JPH1030257A - Locking device for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent such a situation that a hydraulic actuator operating various portions of a machine is driven although an operator has no intention to move the machine. SOLUTION: A solenoid selector valve 53 is provided on a delivery side passage 54 of a pilot pump 52, the passage 54 is normally closed, and the passage 54 is opened when a solenoid pilot part 53a is excited. Two switches 57, 58 are provided on a power feed line 56 to the solenoid pilot section 53a, and the switch 57 is turned on or off by a lever extended from a pivotal support section at the base end section of a lock lever 51. The switch 58 is turned on or off according to the load of a driver's seat 50. When the lock lever 51 is located at the aisle closing position hindering the alighting/boarding of an operator facing the alighting/boarding aisle of an operator's cab, the switch 57 is turned on. When the lock lever 51 is located at the aisle opening position, the switch 57 is turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock device provided in a hydraulic shovel or other construction machine so that the drive control of each hydraulic actuator provided in each section can be performed only under a set condition. It is about.

[0002]

2. Description of the Related Art A typical example of a construction machine is a hydraulic shovel. As shown in FIG. 4, the hydraulic excavator is provided with an upper revolving unit 2 rotatably provided on a lower traveling unit 1. The upper revolving unit 2 is provided with a front working mechanism 3. 4 and a machine room 5 are provided. The front working mechanism 3 includes a boom 6 which is connected to the frame of the upper swing body 2 so as to be capable of raising and lowering;
The arm 7 is provided at the end of the arm 7 so as to be rotatable in the vertical direction, and the bucket 8 is connected to the end of the arm 7 so as to be rotatable and is provided as a front attachment. The front working mechanism 3 including the boom 6, the arm 7, and the bucket 8 is driven by a hydraulic cylinder. The traveling by the lower traveling body 1 and the turning of the upper revolving superstructure 2 are driven by a hydraulic motor.

As described above, the hydraulic shovel is provided with various operating portions, and each of these operating portions is driven by a hydraulic actuator including a hydraulic cylinder and a hydraulic motor. Therefore, a hydraulic circuit diagram for performing drive control of each of the hydraulic actuators is generally as shown in FIG.

[0004] In the drawings, reference numerals 10a and 10b denote variable displacement hydraulic pumps.
0b is driven by the engine 11. Hydraulic pump 10
a, the direction switching valve unit 1
2a and 12b are provided, and the operation of the hydraulic actuator is controlled by a plurality of direction switching valves 13 constituting the direction switching valve units 12a and 12b.

The hydraulic actuators controlled by the respective directional control valves 13 include a boom cylinder 14, an arm cylinder 15, and a bucket cylinder 16, and left and right traveling motors 17a, 17b and a turning motor 18. Among these, the boom cylinder 14 and the arm cylinder 15 are configured to merge the pressure oil supplied from both the hydraulic pumps 10a and 10b. One directional control valve in the directional control valve unit 12b is used for supplying pressure oil to these actuators when a breaker or a crusher is used as a front attachment.

The hydraulic pumps 10a and 10b are of a variable displacement type whose discharge flow rate changes in accordance with the load.
9a and 19b are attached to each of the hydraulic pumps 10a and 10b.
Throttles 20a, 2b downstream of the direction switching valve units 12a, 12b in the center bypass flow path in the hydraulic circuit including
0b is provided, and the pressure on the upstream side of the throttles 20a, 20b is taken into the pump regulators 19a, 19b. Therefore, according to the return flow rate flowing through the center bypass flow path, the hydraulic pump 1
The discharge flow rates of 0a and 10b will change.

The directional control valves 13 constituting the directional control valve units 12a and 12b are operated by operating means such as operating levers and operating pedals. FIG. 5 shows, for simplicity, a bucket cylinder 1 as an example of an operating means.
An operating means 21 for controlling the directional control valve 13 connected to 6 is shown. The operating means 21 includes a pilot valve 22
Are connected, and this operating means 21 is indicated by an arrow A or B
By tilting in the direction, the pilot pressure from the pilot pump 23 is supplied to the hydraulic pilot portion 13a or 13b of the direction switching valve 13. For example, operating means 2
When 1 is tilted in the direction of arrow A, pilot pressure is supplied to the hydraulic pilot portion 13a of the direction switching valve 13, and the direction switching valve 13 switches from the neutral position to one of the switching positions. As a result, the hydraulic pump 10a communicates with the bottom chamber of the bucket cylinder 16, and the rod chamber communicates with the hydraulic oil tank 24, so that the bucket cylinder 16 extends. On the other hand, when the operating means 21 is tilted in the direction indicated by the arrow B, pilot pressure is supplied to the hydraulic pilot portion 13b of the direction switching valve 13 and the direction switching valve 13 switches to the other switching position. Will shrink.

The operating means is provided in the cab 4.
Therefore, a schematic configuration of the cab 4 is shown in FIG. As is apparent from this figure, a driver's seat 25 on which an operator sits is mounted in the driver's cab 4, and console boxes 26 (one console box in the drawing) are provided on both left and right sides of the driver's seat 25. Only the console lever 26 is provided.
7 are provided. A plurality of operation pedals 28 are provided on the floor in front of the driver's seat 25.
Accordingly, the operator operates the operating means including the operating lever 27 and the operating pedal 28 while sitting on the driver's seat 25, thereby driving the respective hydraulic actuators provided in the respective operating portions constituting the hydraulic shovel. it can.

Here, the operating lever 27 and the operating pedal 2
8 is always in a neutral position, and is operated so as to be tilted in one direction or the opposite direction from this state. At the neutral position of the operating means, the direction switching valve 13 is also at the neutral position,
In this state, no pressure oil is supplied to the hydraulic actuator. When tilted in one direction, the direction switching valve 13 switches. For example, in the case of a hydraulic cylinder, it expands, and in the case of a hydraulic motor, it rotates to the right, and when tilted in the opposite direction, the hydraulic cylinder contracts. Then, the hydraulic motor operates to rotate to the left. Therefore, even if the hydraulic pumps 10a and 10b are driven by the engine 11, if all the operation levers 27 and the operation pedals 28 are held at the neutral positions, the operation of all the hydraulic actuators stops, and the hydraulic shovel stops. Held in state. The oil discharged from the hydraulic pumps 10a and 10b is returned to the tank through the center bypass passage.

During the operation of the engine 11, if the operator is away from the cab 3, the lower traveling body 1,
It is necessary to surely stop the operation parts constituting the upper swing body 2 and the front working mechanism 3. Operator cab 3
When exiting from the vehicle, in an ordinary state, the operating means consisting of the operating lever 27 and the operating pedal 28 is kept at the neutral position, but it is absolutely unlikely that any of these operating means will move for some reason. I can not say. Therefore,
When the operator leaves the cab 3, a lock device that locks the operating parts so as not to move even if any of the operation means moves is conventionally used. That is, a lock lever 29 as a lock member is provided in the cab 3, and this lock lever 29 is arranged so as to face the passage for getting on and off, and as shown by a solid line in FIG. As shown by the imaginary line in the figure, the robot is pivoted upward to be displaceable between the blocking position and the passage opening position.

As a specific configuration of this type of lock device, for example, Japanese Unexamined Utility Model Publication No. 6-57964 and Japanese Unexamined Utility Model Application Publication No.
No. 7560, Japanese Utility Model Laid-Open No. 6-76459, and the like. Of these, the one disclosed in Japanese Utility Model Laid-Open No. 6-57964 is exemplified as shown in FIG. That is, the console box 30 provided in the operator's cab is made rotatable in the front-rear direction. A shut-off switch 31 that is turned on and off in accordance with the rotation of the console box 30 is provided. An off valve 33 is provided. The shut-off valve 33 is of an electromagnetic switching type, and is provided with a power supply 34 for energizing the electromagnetic pilot portion 33a, and the above-described shut-off switch 31 is provided on a power supply line 35 from the power supply 34. Have been.

A lock lever 36 is provided in the passage for the operator to get on and off, and a gate drive cylinder 37 is connected to the lock lever 36. The gate driving cylinder 37 is normally held at a position where the lock lever 36 opens the passage for getting on and off, as indicated by the imaginary line in the figure, and the pressure oil from the hydraulic pump 32 is driven by the gate driving cylinder. Is supplied to the cylinder 37 for
As shown by the solid line, the lock lever 36 is displaced so as to face the entry / exit passage.

The power supply line 35 includes a second shut-off switch 38 in addition to the shut-off switch 31.
Is provided in the console box 30, and the second
Switch 38 is manually turned ON and OFF.
It is supposed to be. Further, the power supply line 35 is provided with an emergency cutoff switch 39. The emergency cutoff switch 39 is always ON, and in an emergency, the emergency excavator can be stopped urgently by turning the emergency cutoff switch 39 OFF.

With the above-described configuration, if either the shut-off switch 31 or the second shut-off switch 38 is in the OFF state, the shut-off valve 33 receives the pressure oil from the hydraulic pump 32. It is held at a position that is not supplied to an operation system (for example, an operation means including an operation lever and an operation pedal), and the lock lever 3
Reference numeral 6 is arranged at a position of an imaginary line that opens the passage for getting on and off. Therefore, the operator can get on and off without being disturbed by the lock lever 36. When the operator sits on the driver's seat and tilts the console box 30 to an operable state, the shut-off switch 31 is turned on. When the second shut-off switch 38 is manually turned on, the shut-off switch 38 is turned on. When the electromagnetic pilot portion 33a of the off valve 33 is energized, the shutoff valve 33 is switched,
The pressure oil from the hydraulic pump 32 can be supplied to the operation system. At the same time, the pressure oil is also supplied to the gate driving cylinder 37, and the gate driving cylinder 37 is operated, so that the lock lever 36 is displaced to the position indicated by the solid line that closes the passage for getting on and off. Therefore, in a state in which the hydraulic oil can be supplied from the hydraulic pump 32, the operator is unable to get off the cab because of the lock lever 36.

When the operator needs to get out of the cab during operation of the excavator, the console box 30 is tilted in the opposite direction to the above, and the shut-off switch 31 is turned off, or Is turned off. As a result, the shut-off valve 33 is closed, and the supply of the pressure oil from the hydraulic pump 32 is stopped. Therefore, even if the operator touches an operation lever, an operation pedal, or the like provided around the driver's seat, there is no danger that the operating parts of the hydraulic shovel will move unintentionally. At the same time, the pressure oil is not supplied to the gate driving cylinder 37, so that the lock lever 36 is displaced to the passage opening position. This secures the boarding passage,
The operator can get off the cab.

With the above configuration, the operator cannot get out of the operator cab unless the hydraulic actuators in the respective sections of the operation of the hydraulic shovel are not driven to stop. Further, since the lock lever 36 is automatically switched, there is an advantage that the operator can determine whether the hydraulic shovel is operable or inoperable by checking the position of the lock lever 36. .

[0017]

By the way, even when the operator is in the cab and the lock lever is in the closed state, the operating parts of the excavator must be kept stopped. is there. For example, at the excavation site, the operator may check the work state after the excavation has progressed to some extent, but for this purpose, it is necessary to look into the lower front part, and the operator must stand up from the driver's seat In some cases. At this time, although the operator has no intention to drive the hydraulic actuator, when the operator touches a part of the body such as the hand or foot of the operator, the operating mechanism of the hydraulic shovel moves. That is, even if the lock lever is provided,
Even if the operator has no intention to move the machine, it is impossible to prevent a situation in which the machine suddenly moves.

The present invention has been made in view of the above points, and a purpose thereof is to cause a situation in which the operating parts of the machine move even though the operator does not intend to move the machine. Is to ensure that it can be prevented.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention is directed to a cab of a construction machine, which faces an aisle where an operator gets on and off, and a position for blocking the aisle and opening the aisle. Provide a lock member that can be displaced to the position,
When the lock member is in the passage opening position, all the hydraulic actuators provided in the respective parts of the operation of the construction machine are disabled, and a load detecting means is provided in the driver's seat.
When a predetermined load does not act on the driver's seat, an operation stop means for disabling each of the hydraulic actuators is provided.

The load detecting means provided in the driver's seat detects the weight acting on the driver's seat when the operator sits down, and can be constituted by a switch which is turned on and off depending on the presence or absence of a load. For example, if the load is equal to or less than the set load, the switch is turned off, and if a load equal to or more than the set value is applied, the switch is turned on. Further, the lock member can be constituted by a lock lever which is manually rotated. Only when the lock lever is at the passage blocking position and the switch is turned on, the machine can be operated.

When the lock member is at the passage open position or when a predetermined load is not applied by the load detecting means, the construction machine is inoperable. This can be achieved by stopping the supply of pressure oil from the pump to each hydraulic actuator. The operation stopping means is for stopping the supply of pressure oil from the hydraulic pump to each hydraulic actuator. As the operation stopping means, for example, there is a means for opening and closing the flow path on the discharge side of the hydraulic pump. However, since a very high pressure acts on the flow path on the discharge side of the hydraulic pump that drives the hydraulic actuator, the configuration of the valve for shutting off the flow path becomes large. A directional control valve is interposed between the hydraulic pump and the hydraulic actuator. If the directional control valve is held at the neutral position, no pressure oil is supplied to the hydraulic actuator. Therefore, the means for forcibly holding all the directional control valves at the neutral position can be used as the operation stopping means. Switching of the directional control valve is performed by a pilot signal. The directional control valve is classified into an electromagnetically operated type and a hydraulic pilot type. In the case of the electromagnetically operated type, the supply of power to the electromagnetic pilot unit may be interrupted. In the hydraulic pilot system, a pilot pump is separately provided, and pressure oil is supplied from the pilot pump to a hydraulic pilot portion of each direction switching valve, and the switching is performed. Therefore, if the discharge flow path of the pilot pump is shut off, the direction switching valve is held at the neutral position and the hydraulic actuator does not operate even if the operating means is operated.
Since the discharge pressure from the pilot pump is not so high, it is possible to provide an electromagnetic switching valve in the pilot pump and open and close the discharge flow path by this electromagnetic switching valve. Therefore, a small electromagnetic switching valve can be used.
Further, as a hydraulic pump for supplying hydraulic oil to a hydraulic actuator, a variable displacement type hydraulic pump whose discharge flow rate changes in accordance with a load is generally used, and a pump regulator is provided to control the flow rate of this hydraulic pump. I have. Therefore, each hydraulic actuator can be kept in an inoperable state by setting the hydraulic pump to the minimum discharge flow rate state by the pump regulator.

There are various control target members for stopping the operation of the construction machine as described above, and any one of them may be controlled. The same member may be controlled by the lock lever and the load detecting means, or separate members may be controlled.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings, FIG. 1 is an overall configuration diagram of a lock device of a hydraulic shovel as a construction machine, FIG. 2 is an explanatory diagram of a configuration of a load detection unit, and FIG. 3 is another circuit configuration diagram of a lock mechanism.

First, in FIG. 1, reference numeral 50 denotes a driver's seat provided in a driver's cab, and reference numeral 51 denotes a position between a passage closing position facing a passage for getting on and off the operator for getting on and off the driver's cab and a passage opening position for opening the passage. Is a lock lever as a lock member that is displaced in the direction of the arrow. Reference numeral 52 denotes a pilot pump that supplies a hydraulic pilot signal to perform switching control of a directional switching valve that drives a hydraulic actuator. Reference numeral 53 denotes an electromagnetic switching valve that opens and closes a discharge-side flow path 54 of the pilot pump 52. The electromagnetic switching valve 53 constitutes an operation stopping means for forcibly stopping the operation of the hydraulic actuator irrespective of the state of the operating means.

The electromagnetic switching valve 53 is held at a switching position (a) for closing the flow passage 54 by a spring 53a, and is switched to the switching position (b) against the spring 53 when the electromagnetic pilot portion 53b is energized. Instead, the flow path 54 is opened. Therefore, by operating the operating means including the operating lever and the operating pedal provided around the driver's seat 50 with the electromagnetic switching valve 53 in the switching position (b), the hydraulic pilot signal is supplied to the direction switching valve. Thus, each hydraulic actuator can be driven. Electromagnetic pilot unit 53
b, a power supply 5 such as a battery
5 and two switches 57 and 58 are provided in the middle of a power supply line 56 from the power supply 55.
The switch 57 is turned ON and OFF by a lever 59 extended from a pivot 51a at the base end of the lock lever 51.
The switch 58 is connected to the driver's seat 5
It is turned ON and OFF according to a load of 0.

As shown by the solid line in FIG. 1, when the lock lever 51 is located in the passage closing position that prevents the operator from getting on and off the vehicle, the switch 5
When the switch 7 is turned ON, and is tilted about the pivot 51a to be displaced to the passage opening position where the passage for getting on and off is opened as shown by the solid line in FIG.
7 is in the OFF state. The lock lever 51 may be configured to be manually displaced, but may be hydraulically driven as shown in FIG.

The other switch 58 constitutes a load detecting means for the driver's seat 50. When the operator sits on the driver's seat 50, the switch 58 is turned on by detecting the load, and the operator turns on the driver's seat. Since the load disappears when the vehicle moves away from 50, the state is switched to the OFF state. It is provided in the driver's seat 50 and depends on the presence or absence of a load.
FIG. 2 shows an example of the switch 58 for turning off N and OFF.

As is clear from this figure, the seat 50a of the driver's seat 50 is not directly placed on the pedestal 50b, but has a link mechanism 59 interposed therebetween. The link mechanism 59 normally uses a spring 60 to control the seat 50.
a is held at a predetermined height from the pedestal 50b, and when the operator sits on the seat 50a,
The link mechanism 59 is deformed in a direction against the spring 60, and the seat 50a sinks by a predetermined amount. At this time, a pin 61 provided on one link plate 59a of the link mechanism 59 slides along an elongated hole 63 formed in an attachment portion 62 provided on the pedestal 50b side. Is placed on top. The switch 58 is connected to the seat 50a.
Is in a position away from the pin 61, the switch 58 is turned off.
When the operator sits down and the seat 50a sinks, the pin 61 slides along the long hole 63 and moves to the upper position of the switch 58. As a result, the switch 58 is pushed by the pin 61. Is turned on.

Generally, when operating means including operating levers provided on the left and right sides of the driver's seat 50 and operating pedals provided on the floor in front of the driver's seat 50, the hydraulic oil from the pilot pump 52 is used as a hydraulic pilot signal to switch the required direction. The pressure is supplied to the valve, the direction switching valve is switched, and the pressure oil from the hydraulic pump is supplied to the hydraulic actuator. This behavior is
The prior art is the same as that described with reference to FIG.

As described above, the hydraulic actuator is operated to operate various parts of the hydraulic excavator, ie, the operation of the front working mechanism, traveling, and turning of the upper revolving unit. When the is operated, the operating parts are not always operated, and will not operate unless certain conditions are satisfied. That is, only when the operator is seated on the driver's seat 50 and displaces the lock lever 59 to the passage closed state, the hydraulic actuator can be driven, assuming the intention to operate the hydraulic excavator. When the driver is not seated on the vehicle 50 or when the lock lever 59 is in the passage open state, there is no intention to operate the hydraulic shovel, and the operating parts are kept stationary.

For this purpose, an electromagnetic switching valve 53 is provided in the flow path on the discharge side of the pilot pump 52, and this electromagnetic switching valve 53 functions as an operation stopping means when conditions are not satisfied. The electromagnetic switching valve 53 always has a spring 53
It is held at the switching position (a) by the action of a. In this switching position (a), the hydraulic oil from the pilot pump 52 is shut off by the electromagnetic switching valve 53, and the pilot pressure signal is supplied to the hydraulic pilot portion of the direction switching valve even if the operating means moves. There is no. Therefore, no pressure oil is supplied to the hydraulic actuator.

There are two conditions under which the passage 54 is opened by the electromagnetic switching valve 53. First, the condition is that the operator gets into the cab and sets the lock lever 59 in the passage closed state. Then, the switch 57 is turned on. However, even if the operator enters the cab,
That alone does not switch the electromagnetic switching valve 53. Another condition is that the operator sits in the driver's seat 50. Whether or not the operator is seated on the driver's seat 50 can be detected based on whether or not a load acts on the seat 50a of the driver's seat 50. When a load acts on the seat 50a, the seat 50a sinks, and at this time, the switch 58 is turned on.

Only when the above two conditions are given, the electromagnetic pilot portion 53b of the electromagnetic switching valve 53 conducts with the power supply 55 and the electromagnetic pilot portion 53b is energized. B)
The flow path 54 on the discharge side of the pilot pump 52 is opened, so that a hydraulic pilot signal can be supplied to the hydraulic pilot section of the direction switching valve. As a result, when each operating means is operated, the direction switching valve provided for each is switched, and each hydraulic actuator is driven.

That is, the operation of the hydraulic excavator is as follows.
When the operator has an intention to operate the hydraulic shovel while sitting in the driver's seat 50 in the cab, the operable state is set. Even when the operator gets into the driver's cab and closes the lock lever 59 in the passage closed state, as long as the operator does not sit in the driver's seat 50, it is assumed that there is no intention to operate the hydraulic excavator. Also,
Hydraulic actuator is not driven. For example, when the operator is seated in the driver's seat 50 and performing operations such as excavation of earth and sand, the operation is stopped, and the operator stands up to confirm the excavated portion, the switch 58 is turned off.
In the state of F, the electromagnetic switching valve 53 switches to the switching position (A). As a result, even if the operating means is inadvertently touched by a part of the body such as a hand or a foot, the operating parts do not move unintentionally.

If the excavator can be operated when the operator is seated, it is sufficient to provide a switch 58 which is turned on and off in accordance with the load on the driver's seat 50, and is linked with the lock lever 59. Switch 57
Should not be necessary. However, for example, a situation may occur in which the operator places a heavy object such as luggage on the seat 50a of the driver's seat 50, or the operator may sit down on the driver's seat 50 and take a rest. Even when a load is acting on the seat 50, the operator does not always intend to operate the hydraulic shovel. When placing luggage or the like in the driver's seat 50, the lock lever 59 is displaced to open the passage, and
When resting at 0, the lock lever 59 is generally set to the passage open state. Therefore, based on the position of the lock lever 59 and the load on the driver's seat 50, the hydraulic shovel is set to an operable state in order to accurately determine whether the operator has an intention to operate the hydraulic shovel, Decide whether to make it inoperable. Thus, it is possible to reliably prevent a situation in which the operating parts of the hydraulic shovel move without permission even though the operator has no intention to operate.

Next, FIG. 3 shows another embodiment of the lock device. As is apparent from this figure, two electromagnetic on-off valves 70 and 71 are provided in the flow path 54 on the discharge side of the pilot pump 52, and these electromagnetic on-off valves 70 and 71 are provided.
Is normally kept closed by springs 70a, 71a, and electromagnetic pilot sections 70b, 7
When the power is supplied to 1b, the flow path 54 is opened. Then, the power supply line 56 from the power supply 55 is branched, and the electromagnetic pilot units 70a and 71a are respectively branched.
Connect to The branched power supply lines 56a and 56b are provided with a switch 57 that switches according to the position of the lock lever 51 and a switch 58 that switches according to the load on the driver's seat 50. In addition, the power supply lines 56a and 56b are provided with forced operation switches 72 and 73 that are turned on and off in parallel with the switches 57 and 58. The forced operation switches 72 and 73 are always kept in the OFF state,
It can be turned on manually by an operator.

With the above configuration, as described in the first embodiment, if the operator does not sit in the driver's seat 50 and the lock lever 51 does not close the passage, the hydraulic excavator can be used. Are kept stopped.

By the way, the switches 57 and 58 are both ON.
Otherwise, the excavator will not be in an operable state, and if one of the switches 57 or 58 is locked in the OFF state, the excavator cannot be moved. Therefore, when one of the switches 57 or 58 fails, the hydraulic shovel can be operated by manually turning on the forced operation switch 72 or 73 provided in parallel with the switch. Even if one of the switches 57 and 58 fails, the function as the lock device is exerted to some extent, and the state in which the hydraulic shovel becomes inoperable can be avoided.

[0039]

As described above, according to the present invention, when the lock member is located at the passage open position or the driver's seat is provided with load detecting means, and when the load detecting means does not detect a predetermined load, the construction machine The hydraulic actuator is actuated only when the operator sits in the driver's seat and displaces the lock lever to the passage closed state. When the operator is not seated in the driver's seat or the lock lever is in the passage open state, it is assumed that there is no intention to operate the excavator, and the operating parts are kept stationary and the lock is locked. The function of the device is improved.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view of a lock device of a construction machine showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of a load detection unit provided in a driver's seat.

FIG. 3 is a configuration explanatory view showing another embodiment relating to a lock device.

FIG. 4 is an external view of a hydraulic shovel as an example of a construction machine.

FIG. 5 is a hydraulic circuit diagram for driving each hydraulic actuator in the hydraulic shovel.

FIG. 6 is an explanatory diagram of a configuration of a cab.

FIG. 7 is an explanatory diagram of a configuration of a lock device according to a conventional technique.

[Explanation of symbols]

 50 Driver's seat 50a Seat 50b Pedestal 51 Lock lever 52 Pilot pump 53 Solenoid switching valve 54 Flow path 57,58 Switch 70,71 Solenoid on-off valve 72,73 Forced operation switch

Claims (5)

[Claims] An operator's cab of a construction machine is provided with a lock member which is displaceable between a position where the operator gets on and off the passage and a position where the passage is blocked and a position where the passage is opened. When the open position, when all the hydraulic actuators provided in each part of the operation of the construction machine is inoperable state, a load detecting means is provided in the driver's seat, when a predetermined load does not act on this driver's seat, A lock device for a construction machine, comprising: an operation stopping means for disabling each of the hydraulic actuators. 2. The lock device for a construction machine according to claim 1, wherein said load detecting means is constituted by a switch that operates when a predetermined load is applied. 3. The lock device for a construction machine according to claim 1, wherein said lock member comprises a lock lever. 4. A hydraulic pilot type directional switching valve which is switched by operating means provided in the cab is provided, and the driving of each of the hydraulic actuators is controlled by the directional switching valve. Is constituted by an electromagnetic switching valve that communicates and shuts off the flow path between the pilot pump and the hydraulic pilot portion of the direction switching valve, wherein the lock member is in the passage closed position and the load set in the driver's seat acts. 2. The lock device for a construction machine according to claim 1, wherein the pilot passage is opened by the solenoid-operated switching valve only when the load detecting means detects the operation. 5. An operation stopping means by the lock member,
2. The lock device for a construction machine according to claim 1, wherein the operation detecting means is different from the operation stopping means by the load detecting means, and each operation stopping means is provided with a forced operating means.