JP2588028Y2 - Safety device for hydraulic circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a hydraulic circuit.

[0002]

2. Description of the Related Art FIG. 5 is a side view schematically showing an example of a cab of a construction machine, and FIG. 6 is a conceptual diagram of a conventional hydraulic circuit related to a control valve shown in FIG.

A seat 1 shown in FIG. 5 is fixed on a floor 2 of a driver's cab via a seat mount 3. A valve mount 4 is provided on the floor 2 near the side of the seat 1. A control valve 5 for switching between forward and backward movement is fixed on the valve mount 4.

[0006] Reference numeral 6 denotes an operation lever of the control valve 5.

[0005] In front of the seat 1, a floor surface 2 of a driver's seat is provided.
A lever stand 7 for the attachment and the traveling body mounted thereon is provided.

Reference numeral 8 denotes an operation lever of the lever stand 7.

The control valve 5 has a pump port 9, a tank port 10, and pressure oil discharge ports 11 and 12, as shown in FIG.
And a switching valve body 14.

The operating lever unit 13 includes a support shaft 16 that extends through a substantially central portion of the internal space of the support block 15 in a horizontal direction, and the support block 15 is tilted in the forward A direction and the backward B direction by the support shaft 16. A cam 19 having a smooth lower surface, two notches 17 and 18 at upper and lower portions of a rear end surface, and having an operating lever 6 at an upper portion, and a rear portion of the support block 15. And a dedent device 20 provided toward the internal space.

The dident device 20 is formed so as to constantly urge the ball 22 forward A by a spring 21 provided therein. When the operation lever 6 is tilted forward A, the cam 19 is tilted together with the operation lever 6. Is engaged with the lower notch 18 of the cam 1 and the operation lever 6 is tilted rearward B side.
9 is engaged with the notch 17 on the upper side.

The switching valve body 14 is urged upward by a spring 23 so that the tip end thereof abuts against the lower surface of the cam 19 of the operation lever unit 13, and normally the tank port 10 and the pressure oil discharge ports 11 and 12. And two switching valves 25 and 26 having a spool 24 that communicates with the inside are arranged side by side in the front-rear direction.

When the operating lever 6 is tilted from the neutral position toward the front A side, the cam 1 that tilts with the operating lever 6 is moved.
9, the spool 24 of the switching valve 25 on the front A side is pushed down against the repulsive force of the spring 23, and the pump port 9 is connected to the pressure oil discharge port 11 via the switching valve 25.
When the operation lever 6 is tilted backward B, the cam 19 interlocking with the operation lever 6 pushes down the spool 24 of the switching valve 26 on the rear B side against the repulsive force of the spring 23, and the pump port 9 is the switching valve 26
Through the pressure oil discharge port 12.

Further, an electromagnetic switching valve 27 connected to the pump port 9 of the control valve 5 and a hydraulic pump 28 connected to the electromagnetic switching valve 27 are provided, and a solenoid 29 of the electromagnetic switching valve 27 is connected via a switch 30. When the solenoid 29 is excited by the power supply 31 via the switch 30 by the power supply 31, the electromagnetic switching valve 27 is set to a communication state, and the hydraulic pump 28 and the pump port 9 are formed to communicate with each other.

Reference numeral 32 denotes a relief valve provided between the hydraulic pump 28 and the electromagnetic switching valve 27.

In the construction machine having the above-described control valve, the hydraulic pump 28 is driven at the start of the operation, and the switch 30 is set to the conductive state.

When the switch 30 is turned on, the solenoid 29 of the electromagnetic switching valve 27 is excited, and the electromagnetic switching valve 27 is switched to the communicating state, so that the hydraulic pump 28 communicates with the pump port 9 and is discharged from the hydraulic pump 28. Pressure oil flows into the pump port 9.

When the operating lever 6 is tilted from the neutral position to the front A side, the cam 1 that tilts with the operating lever 6
9, the spool 24 of the switching valve 25 on the front A side is pushed down against the repulsive force of the spring 23, and the pump port 9 is connected to the pressure oil discharge port 11 via the switching valve 25.
When the operating lever 6 is tilted backward B, the cam 24 that is tilted together with the operating lever 6 pushes down the spool 24 of the switching valve 26 on the rear B side against the repulsive force of the spring 23, and the pump port 9 communicates with the pressure oil discharge port 12 via the switching valve 26, so that pressure oil is supplied from the hydraulic pump 28 to the main valve (not shown) via the control valve 5, and The spool is set to a forward position or a reverse position.

At this time, the operating lever 6 is engaged with the notches 17 and 18 of the cam 19 described above.
By 0, it is held in a state of being tilted to the forward position or the reverse position.

At the end of the operation, when the operation lever 6 is returned to the neutral position and the switch 30 is set to a non-conductive state,
The excitation of the solenoid 29 is released, the electromagnetic switching valve 27 is switched, and the hydraulic pump 28 and the pump port 9 are shut off.

[0019]

However, the operating lever 6 of the control valve 5 for switching between the forward and backward movements described above.
Is located in the vicinity of the side of the seat 1, so that even if the driver sets the operation lever 6 to the neutral position at the end of the work, the driver cannot get on and off the driver's seat of the construction machine. May touch the operation lever 6 to switch the operation lever 6 from the neutral position to the forward position or the reverse position. When the prime mover is operated without confirming the condition, the hydraulic power supply is turned on, the hydraulic pump 28 is driven, and when the switch 30 is turned on, the electromagnetic switching valve 27 is turned on.
When the driver operates the throttle lever, the construction machine may run in an unexpected direction because the solenoid 29 is excited and the hydraulic pump 28 communicates with the pump port 9.

The present invention has been made in view of the above circumstances, and provides a safety device for a hydraulic circuit in which an operation lever of a control valve in a neutral position is automatically fixed when a driver leaves a driver's seat. It was done for the purpose.

[0021]

According to a first aspect of the present invention, a driver seat is provided on a seat mount provided on a floor of a driver seat so as to be able to move up and down, and the seat is downward when the seat is seated and upward when the seat is released. And a limit switch is attached to one of the seat mount and the seat so that the limit switch becomes conductive at the time of sitting, and when the operation lever holds the neutral position. A control valve configured such that the pressure oil discharge port communicates with the tank port, and the pressure oil discharge port communicates with the pump port when the operation lever is tilted; A cylinder disposed so as to be able to be fitted into the recess provided in the cylinder, a resilient body for urging the piston of the cylinder toward the rod-side fluid chamber, and the pump port and the rod side of the cylinder. A pressure oil supply flow path for communicating the body chamber,
An electromagnetic switching valve provided between the pump port and the hydraulic pump, and the limit switch is disposed in an electric circuit connecting the electromagnetic switching valve and a power supply device. A step is provided below the front surface of the invented seat, which is integrated with the seat that projects horizontally.

[0022]

Therefore, in the safety device for a hydraulic circuit configured as described above, when the driver sits down on the driver's seat at the start of work, the seat is pushed down, the limit switch is turned on, and the electromagnetic switching valve is turned on. The switching is performed so that the hydraulic pump and the pump port communicate with each other. Next, when the hydraulic pump is driven, the pressure oil flows into the pump port via the electromagnetic switching valve, and flows into the rod-side fluid chamber of the cylinder through the pressure oil supply flow path. The pressure oil that has flowed into the rod-side fluid chamber moves the piston against the repulsive force of the resilient body, the tip of the piston rod is pulled out of the concave portion, and the restraint of the cam of the operating lever by the piston rod is released, The operation lever of the control valve can be tilted.

On the other hand, when the operation is completed, the operation lever is returned to the neutral position, and when the driver stands on the floor of the driver's seat and separates from the seat, the seat is raised, the limit switch is turned off, and the electromagnetic switching is performed. The valve is switched to shut off the hydraulic pump and the pump port, so that the hydraulic oil discharged from the hydraulic pump does not flow into the rod-side fluid chamber of the cylinder.

When the pressure oil no longer flows into the rod-side fluid chamber, the piston is pushed out by the repulsive force of the resilient body in the cylinder, and the tip end of the piston rod fits into the concave portion of the operating lever base, and the piston rod operates. The lever is restrained and fixed in a neutral state.

According to the second invention, when the driver stands on the floor of the driver's seat and stands up by stepping, the seat does not rise even when the driver leaves the seat, so that the conduction state of the limit switch is maintained. The operation lever of the control valve can be tilted.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual view of an embodiment of a safety device for a hydraulic circuit according to the present invention, FIG. 2 is a side view schematically showing an example of a cab related to FIG. 1, and FIG. 3 is a seat related to FIG. FIG. 4 is a side view schematically showing another example of the driver's cab related to FIG. 1, and the same reference numerals in FIG. 4 denote the same parts as in FIGS. 5 and 6. The description will be omitted by attaching.

In the embodiment of the first invention, as shown in FIG. 2, a seat mount 33 is provided at a predetermined position on the floor 2 of the driver's seat, and predetermined lengths are provided at four corners on both sides of the seat mount 33. The support lever 34 is disposed so as to be tiltable in the front-rear direction of the seat mounting table 33, and the seat 1 is attached to the tip end of the support lever 34. A spring 35 is formed between the seat mount 33 and the seat 1 so as to move in parallel and urge the seat 1 upward. When the driver sits on the seat 1, the seat 1 is lowered to a predetermined low height. The seat 1 is formed so as to be able to automatically return to a predetermined height position by the repulsive force of the spring 35 when the driver stops from the seat 1 and moves down to the seat position.

A limit switch 37 having a lever 36 that rotates in a plane parallel to the moving direction of the seat 1 is attached to a lower side surface of the seat 1, and a limit switch 37 that descends with the seat 1 is brought into contact with a tip of the lever 36. A striker 3 which can contact and tilt the lever 36 by a predetermined angle.
8 is disposed on the side surface of the seat mount 33.

Further, a valve mount 4 is provided on the floor 2 near the side of the seat 1, and a control valve 39 for switching between forward and backward is fixed on the valve mount 4.

Reference numeral 6 denotes an operation lever of the control valve 39.

The control valve 3 of the present embodiment
As shown in FIG. 1, in the operation lever unit 40 constituting the operation lever 9, a hole which is substantially horizontal when the operation lever 6 is located in the neutral state is formed in the center of the front end face of the cam 19 of the operation lever 6. 41 is provided, and a hole 42 is provided on the side of the front A side of the support block 15 corresponding to the hole 41 so as to pass substantially horizontally from the front of the support block 15 toward the internal space.
, A cylinder 45 having a piston rod 44 which is extended by being urged by a spring 43 is inserted therethrough, and the front end of the piston rod 44 is fixed so that it can be fitted into a hole 41 provided on a front end surface of the cam 19 portion. The pressure oil supply passage 4 is connected to the rod side fluid chamber 46 of the cylinder 45 and the pump port 9.
When the pressure oil flows into the rod side fluid chamber 46 from the pump port 9 via the pressure oil supply flow path 47,
The pressure oil resists the repulsive force of the spring 43 and the piston 48
Is moved to the front A side to shorten the protruding length of the piston rod 44.

Further, in the hydraulic circuit of the present embodiment, as shown in FIG. 1, the above-described limit switch 37 is connected to an electric circuit between the power supply device 31 of the hydraulic circuit and the electromagnetic switching valve 27. .

Other than the above, there is no difference in basic structure from the conventional example shown in FIG.

Next, the operation of this embodiment will be described.

At the start of the work, when the driver sits down on the driver's seat 1, the seat 1 is pushed down against the repulsive force of the spring 35 along the turning trajectory of the tip of the support lever 34,
Stop at a predetermined low position.

When the seat 1 is lowered to the low position, and the lever 36 of the limit switch 37 contacts the striker 38 and turns, the limit switch 37 is set to the conductive state.

When the limit switch 37 is turned on, the solenoid 29 of the electromagnetic switching valve 27 is excited, and the electromagnetic switching valve 27 is switched to the communicating state, so that the hydraulic pump 28 and the pump port 9 communicate with each other.

Then, when the hydraulic pump 28 is driven, the pressure oil flows into the pump port 9 via the electromagnetic switching valve 27 and flows into the rod side fluid chamber 46 of the cylinder 45 through the pressure oil supply flow path 47.

The pressure oil flowing into the rod-side fluid chamber 46 moves the piston 48 toward the front A side against the repulsive force of the spring 43, so that the protruding length of the piston rod 44 is reduced, and the tip of the piston rod 44 Since the portion is pulled out from the hole 41 of the cam 19 of the operation lever 6, the restriction of the cam 19 of the operation lever 6 by the piston rod 44 is released, so that the operation lever 6 of the control valve 5 can be tilted. become.

On the other hand, at the end of the operation, the operation lever 6
Is returned to the neutral position, and when the driver stands on the floor 2 of the driver's seat and separates from the seat 1, the seat 1 is urged by the repulsive force of the spring 35 and rises along the rotation locus of the tip of the support lever 34. Then, it stops at a predetermined high position.

When the seat 1 rises, the limit switch 3
Since the lever 36 rotates away from the striker 38, the limit switch 37 is set to a non-conductive state.

When the limit switch 37 is set to the non-conductive position, the solenoid 29 of the electromagnetic switching valve 27 is de-energized, the electromagnetic switching valve 27 is switched, and the hydraulic pump 28 and the pump port 9 are cut off. Valve 2
7, the pressure oil discharged from the hydraulic pump 28 does not flow into the rod-side fluid chamber 46 of the cylinder 45, and the pressure oil remaining in the rod-side fluid chamber 46 is Flows back to the tank via the electromagnetic switching valve 27.

The piston 48 in the cylinder 45 from which the hydraulic pressure in the rod-side fluid chamber 46 has been removed is moved rearward by the repulsive force of the spring 43, so that the piston rod 4
4, the distal end of the piston rod 44 is fitted into the hole 41 of the cam 19 at the base of the operating lever 6 located in the neutral state, and the cam 19 of the operating lever 6 is restrained by the piston rod 44. The operation lever 6 of the control valve 5 is fixed in a neutral state.

In this embodiment, since the operation lever 6 of the control valve 5 can be automatically fixed to the neutral position at the end of the work, when this device is applied to a construction machine, etc. When getting on or off a machine or the like, the driver's legs touch the operation lever 6 and the operation lever 6
Does not switch from the neutral position to the forward position or the reverse position.

Therefore, when the operation is started next time, the operation lever 6 of the control valve 5 is maintained at the neutral position, and the construction machine or the like does not run in an unexpected direction.

Further, a limit switch 37 connected between the electromagnetic switching valve 27 and the power supply device 31 is incorporated in the seat 1. When the limit switch 37 is turned on by the driver's seat, and when the driver leaves the seat 1, the limit switch 37 becomes non-conductive. Since it is formed so as to be in a conductive state, it is not necessary to shut off the power supply of the safety device of the hydraulic circuit at the end of the work.

Next, an embodiment of the second invention will be described.

The safety device for the hydraulic circuit of this embodiment is the same as that of the first embodiment shown in FIG. 1, and there is no change at all.

The basic structure of the cab is substantially the same as that of the cab of the first invention shown in FIGS.

In the second invention, as shown in FIG. 4, a base fixed to each of the left and right sides of the seat 1 is provided, and a side surface is provided so as to hang down from the tips of both bases and project horizontally below the front of the seat 1. Except that a step 49 is formed below the front surface of the seat 1 except that the step 49 is formed into an L-shape and extends horizontally toward the center of the seat 1 in the width direction, and is formed by both end portions connected to each other at the center of the seat 1 in the width direction. Since it is the same as the embodiment of the first invention shown in FIGS. 1, 2 and 3, the following description is omitted.

Next, the operation of the present embodiment will be described. When the driver sits down on the driver's seat 1 at the start of the work or steps down at step 49, the seat 1 moves along the rotation locus of the tip of the support lever 34. The spring 35 is pushed down against the repulsive force and stops at a predetermined lower position.

The following operation is the same as that of the first embodiment shown in FIGS. 1, 2 and 3, but in the case of the embodiment shown in FIG. 37 can be set to the conductive state, so that the driver can stand on the floor 2 of the driver's seat as required, and thus can take a more free driving posture than in the embodiment shown in FIG.

The present invention is not limited to the above-described embodiment. For example, a limit switch may be attached to the seat mount, application to devices other than construction machinery, It goes without saying that various changes can be made without departing from the spirit of the invention.

[0055]

[Effect of the invention] According to the safety device for the hydraulic circuit of the invention,
Various excellent effects can be obtained as described below.

I) Since the operation lever of the control valve can be automatically fixed to the neutral position at the end of the work, the driver's leg or the like touches the operation lever, and the operation lever switches from the neutral position. There is no end.

II) Next, when the operation is started, the operation lever of the control valve is maintained at the neutral position, and no malfunction occurs.

[Brief description of the drawings]

FIG. 1 is a conceptual view of an embodiment of a safety device for a hydraulic circuit according to the present invention.

FIG. 2 is a side view schematically showing an example of a cab related to FIG.

FIG. 3 is a side view showing a case where the seat related to FIG. 2 is in a low position.

FIG. 4 is a side view schematically showing another example of the cab related to FIG. 1;

FIG. 5 is a side view schematically illustrating an example of a cab of the construction machine.

FIG. 6 is a conceptual diagram of a conventional hydraulic circuit related to the control valve of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Seat 2 Floor 6 Operation lever 9 Pump port 10 Tank port 11 Pressure oil discharge port 12 Pressure oil discharge port 27 Electromagnetic switching valve 28 Hydraulic pump 31 Power supply 33 Seat mount 36 Lever 37 Limit switch 39 Control valve 41 Hole (recess) ) 43 Spring (elastic body) 44 Piston rod 45 Cylinder 46 Rod side fluid chamber 47 Pressure oil supply flow path 48 Piston 49 Step

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F15B 20/00 E02F 9/24

Claims (2)

(57) [Scope of request for utility model registration] A driver seat is provided on a seat mount provided on a floor surface of the driver seat so as to be able to move up and down, and the seat is configured to move downward when sitting down and upward when leaving the seat. A limit switch is attached to one of the mounting base and the seat so that the limit switch becomes conductive when seated, and the pressure oil discharge port communicates with the tank port when the operation lever is in the neutral position. Also, a control valve configured so that the pressure oil discharge port communicates with a pump port when the operation lever is tilted, and a tip end portion of a piston rod can be fitted into a concave portion provided in the operation lever base. An arranged cylinder, a resilient body for urging a piston of the cylinder toward the rod-side fluid chamber, and a pressure oil supply passage communicating the pump port with the rod-side fluid chamber of the cylinder. An electromagnetic switching valve provided between the pump port and the hydraulic pump, and the limit switch disposed in an electric circuit connecting the electromagnetic switching valve and a power supply device. . 2. The seat according to claim 1, wherein a step of projecting horizontally below the front surface of the seat is provided integrally with the seat.
Hydraulic circuit safety device as described.