JP3469980B2 - Boom swing hydraulic excavator - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boom swing type hydraulic excavator provided with a boom capable of swinging in the left and right directions, and more particularly to a boom swing type hydraulic excavator suitable for use as an ultra-small swing hydraulic excavator.

[0002]

2. Description of the Related Art Conventionally, for example, an actual Kaihei 4-46149 is used.
As described in Japanese Patent Publication, a boom swing hydraulic excavator has been proposed in which a boom is mounted on an upper swing body via a swing post, and a work machine is rocked in the left and right directions by operating a swing cylinder. There is.

A boom swing type hydraulic excavator of this type has a main body having an operator's cab, and a boom connected to the side of the operator's cab of the main body so as to be swingable in the left and right directions and vertically rotatable. An arm that is rotatably connected to the boom, a bucket that is rotatably connected to the arm, and an actuator that drives a work machine including the boom, the arm, and the bucket,
And a directional control valve for controlling the flow of hydraulic oil supplied to each actuator.

FIG. 7 is a hydraulic circuit diagram of a conventional boom swing hydraulic excavator, and FIG. 8 is a block diagram of a microcomputer provided in the boom swing hydraulic excavator of FIG. Figure 7
, 1 is a prime mover, 2 and 3 are main pumps and pilot pumps respectively driven by the prime mover 1, 4, 5
Are a boom cylinder and a swing cylinder as the actuators, 6 is a directional control valve for controlling the flow of hydraulic oil supplied from the main pump 2 to each actuator, 7 is a first pilot valve for performing a boom operation and a bucket operation, Reference numeral 8 is a second pilot valve for performing a turning operation and arm operation, and 9 is a swing pilot valve for performing a boom swing operation. These pilot valves 7
Reference numerals 9 to 9 respectively have a left chamber and a right chamber which communicate with the pilot pump 3, and the pressure oil discharged from the pilot pump 3 depends on an instruction signal from an operating means such as an operating lever. Supplied to the left or right chamber.
Other actuators such as other arm cylinders, bucket cylinders, traveling motors, etc. are not shown.

Further, the boom swing hydraulic excavator has a microcomputer 10 as a calculation means for calculating a positional relationship between the working machine and a driver's cab (not shown), and the microcomputer 1
A plurality of electromagnetic valves, for example, electromagnetic proportional pressure reducing valves 11 to 13 are provided as control means for controlling the rotating operation and the swinging operation of the working machine according to the calculation result of 0. Of these, the swing left electromagnetic proportional pressure reducing valve 11 is provided in the swing left pilot pipe line 14 that connects the swing pilot valve 9 and the direction control valve 6. The boom-raising electromagnetic proportional pressure reducing valve 12 is provided in a boom-raising pilot pipe line 15 that connects the first pilot valve 7 and the direction control valve 6. The arm-pulling electromagnetic proportional pressure reducing valve 13 is provided in an arm-pulling pilot conduit 16 that connects the second pilot valve 8 and the directional control valve 6. On the other hand, the other swing right pilot conduit 17, the boom lowering pilot conduit 18, and the arm pushing pilot conduit 19 are each directly connected to the directional control valve 6.

An emergency stop electromagnetic switching valve 20 controlled by the microcomputer 10 is provided on the discharge side of the pilot pump 3, and the electromagnetic switching valve 20 has a port connected to the tank. There is. This electromagnetic switching valve 20
Is switched by an emergency stop signal output from the microcomputer 10, and only when this emergency stop signal is input, the pilot conduit 21 connected to the discharge side of the pilot pump 3 is shut off and returned to the tank. There is.

As shown in FIG. 8, each angle signal θ is input to the microcomputer 10 from an angle detector 22 for detecting a relative angle of a working machine (not shown). The microcomputer 10 includes an angle calculation unit 23 that calculates the angle of the reference position of the working machine based on the angle signal θ, and an area storage unit 2 that stores a control data map such as a control area in advance.
4 and the relative angle calculated by the angle calculator 23 is determined whether or not the relative angle is within the control area stored in the area storage 24, and a predetermined control signal is output according to the result of the comparison. The calculation unit 25 and the drive control unit 26 that outputs a predetermined control signal to the solenoid valves 11 to 13 based on the control signal from the comparison calculation unit 25 are provided.

The swing left electromagnetic proportional pressure reducing valve 11 has a port connected to the tank and is operated in proportion to the current value of the control signal output from the drive control unit 26 of the microcomputer 10. Normally, when the swing left pilot conduit 14 is fully opened according to the maximum level current signal and the minimum level current signal is input as the control signal, the pressure oil in the swing left pilot conduit 14 is shut off and returned to the tank. When a current signal having an intermediate current value is input as the control signal, the pressure oil in the swing left pilot conduit 14 is throttled to reduce the pilot pressure. The same applies to the boom-raising electromagnetic proportional pressure reducing valve 12 and the arm-pulling electromagnetic proportional pressure reducing valve 13.

In the boom-swing hydraulic excavator constructed as described above, the control area determined in advance in accordance with the mutual relationship between the relative angle of the working machine and the swing angle is stored in the area storage unit 24 of the microcomputer 10 to calculate the angle. Based on the calculation result of the unit 23, it is determined by the comparison calculation unit 25 whether the position of the work machine with respect to the driver's cab is located in the control area, and when the work machine enters the control area,
By operating at least one of the electromagnetic proportional pressure reducing valves 11, 12, and 13 to control both or one of the rotating operation and the swinging operation of the working machine, it is possible to prevent interference between the working machine and the cab. It has become.

For example, when the working machine enters the control area in accordance with the swing left operation of the swing cylinder 5 and the swing left pilot pipeline 14 is shut off by the operation of the swing left electromagnetic proportional pressure reducing valve 11, the swing pilot is used. Even if the swing left operation of the valve 9 is performed, the directional control valve 6 is returned to the neutral position, so the swing left operation of the swing cylinder 5 is prohibited. The same applies when the working machine enters the control area due to the raising operation of the boom cylinder 4 or the arm pulling operation.

Further, in spite of the output of the operation command from the microcomputer 10, when one or both of the turning operation and the swinging operation of the working machine are continued due to the failure of any of the electromagnetic proportional pressure reducing valves 11 to 13, Since the microcomputer 10 outputs an emergency stop command, the emergency stop electromagnetic switching valve 20 operates in response to the emergency stop command. As a result, the pilot pressure supplied from the pilot pump 3 is reduced to the tank pressure, and all the directional control valves 6 are returned to the neutral position, so that all operations of the hydraulic excavator are stopped.

[0012]

By the way, in the conventional boom swing type hydraulic excavator described above, the microcomputer 10 is used.
Even if the swing left electromagnetic proportional pressure reducing valve 11 is operated by the output of the operation command from, the directional control valve 6 does not return to the neutral position due to, for example, a stick phenomenon or the like caused by the entrapment of foreign matter. Since the hydraulic oil is still supplied from the directional control valve 6 to the swing cylinder 5, there is a problem in that the swing left motion in which the boom approaches the cab cannot be stopped. Further, after the electromagnetic proportional pressure reducing valve 11 is operated, it is strongly influenced by the responsiveness of the directional control valve 6, so that the directional control valve 6 returns to the neutral position and the supply of hydraulic oil is blocked, and the swing cylinder 5 There was also a problem that it took time to stop.

Further, when a load is applied to the rod side of the swing cylinder 5 due to the weight of the working machine while the swing operation is stopped, internal swing of the directional control valve 6 causes the swing cylinder 5 to contract and the swing left operation is performed. , There was a concern that the boom would swing in a direction that interferes with the cab.
In particular, when the work machine is stopped in a state where the work machine is extended forward on a sloping ground, a large swing moment is applied to the work machine due to the weight of the work machine, and the swing cylinder 5 is provided at the base of the boom. As a result, a large load is applied to the swing cylinder 5, so that there is a problem that the boom swings in a direction in which it interferes with the operator's cab due to the internal leak of the directional control valve 6 described above.

The present invention has been made in view of the above-mentioned circumstances of the prior art, and an object thereof is to securely prevent interference between a swingable boom and a driver's cab and to provide a highly safe boom swing hydraulic pressure. To provide excavators.

[0015]

SUMMARY OF THE INVENTION According to the present invention, a control means controls a turning operation and a swinging operation of a working machine according to a positional relationship between a working machine and a driver's cab, and a direction from a swing cylinder for a boom is controlled. The hydraulic oil line returned to the control valve was closed by an operating check valve. As a result, for example, when the working machine swings toward the driver's cab and the swing angle exceeds a predetermined value, the swinging motion of the boom is controlled by the control means. At this time, even if the directional control valve sticks and does not return to the neutral position, the operating check valve closes the pipeline of the hydraulic oil returned from the swing cylinder to the directional control valve, so that the swing cylinder is quickly moved. Stop at. Furthermore, even when the load is applied to the swing cylinder due to the weight of the working machine while the swing operation is stopped, the return line from the swing cylinder to the directional control valve is closed by the operate check valve. The movement of the swing cylinder due to the internal leak of the directional control valve is prevented. Therefore, interference between the swingable boom and the driver's cab can be reliably prevented.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A boom swing hydraulic excavator according to the present invention comprises an angle detector for detecting a relative angle of a working machine, and the working machine and the working machine based on a detection value output from the angle detector. The swing cylinder for the boom and the direction include a calculation means for calculating the positional relationship with the cab, and a control means for controlling the rotation operation and the swing operation of the working machine according to the calculation result of the calculation means. Between the control valve and an operating check valve that opens and closes a pipeline of the hydraulic oil controlled by the control means and returned from the swing cylinder to the directional control valve, a relative angle between the working machine and the swing angle is provided. A control area determined in advance according to the mutual relationship is stored in the arithmetic means, and the position of the working machine with respect to the cab is controlled based on the arithmetic result of the arithmetic means. If the working machine invades the control area, it controls both or one of the rotating operation and the swinging operation of the working machine, and the control of the swinging operation at that time. At the time, the operating check valve closes the pipeline of the hydraulic oil returned from the swing cylinder to the directional control valve.

Further, the control means is composed of a plurality of solenoid valves for respectively reducing pilot pressures supplied to the directional control valve from a plurality of pilot valves for operating a rotating operation and a swinging operation of the working machine, and A pilot line for guiding the pilot pressure supplied from the swing pilot valve to the directional control valve to the operating check valve is provided, and the operating check valve is opened by a predetermined pilot pressure when the swing pilot valve is operated,
The operation check valve is closed by reducing the predetermined pilot pressure according to the control operation of the solenoid valve for swing.

Further, the operating check valve is provided in a hydraulic oil pipe line connecting the directional control valve and the rod side of the swing cylinder, and the swing solenoid valve is connected to the swing pilot valve and the directional valve. The swing left pilot conduit connected to the control valve was provided, and one end of the pilot conduit for guiding pilot pressure to the operate check valve was connected to the swing pilot valve side of the swing left pilot conduit.

[0019]

EXAMPLES Examples will be described with reference to the drawings.
1 is a hydraulic circuit diagram of a boom-swing hydraulic excavator according to an embodiment of the present invention, FIG. 2 is a circuit diagram illustrating a swing left action, and FIG. 3 is a circuit diagram illustrating a state in which the swing left action is stopped. 4 is a circuit diagram for explaining a state of the swing left electromagnetic proportional pressure reducing valve during operation. In FIGS. 1 to 4, the same components as those shown in FIGS. 7 and 8 described above are designated by the same reference numerals.

The boom swing hydraulic excavator of this embodiment shown in FIG. 1 is different from the conventional boom swing hydraulic excavator shown in FIG. 7 in that the rod side of the swing cylinder 5 and the directional control valve 6 are connected to each other. The main difference is that an operating check valve 28 is provided in the pipe line 27, and a pilot pipe line 29 that guides pilot pressure from the swing pilot valve 9 is provided in the operating check valve 28, and other configurations are almost the same. It is the same.

The operating check valve 28 opens the rod side pipe 27 when a predetermined pilot pressure is supplied from the swing pilot valve 9 so that the hydraulic oil returns from the swing cylinder 5 to the directional control valve 6. On the other hand, when the pilot pressure supplied from the swing pilot valve 9 is reduced, the rod side conduit 27 is closed to prevent the hydraulic oil from returning from the swing cylinder 5 to the directional control valve 6. Has become. Further, when the operating oil is supplied from the direction control valve 6 to the rod side of the swing cylinder 5, it is not obstructed by the operate check valve 28.

One end of the pilot conduit 29 is connected to the pilot valve 9 side of the swing left pilot conduit 14, and the pilot on the inlet side of the swing left electromagnetic proportional pressure reducing valve 11 is connected via this pilot conduit 29. Pressure is directed to the operate check valve 28.

In this embodiment, the swing left solenoid proportional pressure reducing valve 11 is operated in proportion to the current value of the control signal output from the drive control unit 26 of the microcomputer 10. For example, when the swing angle of the boom is within a predetermined value, the microcomputer 1
As shown in FIG. 2, the electromagnetic proportional pressure reducing valve 11 fully opens the swing left pilot conduit 14 in response to the maximum level current signal output from the drive control unit 26 of 0, so that the swing pilot valve 9 is operated. Accordingly, since the pilot pressure is supplied through the swing left pilot pipe line 14, the directional control valve 6 operates up to the stroke end, and the operate check valve 28 opens the rod side pipe line 27 of the swing cylinder 5. As a result, the hydraulic oil is supplied from the directional control valve 6 to the bottom side of the swing cylinder 5, and at the same time, from the rod side of the swing cylinder 5 to the rod side conduit 2
Since the hydraulic oil is returned to the directional control valve 6 via 7, the swing cylinder 5 extends and the swing left operation is performed.

Further, as shown in FIG. 3, when the swing pilot valve 9 is not operated, pilot pressure is not supplied through the swing pilot valve 9, so the directional control valve 6 does not operate and returns to the neutral position. Is being done,
The operate check valve 28 closes the rod-side conduit 27 of the swing cylinder 5, and the swing cylinder 5 is held in a stopped state.

When the boom is swung toward the driver's cab and the swing angle exceeds a predetermined value, the drive control unit 26 of the microcomputer 10 outputs a minimum level control signal. As shown, since the swing left electromagnetic proportional pressure reducing valve 11 is biased to the right and the swing left pilot conduit 14 is connected to the tank, the swing left pilot conduit 14 and the pilot conduit 2 are connected.
The pilot pressure in 9 is reduced. Along with this, the directional control valve 6 returns to the neutral position, and the operation check valve 28 closes the rod-side conduit 27 of the swing cylinder 5, so that the swing cylinder 5 stops.

In the embodiment thus constructed, when the working machine enters the predetermined control area and the swing operation is controlled by the operation of the swing left electromagnetic proportional pressure reducing valve 11, the directional control valve 6 sticks. Even if the swing cylinder 5 does not return to the neutral position, the operating check valve 28 closes the rod-side conduit 27 of the swing cylinder 5, so that the extension operation of the swing cylinder 5 is quickly stopped. Further, even when the swing cylinder 5 receives a load in the extension direction due to the weight of the work machine while the swing operation is stopped, the rod-side conduit 27 of the swing cylinder 5 is closed by the operation check valve 28. The extension operation of the swing cylinder 5 due to the internal leak of the directional control valve 6 is prevented. Therefore, interference between the swingable boom and the driver's cab can be reliably prevented.

In this embodiment, one end of the pilot conduit 29 is connected to the pilot valve 9 of the swing left pilot conduit 14.
Although the case where the pilot line 29 is connected to the side is illustrated, one end of the pilot line 29 is connected to the swing left pilot line 1 as shown in FIG.
4 or the branch pipe 30 branched from the swing left pilot conduit 14 is connected to the inlet of the electromagnetic proportional pressure reducing valve 11 as shown in FIG. At the exit side of 11, the pilot line 29
The same effect can be obtained by connecting one end of each.

Further, in the present embodiment, the open / close control of the operating check valve 28 is performed via the pilot pressure. However, an electric signal is directly input to the operating check valve 28 from the drive control section 26 of the microcomputer 10. The open / close control of the operating check valve 28 may be performed by an electric signal.

[0029]

As described above, according to the present invention,
Even when the directional control valve for swing does not return to the neutral position by sticking, the return line of the swing cylinder is closed by the operate check valve, so that the swing operation can be quickly stopped. Even when the swing cylinder is loaded by the weight of the work machine while the swing operation is stopped, the operation of the swing cylinder due to internal leakage such as the directional control valve is blocked by the operation check valve. It is possible to prevent the swinging motion of the boom in the direction in which it interferes with the cab. Therefore, interference between the swingable boom and the driver's cab can be reliably prevented, and a highly safe boom-swing hydraulic excavator can be obtained.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a boom swing hydraulic excavator according to an embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating a swing left action.

FIG. 3 is a circuit diagram illustrating a state in which a swing left action is stopped.

FIG. 4 is a circuit diagram illustrating a state during operation of a swing left electromagnetic proportional pressure reducing valve.

FIG. 5 is a circuit diagram showing a modified example of a pilot line provided in the boom swing hydraulic excavator of the present embodiment.

FIG. 6 is a circuit diagram showing another modification of the pilot conduit provided in the boom swing hydraulic excavator of this embodiment.

FIG. 7 is a hydraulic circuit diagram of a conventional boom swing hydraulic excavator.

FIG. 8 is a block diagram of a microcomputer included in the boom swing hydraulic excavator of FIG. 7.

[Explanation of symbols]

4 boom cylinder 5 swing cylinder 6 directional control valve 9 Swing pilot valve 10 Microcomputer (calculation means) 11-13 Electromagnetic proportional pressure reducing valve (control means) 14 Swing Left Pilot Line 22 Angle detector 27 pipelines 28 Operate check valve 29 Pilot pipeline

Continuation of front page (56) Reference JP-A 1-271536 (JP, A) JP-A 3-221628 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) E02F 3 / 43 E02F 3/32 E02F 9/22-9/24

Claims (3)

(57) [Claims] 1. A main body having a driver's cab, a boom connected to the side of the driver's cab of the main body so as to be swingable in the left-right direction and rotatable in the vertical direction, and rotatable with respect to the boom. An arm connected to the arm, a bucket rotatably connected to the arm, an actuator that drives a working machine including the boom, the arm, and the bucket, and a flow of hydraulic oil supplied to the actuator. In a boom swing hydraulic excavator equipped with a directional control valve for controlling, an angle detector that detects a relative angle of the working machine, and the working machine based on a detection value output from the angle detector. Equipped with a computing means for computing the positional relationship with the operator's cab, and a control means for controlling the turning operation and the swinging operation of the working machine according to the computation result of the computing means. ,
An operating check valve is provided between the boom swing cylinder and the directional control valve to open and close a pipeline of hydraulic oil controlled by the control means and returned from the swing cylinder to the directional control valve. Of the control unit is stored in the arithmetic means in advance according to the mutual relationship between the relative angle of the swing angle and the swing angle, and the position of the working machine with respect to the cab is based on the arithmetic result of the arithmetic means. Whether or not to do, when the working machine enters the control area, while controlling both or one of the rotation operation and the swing operation of the working machine, at the time of controlling the swing operation at that time, The booth is characterized in that the operating check valve closes the pipeline of hydraulic oil returned from the swing cylinder to the directional control valve. Musing type hydraulic excavator. 2. The plurality of control means according to claim 1, wherein the control means reduces the pilot pressures supplied to the directional control valve from a plurality of pilot valves that operate a rotating operation and a swinging operation of the working machine, respectively. And a pilot line for guiding the pilot pressure supplied from the swing pilot valve to the directional control valve to the operating check valve is provided, and the operating pressure is controlled by a predetermined pilot pressure when the swing pilot valve is operated. A boom swing hydraulic excavator characterized in that a check valve is opened, and the operating check valve is closed by reducing the predetermined pilot pressure according to a control operation of the electromagnetic valve for swing. 3. The operation check valve according to claim 2, wherein the operating check valve is provided in a hydraulic oil pipe line connecting the directional control valve and a rod side of the swing cylinder, and the swing solenoid valve is A pilot line that is provided in the swing left pilot line that connects the swing pilot valve and the directional control valve, and that guides pilot pressure to the operate check valve on the swing pilot valve side of the swing left pilot line. Boom swing type hydraulic excavator characterized by connecting one end of.