JPH05140968A - Revolving speed control device for prime mover of hydraulic construction machine - Google Patents

Abstract

PURPOSE:To enhance the functions in terms of the rate of fuel consumption, noise smoke emission, maneuvering feeling, etc., by increasing the engine revolving speed by a certain amount when an operating condition judging circuit judges that it is necessary. CONSTITUTION:An operating condition judging circuit 75 judges whether or not increase of the engine revolving speed is necessary on the basis of operation, if any, of each of the pilot valves corresponding to a plurality of hydraulic actuators and also of the operating direction of the pilot valve. The revolving speed set by an engine revolving speed setting device 57 is increased by a certain amount by a revolving speed correction device 74 in accordance with the operating condition judged by the operating condition judging circuit 75. Only in case it is necessary to increase the engine revolving speed in original sense, the setting device 57 is operated to make change of the setting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prime mover speed control device for a hydraulic construction machine.

[0002]

2. Description of the Related Art The present applicant has previously filed Japanese Patent Application Laid-Open No. 63-16704.
A prime mover speed control device as disclosed in Japanese Patent No. 2 has been proposed. This prime mover rotation speed control device increases the rotation speed of the prime mover according to the load to improve the fuel consumption rate and reduce noise.For example, the running pressure of a wheel type hydraulic excavator exceeds a predetermined value. At times, the engine speed is increased by a predetermined value.

[0003]

When such an engine speed control system is adopted for the front work of a hydraulic excavator, there are the following problems. The hydraulic excavator has a boom cylinder, an arm cylinder, a bucket cylinder, and a swing motor, and the pressure characteristics of each hydraulic actuator differ depending on the weight of each actuator, the link ratio, the pressure receiving area of the drive cylinder, and the like. For example, arm pulling work,
Bucket pulling work, the pressure at the time of no-load of the bucket press work is relatively low is 50kgf / cm ² ~100kgf / cm ² about.
On the other hand, the arm pressing work and driven by the rod side of the cylinder (small pressure receiving area), is relatively high pressures of about ² 150kgf / cm ² ~350kgf / cm even in the fine operation at no load with large rotary working of the inertial force Occur. Therefore, if the engine speed is set to increase when the pressure of the hydraulic pump reaches the pressure during excavation work in which the arm pulling work and the bucket pulling work are performed at the same time, for example, 200 kgf / cm ² , the increase in the rotation speed is supposed to occur. The engine speed also increases during unnecessary arm pushing work and turning work, which is not preferable in terms of fuel consumption, noise, smoke generation, and operation feeling.

An object of the present invention is to provide a prime mover speed control device for a hydraulic construction machine, which is capable of increasing the prime mover speed only in a working state in which the increase of the prime mover speed is required.

[0005]

To explain with reference to FIG. 1 showing an embodiment, a prime mover rotation speed control device according to the present invention operates each operating means corresponding to at least a plurality of hydraulic actuators. Based on the presence or absence of the engine and the operating direction, the determining means 75 determines whether or not the operating state requires the increase of the engine speed, and the determining means 75 determines the engine speed set by the engine speed setting means 57. A motor rotation speed correction means (74, 7) for increasing the determined motor rotation speed by a predetermined value in accordance with the required operating state.
6) is provided to achieve the above object. The apparatus of claim 2 further increases the number of revolutions of the prime mover according to the pump pressure. The apparatus according to the third aspect of the present invention determines the operating state by also considering the pump pressure. The apparatus of claim 4 is
Two or more kinds of operation states in which the prime mover rotation speed should be increased are set, and the rotation speed to be increased is made different according to each operation state.

[0006]

When the discriminating means 75 discriminates an operating state requiring an increase in the number of revolutions of the prime mover, for example, the number of revolutions of the prime mover set depending on the amount of operation of the fuel lever corresponds to the determined operating state. Is increased by a predetermined value. Further, the prime mover rotation speed is further increased according to the pump pressure. Further, when two or more operation states in which the prime mover rotation speed is to be increased are set and the optimum increase in the prime mover rotation speed for each operation state is set to a different value, which of the plurality of operation states is selected. It is determined whether it is in the operating state, and the engine speed is increased according to the determination result.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the purpose of making the present invention easy to understand. It is not limited to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a wheel type hydraulic shovel will be described with reference to FIGS. FIG. 2 is a diagram showing the overall configuration of a drive control device for a hydraulic construction machine according to the present invention. Reference numeral 1 is a variable displacement hydraulic pump driven by an engine (motor) 20. The rotation speed of the engine 20 is controlled by rotating the governor lever 20b of the governor 20a with the pulse motor 21. Then, the discharge oil of the variable displacement hydraulic pump 1 according to the engine speed is guided to the hydraulic motor 3 via the traveling control valve 2 and the boom hydraulic cylinder 5 via the boom control valve 4.
Be led to.

Reference numeral 6 is a pilot hydraulic pump driven by the engine 20, and 7 is a traveling pilot valve operated by a traveling pedal a. For example, the forward / reverse switching valve 8 is switched to forward (F position) pilot valve 7 When the pedal 7a is operated, the oil discharged from the pilot hydraulic pump 6 is guided to the pilot port 2a of the pilot type control valve 2, and the control valve 2 is switched by the stroke amount according to the pilot hydraulic pressure. As a result, the oil discharged from the variable displacement hydraulic pump 1 is supplied to the hydraulic motor 3 via the pressure compensating valve 9 and the control valve 2, and the vehicle runs. The speed of the vehicle depends on the depression amount of the traveling pedal 7a.

When the pedal 7a is released during traveling, the pilot valve 7 shuts off the pressure oil, and its outlet port communicates with the tank 10. As a result, the pressure oil acting on the pilot port 2a returns to the tank 10 via the forward / reverse switching valve 8, the slow return valve 11, and the pilot valve 7. At this time, since the return oil is throttled by the throttle of the slow return valve 11, the pilot control valve 2 is gradually switched to the neutral position and the vehicle is gradually decelerated.

When a boom hydraulic pilot valve (not shown) is operated, the hydraulic pilot type boom control valve 4 is switched by the pressure corresponding to the operation amount, and the oil discharged from the hydraulic pump 1 is supplied to the pressure compensating valve 12 and. It is guided to the boom hydraulic cylinder 5 via the control valve 4, and the boom is moved up and down by the expansion and contraction of the hydraulic cylinder 5. Here, the pressure compensation valves 9, 12
Is for independently compensating the operation of the hydraulic motor 3 and the hydraulic cylinder 5 so that the hydraulic pump 1 supplies a pressure higher than the respective load pressures by a predetermined pressure.

When the hydraulic excavator is used for excavation work, an arm cylinder, a bucket cylinder and a swing motor are mounted in addition to the boom cylinder. When the hydraulic excavator is used as a crusher, the bucket cylinder swings the crusher. , The crusher actuator is connected to the preliminary control valve. When used as a vibro, the bucket cylinder is not in use, and the vibro actuator is connected to the preliminary control valve. Each of these cylinders,
Like the boom cylinder, the actuator such as the motor is driven through each control valve operated by the pilot pressure generated by the operation of the corresponding hydraulic pilot valve.

The tilt angle of the variable displacement hydraulic pump 1, that is, the displacement volume, is controlled by a tilt angle control device 40.
The tilt angle control device 40 controls the piston position by the hydraulic pump 41 driven by the engine 20, the pair of electromagnetic valves 42, 43, and the pressure oil from the hydraulic pump 41 according to the switching of the electromagnetic valves 42, 43. The servo cylinder 44 is configured to control the tilt angle of the hydraulic pump 1 according to the piston position of the servo cylinder 44. Here, the pair of solenoid valves 42 and 43 is switch-controlled by the controller 50.

Reference numeral 51 is a tilt angle sensor for detecting a tilt angle θs of the hydraulic pump 1, and 52 is a discharge pressure Pp of the hydraulic pump 1.
Is a pressure sensor, 53 is the engine speed N of the engine 20.
A rotation speed sensor for detecting r, 54 is a discharge pressure of the hydraulic pump 1 and a maximum load pressure of the actuator (the hydraulic motor 3
Is the larger of the load pressure of the hydraulic cylinder 5 and the load pressure of the hydraulic cylinder 5, which is the one selected by the shuttle valve 13, that is, the LS differential pressure ΔPLS. Further, 55 is a potentiometer that detects the amount of rotation Nθ of the governor lever 20b, and 56 is a pilot pressure sensor group that detects each pilot pressure for operating the actuators of the above-mentioned cylinders and the like. Is input to the controller 50. Reference numeral 57 is a rotation speed setting device that commands a target rotation speed X in accordance with a manual operation of the fuel lever 57a, and the command signal thereof is also input to the controller 50.

FIG. 3 is a diagram showing the details of the pilot pressure sensor group 56 for detecting each pilot pressure described above. 56a is a pilot pressure sensor on the boom raising side, 5
6b is a boom lowering side pilot pressure sensor, 56c is an arm pulling side pilot pressure sensor, 56d is an arm pushing side pilot pressure sensor, 56e is a bucket pulling side pilot pressure sensor, 56f is a bucket pushing side pilot pressure sensor, 56g is a pilot pressure sensor that detects the swing pilot pressure, 56h is a pilot pressure sensor that detects the traveling pilot pressure, and 56i is a pilot pressure sensor that detects the crusher pilot pressure, for example.

As shown in FIG. 4, the controller 50 has a tilt angle control circuit 60 for controlling the pump tilt angle, and this control circuit 60 is a load sensing control unit (hereinafter referred to as LS).
Control unit) 61, torque control unit 62, and minimum value selection unit 6
3 and a servo control unit 64.

The LS control section 61 controls the target differential pressure ΔPLSR1.
Of the differential pressure ΔPLSD detected by the differential pressure sensor 54 and the deviation Δ (PLS) from the target differential pressure are calculated by the deviation device 61b, and a function is generated based on this deviation Δ (PLS). The change amount ΔθL of the target value is calculated by the unit 61c. Further, the change amount ΔθL of the target value is integrated by the integrator 61d to obtain the target pump tilt angle θ for the load sensing control.
Output as L.

The torque control unit 62 is a target torque calculation unit 62.
The target torque calculation unit 62a has a torque calculation unit 62a that calculates the torque Tr exerted by the engine from the governor lever position Nθ detected by the potentiometer 55, and the engine speed Nr detected by the rotation speed sensor 53. And a deviation ΔT between the governor lever position Nθ detected by the potentiometer 55 and the deviation ΔT are added to the torque Tr to calculate a target torque Tpo. Reciprocal calculation unit 62b
Is supplied with the pump discharge pressure detected by the pressure sensor 52, and calculates the reciprocal 1 / P corresponding to the pressure. This reciprocal 1 / Pp is multiplied by the target torque Tpo in the multiplier 62c, and thereby θp is obtained (∵Tpo = θp ·
Pp). Further, this θp is set to the filter 6 of the first-order delay element
It is output as the target pump tilt angle θT for the input torque limit control over 2d.

The minimum value selector 63 selects the smaller one of the two target tilt angles θL and θT and inputs it to the servo controller 64 as the tilt angle command value θr. In the servo control unit 64, the deviation Δθ between the input tilt angle command value θr and the tilt angle feedback value θs detected by the tilt angle sensor 51 is calculated by the deviation device 64a, and this deviation Δθ is obtained. Based on this, the function generator 64b outputs ON / OFF signals for the solenoid valves 42 and 43. As a result, the tilt angle control device 40 is controlled so that the pump tilt angle θs matches the tilt angle command value θr.

Here, according to the load sensing control by the LS controller 61, the displacement volume of the variable displacement hydraulic pump 1 is controlled so that the LS differential pressure becomes a constant value, and the pump pressure is less than the load sensing pressure. Is also kept high by a predetermined target value, the pump tilt angle is controlled so that the pump discharge flow rate becomes the required flow rate of the control valve 2 or 4, and the excess flow rate is not discharged, resulting in waste due to throttling loss. Fuel efficiency and operability can be improved. Further, according to the input torque control by the torque control unit 62, the hydraulic pump 1
Is maintained within the range of the output torque of the engine 20, and the engine 20 is prevented from being overloaded.

Further, the controller 50 has an engine speed control circuit 7 for controlling the engine speed as shown in FIG.
Has 0. The function generator 71 outputs the target rotation speed Nx based on the rotation speed command value (the operation amount of the fuel lever 57a) x sent from the rotation speed setting device 57, and the function generator 72 outputs from the traveling pilot pressure sensor 56h. The target rotation speed Nt is output according to the traveling pilot pressure Pt sent. The maximum value of these target speeds is selected by the maximum value selection circuit 73 and input to the adder 74.

An operation state determination circuit 75 inputs each pilot pressure from the above-mentioned pilot pressure sensor group 56 and determines the operation state based on whether or not the operation lever is operated and the operation direction. Reference numeral 76 is shown in FIGS.
Is a map unit including three types of rotation speed correction maps A, B, and C, and each map stores the correction rotation speed ΔNc according to the input pump pressure as a map. The outputs of the maps A, B and C are respectively connected to the contacts a, b and c of the switch 77, and the switch 77 is operated by the operation state determination circuit 7
It is switched to any one of ac depending on the discrimination result in 5.

The output ΔNc of the switch 77 is added to the output Ny of the maximum value selection circuit 73 by an adder 74, and the deviation 78
The deviation from the governor lever position Nθ is taken by the deviation device 78, and when the deviation ΔN is equal to or larger than a predetermined value on the positive side, the function generator 79 gives a signal to the pulse motor 21 in the positive rotation direction, and the deviation ΔN Is less than or equal to a predetermined value on the negative side, the function generator 79 gives a signal in the reverse rotation direction to the pulse motor 21.

The operation state discriminating circuit 75 outputs pilot pressures corresponding to the actuators from the pressure sensors 56a to 56a.
As shown in FIG. 6, a flag provided corresponding to each pilot pressure is set to 1 when the corresponding pilot pressure is equal to or higher than a predetermined value, and is set to 0 when the pilot pressure is equal to or lower than the predetermined value. Is reset to. Then, a rotation speed correction map is selected from those shown in FIGS. 5A to 5C based on those flags. The predetermined value may be different for each operation lever.

Here, the map A is for the case where the engine speed correction amount is zero, and is selected, for example, during arm pushing work or turning work. Map B is selected, for example, when pulling the arm, and the pump pressure is 150 kgf / cm.
^When it exceeds ² , the engine speed is gradually increased by 200 rpm, and when the pump pressure becomes 125 kgf / cm ² or less, the increase in the engine speed is gradually reduced to zero. The map C is selected, for example, during excavation work in which arm pulling work and bucket work are performed simultaneously, simultaneous operation of arm pulling and running, or when the crusher is used. When the map C is selected, the engine speed is increased by 100 rpm regardless of the pump pressure, and when the pump pressure exceeds 200 kgf / cm ² , the engine speed is gradually increased to 5 rpm.
Increased by 00 rpm, pump pressure is 175kgf / cm ²
Under the following conditions, gradually increase the engine speed by 100 r
pm.

Next, the operation of the embodiment configured as described above will be described for the case where the bucket work is performed by setting a desired engine speed with the fuel lever 57a.
The maximum value selection circuit 73 in FIG. 1 outputs the engine speed Nx output from the function generator 71 as Ny. When you operate the arm pilot valve and push the arm,
As you can see from Figure 6, the arm push flag is set,
The operation state determination circuit 75 outputs a signal for selecting the map A to the switch 77, and the switch 77 is connected to the contact a. As a result, the map unit 76 outputs the map A signal to the switch 77. Since the corrected rotation speed ΔNc output from the map A is zero regardless of the pump pressure, the adder 74 outputs the rotation speed N commanded by the fuel lever 57a.
The y is output to the deviation device 78. Then, the deviation device 78 outputs a deviation from the actual rotation speed Nθ from the potentiometer 55 to the function generator 79, and the pulse motor 21 controls the engine governor so that the engine rotation speed becomes Ny.

When the arm pulling operation is performed, the arm pull flag is set as shown in FIG. 6, the operation state judging circuit 75 outputs a signal for selecting the map B to the switch 77, and the switch 77 is connected to the contact b. It As a result,
The map unit 76 outputs the signal of map B to the switch 77. Here, in Map B, the pump pressure is 150 kgf / cm ²
When it exceeds, the correction rotation speed ΔNc that gradually increases the engine rotation speed by 200 rpm is output, and the correction rotation speed ΔNc at which the pump pressure becomes 125 kgf / cm ² or less is gradually reduced to zero. Therefore, the adder 74 outputs the added value of the corrected rotation speed ΔNc output from the map B and the engine rotation speed Ny to the deviation device 78 according to the pump pressure, and the pulse 21 sets the engine rotation speed to Ny + ΔNc. It

When the arm pulling work and the bucket pulling work are performed at the same time, the arm pulling flag and the bucket pulling flag are set as shown in FIG.
5 outputs a signal for selecting the map C to the switch 77,
The contact 77 is connected to the switch 77. As a result, the map unit 76 outputs the map C signal to the switch 77. Here, since the map C outputs 100 rpm as the corrected rotation speed ΔNc regardless of the pump pressure, the engine rotation speed is set to 100 rpm + Ny output from the adder 74. In Map C, the pump pressure is 200 kgf /
When it exceeds cm ² , the correction rotation speed ΔNc that gradually increases the engine rotation speed by 500 rpm is output, and the correction rotation speed ΔNc at which the pump pressure becomes 175 kgf / cm ² or less is gradually reduced to 100 rpm. Therefore, the adder 7
4 outputs the added value of the corrected rotational speed ΔNc output from the map C and the engine rotational speed Ny to the deviation device 78 according to the pump pressure, and the pulse motor 21 sets the engine rotational speed to Ny + ΔNc.

The correction of the engine speed at the time of other work is shown in FIG.
As can be seen, the turning is based on the map A, and the combined operation of the arm pulling work and the traveling work is based on the map C.
The operation of the crusher is performed based on the map C, respectively. Note that the relationship between each work and the selected map and the correction amount of the prime mover rotation speed by the map are not limited to those in the embodiment.

In the construction of the above embodiment, the traveling hydraulic motor 3, the working cylinder 5 and the like serve as hydraulic actuators, the traveling pedal 7a and the pilot valve 7 serve as operating means, and the traveling control valve 2 and the boom control valve. 4 and the like constitute a control valve, the operation state discriminating circuit 75 constitutes a discriminating means, and the adder 74 and the map portion 76 constitute a rotational speed correcting means. Further, for example, the rotation speed setting device 57 that sets the target rotation speed according to the operation amount of the fuel lever 57a constitutes the rotation speed setting means.

Although the wheel type hydraulic excavator has been described above, the present invention can be applied to various hydraulic construction machines other than this. Further, although the load-sensing control type hydraulic control device has been described, the present invention is not limited to this. Further, the case where the variable displacement hydraulic pump is mounted has been described, but the present invention can also be applied to a hydraulic device equipped with a fixed displacement hydraulic pump. In addition, the case where the pilot pressure sensor is used to determine the operation of each operation lever has been described. However, when the control valve is configured to be driven by an electric lever, for example, the operation state is determined by the output signal from the electric lever. You may.

[0032]

According to the present invention, it is judged whether or not the operating state requires the increase of the number of revolutions of the prime mover based on the presence or absence of the operation of the operating means corresponding to each actuator and the operating direction, and the result of the determination. Since the prime mover rotation speed is increased in accordance with the above, the prime mover rotation speed is not increased during an undesired operation, such as when the rotation speed is simply increased or decreased when the pump pressure is equal to or higher than a predetermined value. Noise, smoke,
The operation feeling is improved. Further, if the rotation speed of the prime mover is increased in accordance with the pump pressure, the prime mover can be operated at a rotation speed more suitable for the work, which is more effective in terms of fuel consumption and noise. Furthermore, if two or more operation states are discriminated and the rotation speed is increased optimally for each operation state, it is further advantageous in terms of fuel consumption, noise, smoke generation, and operation feeling.

[Brief description of drawings]

FIG. 1 is a block diagram showing details of an engine speed control circuit of a prime mover speed control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing the overall configuration of a hydraulic construction machine.

FIG. 3 is a diagram showing details of a pilot pressure sensor group.

FIG. 4 is a block diagram showing details of a torque control unit.

FIG. 5 is a diagram illustrating a map section of a rotation speed control circuit.

FIG. 6 is a diagram illustrating an operation state determination circuit of a rotation speed control circuit.

[Explanation of symbols]

1: Variable capacity hydraulic pump 2: Travel control valve 4: Boom control valve 5: Boom cylinder 3: Travel hydraulic motor 7: Pilot valve 20: Engine (motor) 21: Pulse motor 40: Tilt control device 50: Controller 52: Pressure sensor 53: Rotation speed sensor 55: Potentiometer 56: Pilot pressure sensor group 57: Rotation speed setting device 57a: Fuel lever 70: Engine rotation speed control circuit 75: Operation state determination circuit 76: Map portion

Claims (4)

[Claims] 1. A hydraulic pump driven by a prime mover, a plurality of hydraulic actuators driven by oil discharged from the hydraulic pump, and a flow rate and a direction of pressure oil from the hydraulic pump to the plurality of hydraulic actuators, respectively. A plurality of control valves for controlling and a plurality of hydraulic actuators are provided respectively, and when operated in a first operation direction, the pressure oil is caused to flow in a first direction and operated in a second operation direction. And driving the control valves so that the pressure oil flows in the second direction,
A prime mover rotation speed control device comprising a plurality of operating means for controlling the flow rate of the pressure oil according to the operation amount in each operation direction, and a rotation speed setting means for setting the rotation speed of the prime mover, at least the operating means Based on the presence or absence of each operation and the operating direction, the determining means for determining whether or not the operating state requires an increase in the prime mover rotation speed, and the prime mover rotation speed set by the prime mover rotation speed setting means, A prime mover rotation speed control device for a hydraulic construction machine, comprising: a prime mover rotation speed correction means for increasing a predetermined value in accordance with the operation state judged by the judging means. 2. The apparatus according to claim 1, further comprising a pressure detection unit that detects the pressure of the hydraulic pump, wherein the motor rotation speed correction unit is determined based on the presence or absence of the operation and the operation direction. An engine speed control device for a hydraulic construction machine, wherein the engine speed is increased according to the operating state, and the engine speed is further increased when the detected pressure is equal to or higher than a predetermined value. 3. The apparatus according to claim 1, further comprising a pressure detection unit that detects the pressure of the hydraulic pump, wherein the operation state determination unit determines whether or not the operation is performed, the operation direction, and the detected pressure. A prime mover rotation speed control device for a hydraulic construction machine, which determines whether or not the operating state requires an increase in the prime mover rotation speed based on the above. 4. The apparatus according to claim 1, wherein the operating state determined by the determining means includes two or more states in which an increase in the number of revolutions of the prime mover is required, and the operating state should be increased corresponding to each operating state. A prime mover rotation speed control device for a hydraulic construction machine, which is characterized by different rotation speeds.