JPH0117505Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a cab tailing device using hydraulic pressure.

<Background Art> A cab tilt device using a hydraulic cylinder is configured as shown in FIG. 1, for example. That is, the cab 2 hinged to the tip of the vehicle frame 1 is tilted around the hinge by a hydraulic cylinder 3. The hydraulic cylinder 3 has its cylinder body side connected to the vehicle frame 1, and its rod side connected to the cab 2. They are connected to each other so that they can rotate freely. Then, hydraulic oil is selectively supplied to the head side chamber or rod side chamber of the hydraulic cylinder 3, and the cab 2
It's starting to tail. A locking device 4 locks the cab 2 to the vehicle frame 1.

By the way, in a cab tailing device using such a hydraulic cylinder, the rod position of the hydraulic cylinder 3 is detected and the operation of the oil supply pump is automatically activated so that the cab automatically stops at the tipping position or the running position when the cab tailing is operated. It is configured to stop at.

However, such a conventional stopper mechanism uses two limit switches to detect the extended position and the retracted position of the rod using separate limit switches. For this reason, two switches for position detection are required, which is uneconomical, and the switch must be installed near the hydraulic cylinder because it is necessary to detect the extended and contracted positions of the rod. A cover, etc. was necessary because it easily got dirty. This type of stopper mechanism is disclosed in Japanese Unexamined Patent Publication No. 57-155168 and Japanese Utility Model Application No. 58-58982.

<Purpose of the invention> This invention was made in view of the above circumstances.
We have solved the conventional problems by having a configuration that detects the rod position based on the hydraulic condition rather than the extended and retracted positions of the rod of the hydraulic cylinder, and by creating a configuration that allows the rod position to be detected with low operating oil pressure. purpose.

<Summary of the invention> For this reason, in the present invention, in a cab tailing device that uses a hydraulic cylinder to tilt a cab, the hydraulic cylinder is connected to an oil supply path for supplying hydraulic oil from an oil supply pump to the cab tailing hydraulic cylinder. A passage switching valve for selectively supplying hydraulic oil to the head chamber side and the rod chamber side is installed, and an oil relief passage is connected to the oil supply passage between the oil supply pump and the passage switching valve, and the oil relief passage A first relief valve that opens when the oil pressure in the oil supply path exceeds a predetermined value, and a second relief valve located downstream of the first relief valve and having a hydraulic pressure relief port are interposed, and By providing a hydraulic pressure detection means that outputs a signal to stop the operation of the oil supply pump when it detects that a hydraulic pressure of more than a predetermined value has been generated in the oil relief passage between the two relief valves, the cab can be moved to the tilt position or when the cab is tilted. It is configured to automatically stop at the running position.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Incidentally, the same elements as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

FIG. 2 shows a hydraulic circuit of a first embodiment of the cab tail device according to the present invention. In the figure, 11
is an oil supply pump driven by a motor 12. The suction side of the oil supply pump 11 communicates with an oil reservoir 16 through an oil supply passage 15 having a check valve 13 and an oil strainer 14 interposed therebetween. Further, the discharge side is connected to the head side chamber 3A and rod side chamber 3B of the cab tail hydraulic cylinder 3 via a passage switching valve 18 interposed in the oil supply path 17 so as to be able to communicate with each other.
Each oil supply path 17A, 17B connecting the switching valve 18 and the head side chamber 3A or the rod side chamber 3B has a check valve 19 having a pilot valve, respectively.
A, 19B and oil filters 20A, 20B are interposed. 21 is a check valve installed in the oil supply passage 17, and 22 is an oil return passage connecting the switching valve 18 and the oil reservoir 16.

Furthermore, the passage switching valve 18 and the check valve 2 of the oil supply passage 17
1, the first relief valve 2 opens to the oil reservoir 16 and opens when the oil pressure in the oil supply path 17 exceeds a predetermined value.
3, and connect the oil relief passage 24 with oil supply passage 1
Relief valve 2 is activated when the oil pressure in 7 exceeds a predetermined value.
3 is opened to prevent an abnormal pressure rise in the oil supply passage 17. In this embodiment, the oil relief passage 24 is provided with a second relief valve 35 having a hydraulic pressure relief port on the downstream side of the first relief valve 23, and the oil pressure between the two relief valves 23 and 35 is detected. A hydraulic switch 25 is provided as hydraulic pressure detection means. The oil pressure switch 25 is normally on, and is configured to turn off when a hydraulic pressure higher than a set value is detected, and is connected in series between the battery 26 and the oil supply pump drive motor 12. Reference numeral 27 denotes an automatic return type push button type motor operating switch connected in series between the hydraulic switch 25 and the motor 12. In addition, in the figure,
28 is a manual pump for use when the oil supply pump 11 is not operating, 29 and 30 are check valves, and 31 is an air vent valve.

Next, the effect will be explained.

Here, the flow state of hydraulic oil during cab tail operation in this hydraulic circuit will be briefly described.

First, when tilting the cab 2, the passage switching valve 18 is set to the right position as shown in the second figure.
Next, when the operating switch 27 is pressed to turn on, the motor 12 is turned on because the hydraulic switch 25 is in the on state.
The oil supply pump 11 is started by the motor 12 connected to the battery 26 . Then, hydraulic oil is sucked from the oil reservoir 16 through the oil supply path 15 and is transferred from the oil supply path 17 on the discharge side to the oil supply path 17 via the switching valve 18.
Hydraulic oil is supplied from A to the head side chamber 3A of the hydraulic cylinder 3 through the filter 20A and the check valve 19A, the rod 3C is extended and the cab 2 is raised. At this time, the hydraulic oil in the rod side chamber 3B is transferred to the oil supply path 17A.
The oil flows out through the pilot valve of the check valve 19B opened by the oil pressure, and is returned to the oil reservoir 16 from the oil return passage 22 via the oil supply passage 17B, the filter 20B and the switching valve 18.

On the other hand, when lowering the cab 2, the passage switching valve 18 is switched to the left position, contrary to the above.
As a result, the hydraulic oil discharged from the oil supply pump 11 passes through the switching valve 18 and is then supplied from the oil supply path 17B to the rod side chamber 3B of the hydraulic cylinder 3 via the filter 20B and the check valve 19B, causing the rod 3C to contract and the cab 2 to open. Descend. And head side room 3A
The hydraulic oil on the side is turned off by the check valve 1 as the rod 3C moves.
It flows out through the pilot valve 9A and enters the oil supply line 17.
From A, the oil is returned to the oil reservoir 16 via the switching valve 18 and the oil return passage 22. Note that the operating switch 27 is kept pressed while the cab is tilting.

In such a hydraulic circuit, when the rod 3C of the hydraulic cylinder 3 becomes fully extended or compressed due to cab tail operation, a condition called bottoming out occurs in the hydraulic cylinder 3, and the oil pressure on the discharge side of the oil supply pump 11 decreases. It will rise higher than when Rod 3C was on the move. When the oil pressure exceeds a predetermined value, the first relief valve 23 of the oil relief passage 24 opens, and oil pressure is generated on the downstream side thereof. This generation of oil pressure turns off the oil pressure switch 25. Therefore, the power to the motor 12 is cut off, the motor 12 is stopped, the oil supply pump 11 stops supplying oil to the hydraulic cylinder 3, and the raising or lowering operation of the cab 2 is automatically stopped.

In this way, if the hydraulic pressure in the oil supply path 17 is sensed to detect the elevation position of the cab 2, only one detection switch is required, reducing costs, and the detection switch can be installed near the hydraulic cylinder 3. This increases the degree of freedom in layout, and allows installation in locations that are difficult to get dirty, improving reliability and durability.

Further, in this case, since the operating oil pressure value of the oil pressure switch 25 can be lowered, a low pressure sensing type switch can be used, the cost of the oil pressure switch can be reduced, and the reliability can be further improved. Note that the hydraulic pressure between the relief valves 23 and 35 is such that the hydraulic oil flows into the oil sump 16 through the oil relief port of the relief valve 35 on the downstream side.
As a result, the hydraulic pressure gradually decreases and the hydraulic switch 25 is turned on by the time of the next cab tail operation.

<Effects of the invention> As described above, according to the invention, the configuration is such that the oil pressure increases as the hydraulic cylinder bottoms out to detect the cab stop position when the cab is tilted using an oil pressure sensing switch, etc. Only one detecting means is required, and the position detecting means can be mounted at a location other than the vicinity of the hydraulic cylinder where it is easily contaminated. Therefore, layout constraints are relaxed, design freedom is improved, and it is possible to prevent dirt from being soiled even without a cover, improving reliability and economical efficiency. Further, since the operating oil pressure value of the oil pressure sensing type switch can be lowered, a low pressure sensing type switch can be used, so that the cost of the oil pressure sensing type switch can be reduced and the reliability can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a cab tail device using a hydraulic cylinder, and FIG. 2 is a hydraulic circuit diagram showing one embodiment of the cab tail device according to the present invention. 2... Cab, 3... Hydraulic cylinder, 3A...
Head side chamber, 3B... Rod side chamber, 3C... Rod, 11... Oil supply pump, 12... Motor, 17
... Oil supply passage, 18 ... Passage switching valve, 25 ... Oil pressure switch, 26 ... Battery, 27 ... Operation switch, 23 ... First relief valve, 35 ... Second relief valve.

Claims (1)

[Scope of utility model registration request] In a cab tailing device in which a cab that is directly or indirectly hinged to a vehicle frame is tilted around the hinge by a hydraulic cylinder, the hydraulic cylinder is connected to an oil supply path for supplying hydraulic oil from a fuel pump to the cab tail hydraulic cylinder. A passage switching valve is installed to selectively supply hydraulic oil to the head chamber side and the rod chamber side, and
An oil relief passage is connected to the oil supply passage between the oil supply pump and the passage switching valve, and the oil relief passage includes a first relief valve that opens when the oil pressure in the oil supply passage exceeds a predetermined value; A second relief valve located downstream of the first relief valve and having an oil relief port is interposed, and when it is detected that a hydraulic pressure of a predetermined value or more is generated in the hydraulic pressure relief passage between the two relief valves, the oil supply is performed. A cab tailing device characterized by being provided with a hydraulic pressure detection means for outputting a pump operation stop signal.