control means, each of the control valves 15 when each of the control valves 15 to 30 is in the neutral state and the fine operation state is in each state. A two-group center / noise passage 54 that can communicate with the evening tank 14 via the items 21 to 30, and the tank that communicates with the tank 14 Restrictors 57 are respectively provided with the relief valve 56 at the boundary with the cooling passage 55, and are drawn out from the upstream side of these restrictors 57. A negative control passage 58 is provided for each of the two regulator control valves 39 and a separate nozzle port pressure inlet 59. Communicated I'll. Each negative control passage 58 is provided with a pressure detector 60 for detecting a negative control pressure. These pressure detectors 60 are connected to the controller 45, respectively.

In this way, the mechanical regulator 37 can utilize the existing ones as they are, to provide negative control means, constant horsepower control means, and power shift. The signal pressure from the control means is led to a regulator control valve 39 of a nozzle-operated type, and the mechanical pressure is controlled by the regulator control valve 39. Activate the piston 38 on the gear 37 to control the tilt angle of the swash plate 36, and according to the tilt angle of the swash plate 36, the pump displacement capacity To control. '' '

Further, various detectors (sensors) are added to the pump discharge pressure detector 42, the engine rotation number detector 44, the swash plate position detector, and the like. The operation amount detector detects the operation amount of the operation lever, the flow amount detector detects the pump discharge flow from the main pump 11, and the hydraulic actuator. (D) A load pressure detector for detecting the load pressure of the night is installed as necessary, and the output of these detectors is used as a control information signal as a control information signal. Input to the controller 45.

Next, the contents of the control port 45 will be described.

As shown in FIG. 2, the pump control system is roughly divided into a hydraulic circuit control unit 61, an engine speed control unit 62, and a main pump control system. It is equipped with three modules with the loop control unit 63, and will be described. The hydraulic circuit control section 61 determines whether or not the hydraulic oil temperature signal TEMP of the hydraulic oil, the operation of the hydraulic shovel for the front working machine, and the operation of the joystick for turning are operated. The detection signal SW i HI from the impulse switch for detection and the operation of the traveling travel lever are detected. The required flow rate Q required by the hydraulic circuit is calculated based on the detection signal SWtr from the travel switch.

The engine speed control section 62 includes a control state determination section 64, an under speed control torque calculation section 65, and an engine stop prevention section. It has a torque calculation section 66 and a main pump allowable torque calculation section 67, and has power mode PM, work mode WM, and access mode. The engine setting rotation speed N ac set by the dial, the engine rotation speed N detected by the engine rotation speed detector 44 The high pressure side is selected by the shuttle valve 41 and the pump discharge pressure Pp detected by the pump discharge pressure detector 42 is based on the pump discharge pressure Pp and the like. The magnitude of the torque available in the main pump 11, that is, the main pump allowable torque T mpal low is determined. .

The control status determination unit 64 is connected to each of the operation units 65 to 67, and controls the engine speed. Whether it is necessary to activate the engine prevention function based on various signals input from the engine rotation speed sensor, etc. Or an engine that keeps the engine speed close to the rated speed It has a function to determine the control status, such as whether or not the speed control needs to be activated.

As shown in FIG. 3, the underspeed control torque calculation section 65 has a rated rotation speed and a rated horsepower, as shown in FIG. It is stable because it is located at the discontinuous point of the boundary between the governor area controlled by the antenna and the uncontrolled lugging area. The under speed amount N us is set to secure the operation, and the under speed amount N us is less than the rated speed. In order to use the engine speed as the target speed, the target speed is set to the underspeed in the luggage area of FIG. 3, that is, the underspeed amount N. It operates under speed control torque to move to the left only by us, and it is set by access dial. The set rotation number, Rere Ru and with your good beauty-et-down di down times rotation number detector 44 d down di down times rotation number of the incoming LSE issue that has been detect in.

Basically, in order to realize the underspeed control of the engine 13, the regulator 37 of the main pump 11 is controlled. Then, the main pump 11 absorbs the load from the engine output torque in the form of (pump discharge pressure) X (pump discharge flow). It controls the torque, that is, the pump absorption torque.

The engine torque calculation unit 66 for preventing the engine from stalling, based on the engine rotation speed detected by the engine rotation speed detector 44, detects the air load. Engine protection to prevent engine shutdown Calculate the stop torque.

In addition, the main pump allowable torque calculating section 67 includes an acceleration torque set by an access dial and a standard speed. The under-speed control torque output from the control torque calculation unit 65 and the under-speed control torque output from the engine torque prevention calculation unit 66 are output. Based on the torque preventing torque, a main pump allowable torque Tmpa110w that can be used by the pair of main pumps 11 is determined.

As shown in FIG. 4, the main pump allowable torque operation section 67 uses the standard pump required for the main pump 11 of the rated rotation speed. To the torque T t, the entry prevention torque T as calculated by the aforementioned entry prevention torque calculation section 66 is subjected to a calculation process by an adder 71. Thus, the static torque T s is calculated, and the acceleration torque T ac is subjected to the power torque calculation by the power calculator 72 on the static torque T s. The dynamic torque Td is calculated by the following equation, and the dynamic torque Td is calculated by the under speed control torque calculating section 65 described above. The underspeed control torque T mp is processed by the adder 73 to calculate the main pump allowable torque T mpallow, which is calculated as follows. Main pump tolerance The torque Tmpal low is output to the main pump control unit 63.

In the main pump control section 63, as shown in FIG. 5, the required flow rate Q (%) output from the hydraulic pressure circuit control section 61 as shown in FIG. Is calculated by the torque converter 74 at the first break point pressure (the pump discharge pressure-flow rate characteristic shown in FIG. 6). Using the pump discharge pressure at the first break point, it is converted to the main pump request torque T mpreq (%), and the main pump request is calculated. Requests the torque T mpreq to the engine speed control unit 62.

This main pump request torque T mpreq is a torque required from the pump side which is determined according to the load state of the main pump 11. On the other hand, the main pump allowable torque T mpa 11 ow (%) is the allowable torque according to the load situation on the engine 13 side. Yes, and the lower torque of these main pump request torque T mpreq and the main pump allowable torque T mp a 110 w Is the pump absorption torque actually used by the main pump 11.

Further, the main pump allowable torque T mpal low output from the engine speed control unit 62 and the main pump request torque The torque T mpreq is input to the torque selecting means 75, and the smaller torque is selected. That is, the pump absorption torque is determined, and the pump absorption torque is obtained. The torque is converted to a first break point pressure by a converter 76, and the first break point pressure is further converted to a "one shift pressure Ps" by a converter 77. In addition, the converter 78 outputs the shift pressure P s from the electromagnetic proportional pressure reducing valve 46 in order to output the shift pressure Ps from the solenoid proportional pressure reducing valve 46. No. required in the head 49. ヮ Convert to the input signal (control current) Ips for single shift.

Therefore, as shown in FIG. When the shift input signal I ps is input to the solenoid 49 of the solenoid proportional pressure reducing valve 46, the calculated regulator is output from the solenoid proportional pressure reducing valve 46. The noise shift pressure signal Ps is output as the evening control pressure signal, and the regulator shift valve 39 is controlled by the noise shift pressure Ps. Under the control, the tilt angle of the swash plate 36 of the main pump 11 is controlled.

As described above, conventionally, pump control is performed by detecting the engine rotation speed.However, this control method uses the pump discharge pressure P p (or Detects the load pressure (actual load) and adds it to the control means, which is the same as the conventional mechanical regulator with a two-stage panel. It is possible to control the required horsepower of the pump while utilizing 37.

That is, by adding the pump discharge pressure detector 42 described above, the current two-stage non-rotation used in the pump control of the hydraulic pressure shovel is added. The pump discharge pressure Pp is detected from the drive section of the pump for controlling the pump swash plate by the pump. To make the P-Q characteristics ideal.ヮ By controlling the shift pressure P s, the error between the target control torque and the actual torque can be reduced.

In other words, as shown in FIG. 7, in the constant horsepower control means, the relationship between the pump discharge pressure PP and the pump discharge flow Q (hereinafter, referred to as the pump discharge flow Q) This relationship is called “pump P—Q characteristic”), and the regulation is controlled so that it changes on a specific constant pump horsepower curve. I control, but on the other hand, 9 In the shift control means, the controller 45 responds to the rotation speed deviation between the engine target rotation speed and the actual engine rotation speed. Calculate the pump absorption torque to be corrected and output the corresponding electrical shift signal I ps to control the electromagnetic ratio reducing valve 46. In this way, the shift pressure P s is controlled to shift the pump P-Q characteristic from a specific constant pump horsepower curve to another curve. As a result, the break point of the spring 50 used in the mechanical regulator 37 will be corrected, and the rotational speed deviation will be corrected. As shown in Fig. 7, when increasing the pump horsepower, the pump horsepower is shifted to the constant pump horsepower curve at the upper right.

Next, the operation of the embodiment shown in FIG. 1 will be described on the basis of the above control contents.

When all the stages 21 to 30 of the control valve 15 are in the neutral state and the fine operation state, the negative control means can be used to control the center noise. The negative control pressure generated on the upstream side of the restriction 57 of the path passage 54 is transferred to the negative control passage 58 through the negative control passage 58. It is guided to the pilot pressure introduction part 59 of the regulator control valve 39, and is regulated by the regulator 37 so that the pump discharge flow is minimized. The swash plate 36 is controlled.

Further, when the negative control pressure decreases due to the displacement of the stems 21 to 30, when the negative control pressure is reduced, the leg control passes through the passage 52 of the constant horsepower control means. Overnight, the regulator is regulated by the pump discharge pressure P p guided to the neurot pressure introduction part 53 of the control valve 39. By controlling the control valve 39, the pump horsepower (or the pump absorption torque) supplied from the engine 13 to the main pump 11 becomes constant. Thus, the tilt angle of the swash plate 36 is controlled by the regulator 37. That is, as shown in FIG. 7, as the pump discharge pressure Pp changes, the pump discharge flow rate along one constant pump horsepower curve. The tilt angle of the swash plate 36 is controlled by the regulator 37 so that Q changes.

Further, the controller 45 calculates the detected engine rotation speed N and the noise shift pressure P s corresponding to the pump discharge pressure P p by the controller 45. An electromagnetic proportional pressure reducing valve 46 of the noise shift control means is controlled by a control signal as a result of the arithmetic operation, and the pilot pressure reduced by the electromagnetic proportional pressure reducing valve 46 is controlled. The pressure, that is, the power shift pressure Ps is led to the pipe outlet pressure inlet 48 of the regulator evening control valve 39, and the pump discharge pressure and discharge flow The swash plate 36 is controlled by a regulator 37 so that the characteristics can be optimally shifted. That is, in FIG. 7, the curve is shifted from one constant pump horsepower curve to another constant pump horsepower curve.

As described above, the conventional horsepower control is performed by detecting the engine rotation speed N and performing the feed knock control. The present control device also detects the pump discharge pressure Pp from the main pump U and incorporates it into a control information signal for controlling the capacity control means 35. Therefore, it is possible to reduce a change in the number of revolutions of the engine 13 in response to a sudden change in the load pressure.

In addition, without using expensive control devices, without significant system changes, and using the same hardware as the detected hardware, Only by taking the pump discharge pressure Pp as the control information signal, it is possible to realize a good pump control device while holding down the cost-up.

The present control method and control device can be applied not only to control of a swash plate type pump, but also to control of an oblique axis type pump having a similar mechanism. Potential for industrial use

The control method and the control device reduce a change in the engine speed in response to a sudden change in the load pressure of the variable displacement pump, and are used only for construction machinery. In addition, as long as the variable drive pump is driven by the engine, it can be applied to other work machines and stationary industrial machines.

Claims

the scope of the request

1. Detect the engine speed and

Detects pump discharge pressure from a variable displacement pump which is driven by an engine and has capacity control means for variably controlling the pump discharge flow rate.

A power shift pressure corresponding to the engine rotation speed and the pump discharge pressure is led to the capacity control means, and the pump discharge pressure of the variable displacement pump is reduced to one. Shift control to optimize discharge flow rate characteristics

A pump control method characterized by this.

2. Detect the engine rotation speed and

Detects pump discharge pressure from a variable displacement pump, which is provided with capacity control means driven by the engine and variably controls the pump discharge flow rate.

A negative valve generated by the neutral and fine operation of the control valve that controls the working fluid supplied to the load from the variable displacement pump Control pressure to the capacity control means to control the pump discharge flow to a minimum,

The pump discharge pressure is guided to the displacement control means, and the pump horsepower supplied from the engine to the variable displacement pump is controlled to be constant.

The power shift pressure corresponding to the engine rotation speed and the pump discharge pressure is led to the capacity control means to be a variable capacity type. Pump discharge pressure-Shift control with optimum discharge flow characteristics

A pump control method characterized by this.

3. Displacement control means for variably controlling the discharge flow rate of the variable displacement pump driven by the engine;

An engine rotation speed detecting means for detecting an engine rotation speed;

A pump discharge pressure detecting means for detecting a pump discharge pressure from the variable displacement pump;

A power shift pressure corresponding to the engine rotation speed and the pump discharge pressure is led to the capacity control means, so that the pump discharge pressure of the variable displacement pump — Know shift control means for shift control to optimize discharge flow rate characteristics

A pump control device characterized by having:

4. Displacement control means for variably controlling the discharge flow rate of the variable displacement pump driven by the engine;

A pump discharge pressure detecting means for detecting a pump discharge pressure from the variable displacement pump; and

The power shift pressure corresponding to the engine rotation speed and the pump discharge pressure is led to the capacity control means, and the pump discharge pressure of the variable displacement pump is reduced. A know shift control means for shifting and controlling the discharge flow characteristic optimally;

The pump discharge pressure is led to the capacity control means and the engine Constant horsepower control means for controlling the pump horsepower supplied to the variable displacement pump from the

A negative valve generated by the neutral and fine operation of the control valve that controls the working fluid supplied to the load from the variable capacity pump Negative control means for controlling the pump discharge flow rate to a minimum by guiding the control pressure to the capacity control means; and

A pump control device characterized by having:

5. The capacity control means

A swash plate for variably adjusting the pump discharge flow rate, and

A fluid pressure actuator for controlling the tilt angle of the swash plate; and a mechanical regulator for the swash plate.

The mechanical Regyu Yule is

A piston that operates by receiving a squeeze in the direction of increasing the tilt angle of the swash plate;

Regulated evening control valve with pipe opening that controls the piston in the direction to reduce the tilt angle of the swash plate by the fluid pressure that resists the non-force. When

The pump control device according to claim 3 or 4, wherein the pump control device is characterized by comprising:

6.ヮ The shift control means

A controller for calculating a know shift pressure corresponding to the engine rotation speed and the pump discharge pressure;

Noise that is input to the regulator control valve of the capacity control means in response to the electric signal output from the controller Electromagnetic proportional action valve for controlling the lot pressure

The pump control device according to claim 5, wherein the pump control device comprises: