JP2007309378A - Cab tilting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase pushing-up thrust while securing a lost motion region of a cab tilting device. <P>SOLUTION: A tilting cylinder device 3 has an upside oil path 11 laid between a cab 1 and a frame 2 for supplying/draining pressure oil to an upside hydraulic pressure chamber 5a of the tilting cylinder device 3 which tilts the cab, and a downside oil path 12 for supplying/draining the pressure oil to a downside hydraulic pressure chamber 5b. A communication pipe 74 is provided for communicating the upside hydraulic pressure chamber 5a with the downside hydraulic pressure chamber 5b, and a poppet valve 70 is provided in the communication pipe 74 for shutting off the passage of the communication pipe 74 during elongation. Lost motion during travel is secured with the pressure oil coming in or going out of the communication pipe 74. The flow of the pressure oil supplied to the upside hydraulic pressure chamber 5a into the downside hydraulic pressure chamber 5b through the passage of the communication pipe 74 during elongation is prevented by the poppet valve 70. Thus, a double-acting cylinder is used instead of a differential cylinder for operation to improve thrust during elongation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cabylt device mounted on a cab over engine type automobile.

  For medium and large cab-over type trucks, cabbutylt equipment is used. The cabylt device is equipped with a tilt cylinder device between the cab and the frame, and the cab is lifted and lowered by the expansion and contraction of the tilt cylinder device to facilitate maintenance and inspection work around the engine and the engine. It is made to be able to.

  As a conventional cabylt device of this type, an air spring or a coil spring is interposed between the cab and the frame as a means for isolating the cab from the vibration and swaying of the running frame, and the frame of the tilt cylinder device There is a type provided with a tilt device having a communication pipe that connects a side hydraulic chamber (push chamber) and a cab side hydraulic chamber (pull chamber) to each other in a limited portion. For example, see Patent Document 1.

Japanese Patent Publication No.53-478

In general, a cabylt device having a communication pipe that allows a frame side hydraulic chamber and a cab side hydraulic chamber to communicate with each other supplies pressure oil simultaneously to the cab side hydraulic chamber and the frame side hydraulic chamber during cylinder extension operation, A differential cylinder is employed in which the piston is moved by the difference between the force generated in the piston by the pressure oil and the force generated in the piston by the pressure oil in the frame side hydraulic chamber.
Such a differential cylinder device is a simple and good method for adding a lost motion function to the cylinder device.
However, on the other hand, there is a problem that the pushing-up thrust is smaller than that of a double-acting cylinder device having the same diameter, and the cylinder device becomes large in order to lift the same cab.

  Therefore, as an improvement plan for the problems of the differential cylinder device, when the cylinder is extended, pressure oil is supplied to the frame side hydraulic chamber, the pressure oil is discharged from the cab side hydraulic chamber, and when the cylinder is shortened, the cab side hydraulic pressure is discharged. A return cylinder that supplies pressure oil to the chamber and discharges the pressure oil from the frame-side hydraulic chamber is adopted, and a communication pipe that connects the frame-side hydraulic chamber and the cab-side hydraulic chamber is provided, and the cylinder is extended. Some proposals have been made to cut off this communication pipe. For example, see Patent Document 2.

Japanese Patent Publication No. 3-71310

However, in the above-described cabylt device, since the communication pipe is blocked at the outer diameter portion of the pilot piston, a gap for reciprocating the pilot piston is required in the blocking portion of the communication pipe. Therefore, oil leaks from this portion to the cab side hydraulic chamber and the pump side.
On the other hand, a hydraulic pump for carbitol generally has a characteristic that a discharge amount per one rotation is small and a discharge pressure is high.
Therefore, even if a small amount of oil leaks in the hydraulic circuit, the extension speed of the carbylate cylinder is greatly affected and slows down, which causes a problem that the cabbutylt up takes time and the vehicle cannot be inspected efficiently. There is.

  An object of the present invention is to provide an efficient carbylating apparatus with less oil leakage in a cylinder having a hydraulic lost motion function.

Typical means for solving the above-described problems are as follows.
(1) a tilt cylinder device that is interposed between the cab and the frame and tilts the cab;
A raising-side supply / discharge oil passage for supplying or discharging pressure oil to / from the frame-side hydraulic chamber of the tilt cylinder device;
A lower-side supply / discharge oil passage for supplying or discharging pressure oil to the cab-side hydraulic chamber of the tilt cylinder device;
A pilot check valve interposed in each of the up-side supply / discharge oil passage and the down-side supply / discharge oil passage; a communication passage for communicating the frame-side hydraulic chamber and the cab-side hydraulic chamber with each other;
A poppet valve that blocks the communication path when the tilt cylinder device is extended and prevents the pressure oil supplied to the frame-side hydraulic chamber from flowing into the cab-side hydraulic chamber through the communication path;
A cabylt device characterized by comprising:
(2) A valve unit is provided at or near the end of the tilt cylinder device. The valve unit includes a pilot check valve interposed in the raising side oil supply / discharge passage, and the lowering unit. The pilot check valve interposed in the side oil supply / discharge passage and the poppet valve interposed in the communication path between the frame side hydraulic chamber and the cab side hydraulic chamber are integrally formed. The carbitol device according to (1), characterized in that it is characterized in that
(3) During the extension operation of the tilt cylinder device, the valve opening pressure of the pilot check valve interposed in the lower-side supply / discharge oil passage is between the frame-side hydraulic chamber and the cab-side hydraulic chamber. The carbylator device according to (1) or (2), wherein the poppet valve interposed in the communication path is set so as to open only after the communication path is blocked.
(4) The cabylt device according to (1), (2), or (3), wherein the poppet valve is configured as a two-port, two-position / pilot switching valve.
(5) The pilot switch device according to (4), wherein the pilot switching operation portion of the poppet valve includes a small diameter cylinder chamber and a large diameter cylinder chamber.

According to the above (1), the poppet valve is provided in the communication path, and unlike the above-mentioned Patent Document 2, there is no gap in the communication path blocking portion. Therefore, the poppet valve is connected by the poppet valve when the tilt cylinder device is extended. It is possible to block the passage reliably and prevent the pressure oil supplied to the frame side hydraulic chamber from flowing into the cab side hydraulic chamber through the communication passage. The cylinder can be efficiently extended in a short time.
According to the above (2), since the poppet valve forms the valve unit together with the pilot check valve of the raising side supply / discharge oil passage and the lower side supply / discharge oil passage, there is no need to pipe around the cylinder device. Therefore, the cost can be reduced.
According to the above (3), the check valve of the lower-side supply / discharge oil passage is opened after the communication path between the frame-side hydraulic chamber and the cab-side hydraulic chamber is reliably shut off by the poppet valve. Even if the amount or the viscosity of the hydraulic oil changes, the pressure oil in the frame side hydraulic chamber can be prevented from flowing out to the cab side hydraulic chamber or the pump side, and tilting can be reliably performed.
According to said (4), a valve unit can be made compact by making the said poppet valve the simple structure of 2 ports, 2 positions, and a pilot switching valve.
According to the above (5), since the small diameter cylinder chamber and the large diameter cylinder chamber are provided in the pilot switching operation portion of the poppet valve, the poppet valve can be moved differentially.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the cabylt device according to the present embodiment includes a tilt cylinder device 3 that is interposed between a cab 1 and a frame 2 and performs a tilt operation of the cab 1 by hydraulic expansion and contraction. ing.
That is, the cab 1 is supported by the frame 2 so as to be rotatable in the front-rear direction by a fulcrum 1 a, and the upper end of the piston rod 4 of the tilt cylinder device 3 is pivotally attached to the cab 1. Is pivotally attached to the frame 2.
As shown in FIG. 2, a cab lock device 6 is installed at the center of the rear end of the cab 1. The cab lock device 6 is a device that connects the cab 1 and the frame 2 and releases the connection.
That is, at the rear end of the cab 1, the left and right frames are connected by a mountain-shaped rear arch 6a, and a floating bar 6c is attached to the rear arch 6a via a coil spring or an air spring 6b. The cab lock device 6 is a device that connects the cab 1 to the floating bar 6c and releases the connection when the cab is tilted.

As shown in FIG. 3, the hydraulic drive circuit 10 of the tilt cylinder device 3 includes a raising-side supply / discharge oil passage (hereinafter referred to as a raising-side oil passage) 11 and a lower-side supply / discharge oil passage (hereinafter referred to as a lowering). Side oil passage) 12, a pump 13 driven by a motor M, a tank 14, and a manual switching valve (hereinafter referred to as a switching valve) 15.
The raising side oil passage 11 is fluidly connected to a frame side hydraulic chamber (hereinafter referred to as raising side hydraulic chamber) 5 a of the cylinder 5, and the lowering side oil passage 12 is connected to the cab side hydraulic chamber (hereinafter referred to as lowering portion) of the cylinder 5. Side hydraulic chamber) fluidly connected to 5b.

The switching valve 15 is constituted by a 4-port, 2-position, manually operated switching valve, and the switching lever 15a supplies the pressure oil from the pump 13 to the upside supply / discharge oil passage 11 or the downside supply / discharge oil. Whether to supply to the path 12 is switched.
When the switching valve 15 is normal vehicle traveling in Ya stopping cars and parking secondary, as shown in FIGS. 5 and 7, is set at a position of the cab tilt-down. That is, the load port a of the raising side oil passage 11 is connected to the tank port T, and the load port b of the lowering side oil passage 12 is connected to the pump port P.
When the cab is switched to the tilt-up position to tilt up the cab, as shown in FIG. 3, the load port a of the raising side oil passage 11 is connected to the pump port P and the load of the lowering side oil passage 12 is loaded. Port b is connected to tank port T, respectively.

The raising side oil passage 11 is provided with a pilot operation type check valve (hereinafter referred to as a raising side pilot check valve) 16 for the raising side oil passage, and the lower side oil passage 12 is for the lower side oil passage. A pilot-operated check valve (hereinafter referred to as a lower-side pilot check valve) 17 is interposed.
The raising side pilot check valve 16 prevents the flow from the cylinder 5 side to the switching valve 15 side when the pressure of the lowering side oil passage 12 is less than a preset pilot pressure value. It is designed to allow flow.
The lower side pilot check valve 17 prevents the flow from the cylinder 5 side to the switching valve 15 side when the pressure in the raising side oil passage 11 is less than a preset pilot pressure value, and when the pressure exceeds the set value. , To allow that flow.
In a specific embodiment, the raising side pilot check valve 16 is set to open at a low pressure of 0.6 MPa, and the lowering side pilot check valve 17 is set to open at a higher pressure of 2.4 MPa. Yes.
This is because the poppet valve 70 generates a hydraulic pressure in the pilot passage 85 of the poppet valve 70 that reliably shuts off the communication path between the raising side hydraulic chamber 5a and the lowering side hydraulic chamber 5b.
In the hydraulic circuit shown in FIG. 3, the raising side oil passage 11 and the pilot passage 85 are depicted as separate circuits. However, in the specific example shown in FIG. 11 and the pilot passage 85 overlap.

  In FIG. 3, 7 is a check valve installed in the pump 13, 8 is a filter installed in the tank 14, and 9 and 9A are relief valves.

As shown in FIG. 9, a valve unit 20 is installed at the frame side end of the cylinder 5 of the tilt cylinder device 3.
As shown in FIG. 4, FIG. 6, and FIG. 8, the valve unit 20 is formed with an upside pilot check valve 16 and a downside pilot check valve 17.
4, 6, and 8 have the same shape, but FIG. 4 shows the valve position and oil flow direction when the cab is tilted up, and FIG. 6 tilts the cab. FIG. 8 shows the position of the valve and the flow of oil when the carbylating device is in a lost motion state.
As shown in FIG. 4, on the lower end surface of the body 21 of the valve unit 20, the switching valve side port (hereinafter referred to as the first port) 22 of the raising side oil passage 11 and the switching of the lower side oil passage 12 are provided. Valve side ports (hereinafter referred to as second ports) 23 are arranged side by side in the horizontal direction (hereinafter referred to as the left and right direction).
A pipe nipple (not shown) that forms the raised oil passage 11 is screwed into the female thread portion 24 of the first port 22, and the lower oil passage 12 is connected to the female screw portion 25 of the second port 23. A nipple (not shown) of the duct to be formed is screwed. Filters 26 and 27 are interposed in the first port 22 and the second port 23, respectively.

A mounting hole 31 for the raising pilot check valve 16 is formed in the left and right upper end portion of the body 21 in the left-right direction. The mounting hole 31 is referred to as a cylinder side port (hereinafter referred to as a third port) of the raising side oil passage 11. 29) has been established.
As shown in FIG. 3, the third port 29 is connected to the raising side hydraulic chamber 5 a of the cylinder 5, and a throttle 30 is formed at a connection portion with the mounting hole 31 of the third port 29. .
A plug 33 is screwed into the attachment hole 31 from the left end, and a seal member 32 is interposed between the inner periphery of the attachment hole 31 and the outer periphery of the plug 33.
A valve chamber 34 is formed on the extension of the center line of the mounting hole 31 in the body 21 so as to communicate with the hollow portion of the mounting hole 31, and the third port 29 is provided in the hollow portion of the mounting hole 31 in the valve chamber 34. And communicates with each other through a diaphragm 30.
A valve port 35 is opened on the right side of the valve chamber 34 in the body 21 so as to face the mounting hole 31, and a valve seat 36 is formed around the valve port 35. A valve body 37 made of a ball is disposed in the valve chamber 34 so as to be seated on and off the valve seat 36 to open and close the valve port 35.
A spring insertion hole 38 is recessed in the plug 33, and a valve spring 39 that constantly urges the valve body 37 in the direction in which the valve body 37 is seated on the valve seat 36 is interposed between the spring insertion hole 38 and the valve body 37. It is installed.

A communication hole 40 is opened on the right side of the valve port 35 in the body 21 so as to communicate with the valve port 35, and one end of a communication passage 42 is connected to the communication hole 40 via a throttle 41.
The other end of the communication passage 42 is connected to the first port 22.

A cylinder chamber 43 is formed on the right side of the communication hole 40 in the body 21, and a pilot piston 44 is slidably fitted in the cylinder chamber 43 in the left-right direction. A valve rod 45 is provided on the left end surface of the pilot piston 44 so as to protrude leftward. The valve rod 45 is inserted into the communication hole 40 and the valve port 35 and faces the valve element 37. The pilot piston 44 is always urged by a spring 46 in a direction away from the valve body 37.
A pressure chamber 47 is formed on the right side of the pilot piston 44 in the cylinder chamber 43, and the pressure chamber 47 is closed by a plug 48 screwed into the right end portion. One end of a pilot passage 49 is connected to the pressure chamber 47, and the pilot piston 44 is urged to the left by the pressure in the pressure chamber 47, that is, the pilot passage 49.
The pilot passage 49 is connected to the lower oil passage 12 (see FIGS. 3 and 4).

A mounting hole 51 for the lower pilot check valve 17 is opened in the left-right direction at the lower right end of the body 21 of the valve unit 20, and a plug 53 is screwed into the mounting hole 51 from the right end. A seal member 52 is interposed between the inner periphery of the hole 51 and the outer periphery of the plug 53.
A valve chamber 54 is formed on the extension of the center line of the mounting hole 51 in the body 21 so as to communicate with the hollow portion of the mounting hole 51, and a valve port 55 is hollow in the mounting hole 51 at the left end of the valve chamber 54. It is established to communicate with the department. A valve seat 56 is formed around the valve port 55, and a valve body 57 made of a ball is disposed in the valve chamber 54 so as to be attached to and detached from the valve seat 56 to open and close the valve port 55.
A spring insertion hole 58 is recessed in the plug 53, and a valve spring 59 that constantly urges the valve body 57 in a direction in which the valve body 57 is seated on the valve seat 56 is interposed between the spring insertion hole 58 and the valve body 57. It is installed.
A communication hole 60 is opened on the left side of the valve port 55 in the body 21 so as to communicate with the valve port 55, and the second port 23 is connected to the communication hole 60 via a throttle 61.
On the other hand, one end of the communication passage 62 is connected to the bottom of the mounting hole 51 corresponding to the opposite side of the valve port 55 of the valve chamber 54, and the other end of the communication passage 62 is the cylinder of the raising side pilot check valve 16. It is connected to the pipe 50 via the pressure chamber 47 of the chamber 43.

A cylinder chamber 63 is formed on the left side of the communication hole 60 in the body 21, and a sleeve 63 </ b> A is slidably fitted in the cylinder chamber 63 in the left-right direction. A pilot piston 64 is slidably fitted in the sleeve 63A in the left-right direction.
A valve rod 65 projects rightward from the right end surface of the pilot piston 64, and the right end portion of the valve rod 65 is inserted into the communication hole 60 and the valve port 55 so as to face the valve element 57. The pilot piston 64 is always urged by a spring 66 in a direction away from the valve body 57.
A pressure chamber 67 is formed on the left side of the pilot piston 64 in the cylinder chamber 63, and the pressure chamber 67 is closed by a plug 68 screwed into the left end portion. One end of a pilot passage 69 is connected to the pressure chamber 67, and the pilot piston 64 is urged to the right by an increase in the pressure of oil flowing in the pressure chamber 67, that is, the pilot passage 69.
The pilot passage 69 is connected to the raising side oil passage 11 as shown in FIG.

As shown in FIG. 4, there is a 2-port, 2-position / pilot switching valve (see FIG. 3) between the raising side pilot check valve 16 and the lowering side pilot check valve 17 in the body 21 of the valve unit 20. ) Is arranged so as to extend in the left-right direction.
That is, the body 21 is provided with an installation hole 71 for the poppet valve 70 extending in the left-right direction. The left end of the installation hole 71 is closed by a plug 72 screwed into the left end portion. A communication port 73 is formed at the right end portion of the installation hole 71, and one end of a communication pipe 74 is connected to the communication port 73.
As shown in FIG. 3, the other end of the communication pipe 74 is connected to a communication port (hereinafter referred to as a hydraulic chamber side communication port) 5 c provided in the lower side hydraulic chamber 5 b of the tilt cylinder 5. The hydraulic chamber side communication port 5c is opened at a position near the raising side hydraulic chamber 5a in the lower side hydraulic chamber 5b.
A valve port 75 is formed on the left side of the communication port 73 in the installation hole 71, and a valve seat 76 is formed around the left end of the valve port 75. A valve chamber 78 is formed on the left side of the valve seat 76 in the installation hole 71, and a cone-shaped valve body 77 is attached to and detached from the valve seat 76 to open and close the valve port 75. Has been placed. One end of a communication passage 79 is connected to the valve chamber 78, and the other end of the communication passage 79 is connected to the raising side hydraulic chamber 5a.

A small diameter cylinder chamber 80 is formed on the left side of the valve chamber 78 in the installation hole 71, and a large diameter cylinder chamber 81 is formed on the left side of the small diameter cylinder chamber 80. A valve rod 82 that is formed integrally with the valve body 77 and moves is inserted into the small diameter cylinder chamber 80, and a piston 83 that is formed integrally with the valve rod 82 is disposed on the left side of the valve rod 82. It is formed so as to straddle 80 and the large-diameter cylinder chamber 81. The left end of the piston 83 is opposed to the protrusion 72 a of the plug 72 at the position of the communication passage 85.
One end of a communication passage (pilot passage) 84 is connected to the small diameter cylinder chamber 80, and the other end of the communication passage 84 is connected to the cylinder chamber 63 of the lower pilot check valve 17.
One end of a communication passage (pilot passage) 85 is connected to the large-diameter cylinder chamber 81, and the other end of the communication passage 85 is connected to the first port 22 via the pressure chamber 67 of the lower pilot check valve 17. ing.

  Next, the operation will be described.

When the truck is traveling on the road, as shown in FIG. 9, the tilting cylinder device 3 has the standard position Hs as a reference and is located between the uppermost point Hmax and the lowermost point Hmin in any direction. Random expansion and contraction (lost motion) prevents the tilt cylinder device 3 from resisting free movement of the cab 1 while traveling, thereby preventing the ride comfort from deteriorating.
When the cab 1 rises in the direction of the highest point Hmax during the lost motion, the piston 4a of the tilt cylinder device 3 moves toward the cab 1 as shown in FIGS. The pressure oil in the side hydraulic chamber 5 b is pushed out from the communication port 5 c to the communication pipe 74 and flows into the raising side hydraulic chamber 5 a via the valve port 75, the valve chamber 78 and the communication passage 79 of the poppet valve 70.
At this time, the pressure oil flowing from the lower hydraulic chamber 5 b through the pipe 50 to the communication passage 62 is blocked by the lower pilot check valve 17.
On the other hand, when the cab 1 is lowered in the direction of the lowest point Hmin, the piston 4a of the tilt cylinder device 3 moves to the frame 2 side, so that the pressure oil in the raising side hydraulic chamber 5a is pushed out to the communication passage 79, It flows into the lower hydraulic chamber 5 b via the valve chamber 78, the valve port 75 and the communication pipe 74 of the poppet valve 70.
At this time, the pressure oil flowing from the raising side hydraulic chamber 5 a to the communication passage 42 through the third port 29 is blocked by the raising side pilot check valve 16.
Here, since the volume of the raising side hydraulic chamber 5a is larger than the volume of the lowering side hydraulic chamber 5b by the amount of the piston rod 4, the amount of pressure oil flowing into the lowering side hydraulic chamber 5b from the raising side hydraulic chamber 5a. Therefore, pilot pressure is generated in the pilot passage 49.
Since the pilot pilot pressure opens the pilot pilot check valve 16, excess hydraulic oil in the hydraulic hydraulic chamber 5 a flows into the tank 14 via the pilot pilot valve 16 and escapes.

When the cab 1 is tilted up, the cab lock device 6 shown in FIG. 2 is released by the manual lever 6d.
As shown in FIG. 3, the switching lever 15a of the switching valve 15 is switched to the tilt-up side, the pump port P of the switching valve 15 is connected to the load port a, and the tank port T is connected to the load port b. The
Next, when the pump switch is turned on and the motor M rotates and the pump 13 is driven, the pressure oil of the pump 13 is pumped to the load port a of the raising side oil passage 11 by the switching valve 15 in FIG. .
The pressure oil pumped to the load port a of the raising side oil passage 11 flows into the raising side hydraulic chamber 5a of the cylinder 5 of the tilting cylinder device 3 through the raising side pilot check valve 16 to operate the piston rod 4 to extend. Thus, the cab 1 is lifted from the frame 2 and tilted up.

At this time, in order to extend the piston rod 4, it is necessary to discharge the pressure oil in the lower hydraulic chamber 5 b of the cylinder 5.
In this embodiment, when the hydraulic pressure in the pilot passage 69 of the raising side oil passage 11 becomes equal to or higher than the pilot pressure value set in the lowering side pilot check valve 17, the pilot piston 64 moves rightward in FIG. Then, the valve element 57 of the lower pilot check valve 17 is pushed by the valve rod 65 to be separated from the valve seat 56 and the valve port 55 is opened.
In FIG. 3, when the lower side pilot check valve 17 is opened, the pressure oil in the lower side hydraulic chamber 5b of the cylinder 5 is lowered to the lower side pilot check valve 17 of the lower side oil passage 12, the load port b of the switching valve 15, and the tank. It is discharged to the tank 14 via the port T. Therefore, the piston rod 4 of the tilt cylinder device 3 can be extended to tilt the cab 1 up.

By the way, in the initial stage of the extension operation of the piston rod 4, the raising side hydraulic chamber 5a and the lowering side hydraulic chamber 5b are communicated by the communication pipe 74, so that the pressure oil supplied to the raising side hydraulic chamber 5a communicates. It will flow into the lower hydraulic chamber 5b through the pipe 74.
Therefore, in the present embodiment, the passage of the communication pipe 74 is blocked by the poppet valve 70 provided in the communication pipe 74 so that the pressure oil supplied to the raising side hydraulic chamber 5a is lowered through the communication pipe 74. It was supposed to prevent the fluid from flowing into the side hydraulic chamber 5b.
That is, in FIG. 4, the pressure oil supplied from the raising side oil passage 11 to the first port 22 flows into the large-diameter cylinder chamber 81 of the poppet valve 70 via the communication passage (pilot passage) 85, thereby causing the piston 83. The valve body 77 formed integrally with the piston 83 via the valve rod 82 is seated on the valve seat 76, closes the valve port 75, and shuts off the communication pipe 74.
At this time, if the lower pilot check valve 17 is opened by the pilot pressure in the pilot passage 69 before the poppet valve 70 is closed, the closing operation of the poppet valve 70 is not executed.
Therefore, in the present embodiment, the following devices are devised.
That is, it is necessary that the pilot check valve 17 in the lower oil passage 12 is not opened before the poppet valve 70 is closed. For this purpose, a pressure that allows the poppet valve 70 to move to the right by overcoming the resistance of the O-rings mounted on the valve rod 82 and the piston 83 of the poppet valve 70 is connected to the hydraulic circuit connecting passage (pilot passage). ) 85.
Therefore, by setting the valve opening pressure of the pilot check valve 17 to 2.4 MPa and providing the poppet valve 70 with a large diameter portion and a small diameter portion and changing the pressure receiving area, the pressure oil in the large diameter cylinder chamber 81 is changed. The poppet valve 70 is configured to generate a thrust force that reliably moves the poppet valve 70 to the right due to the difference between the force generated in the poppet valve 70 and the force generated in the poppet valve 70 by the pressure oil in the valve chamber 78.

When the pump switch is turned off and the pump 13 is stopped, due to internal oil leakage from the manual switching valve 15 or the like of the pump 13, the pressure of the raising side oil passage 11 is lowered, and the raising side pilot check valve 16 is turned off. Since the body 37 is also seated on the valve seat 36, the tilt cylinder 5 cannot be shortened.
Further, the hydraulic pressure of the pilot passage 69 in the lower pilot check valve 17 shown in FIG. 4 becomes equal to or less than the set pilot pressure value. As a result, since the pilot piston 64 returns to the left, the valve element 57 is seated on the valve seat 56 and the valve port 55 is closed.
When the lower side pilot check valve 17 is closed, the pressure oil in the lower side hydraulic chamber 5b of the cylinder 5 cannot be discharged, so that the piston rod 4 of the tilt cylinder device 3 cannot be extended.

When the cab 1 is tilted down, the switching lever 15a of the switching valve 15 is switched to the tilt-down side, and the pump port P of the switching valve 15 is connected to the load port b as shown in FIG. Tank port T is connected to load port a.
Next, when the pump switch is turned on and the pump 13 is driven by the motor M, the pressure oil of the pump 13 is pumped to the load port b of the lower side oil passage 12.
The pressure oil pressure-fed to the load port b of the lower side oil passage 12 flows into the lower side hydraulic chamber 5b of the cylinder 5 of the tilt cylinder device 3 through the lower side pilot check valve 17, and shortens the extended piston rod 4. By doing so, the cab 1 is tilted down.

At this time, in order for the piston rod 4 to perform a shortening operation, it is necessary to discharge the pressure oil in the raising side hydraulic chamber 5 a of the cylinder 5.
In the present embodiment, when the pressure in the pilot passage 49 of the raising side pilot check valve 16 becomes 0.6 MPa or more which is the pilot pressure value set in the raising side pilot check valve 16, FIG. 5 and FIG. As shown, the pilot piston 44 is moved to the left by the acting force of the pressure in the pilot passage 49, so that the valve element 37 of the lift-up pilot check valve 16 is pushed by the valve rod 45 and the valve seat 36. The valve port 35 is opened.

  In FIG. 5, when the raising side pilot check valve 16 is opened, the pressure oil in the raising side hydraulic chamber 5 a of the cylinder 5 is discharged to the tank 14 via the raising side pilot check valve 16 and the load port a of the switching valve 15. Therefore, the piston rod 4 of the tilt cylinder device 3 can be shortened to tilt the cab 1 down. When the pump switch is turned on when the cab 1 is tilted down, the poppet valve 70 is pumped to the small diameter cylinder chamber via the load port b of the lower oil passage 12 and the communication passage (pilot passage) 84 in FIG. It moves to the left by the pressurized oil. Thereby, the channel | path of the connection piping 74 returns from a interruption | blocking state to a communication state.

By the way, at the end of the shortening operation of the piston rod 4, as shown in FIG. 7, the lower hydraulic chamber 5 a and the lower hydraulic chamber 5 b are communicated by the communication pipe 74. The pressure oil supplied to 5b flows into the upward hydraulic chamber 5a through the communication pipe 74, and the piston rod 4 of the tilt cylinder device 3 loses the force for differential shortening.
However, since the own weight of the cab 1 is applied to the piston rod 4, the shortening operation continues, and the spring of the four springs supporting the cab 1 and the own weight of the cab 1 applied to the piston rod 4 are continued. At the time when the force is balanced, that is, at the standard position during traveling, the vehicle stops (state Hs in FIG. 9).
Generally, a cabbutylt operator keeps turning on a pump switch while the cab is moving, and turns off the pump switch when the cab 1 is stopped (Hs state in FIG. 9).
Even if the switch of the pump 13 is turned off at the time when the raising side hydraulic chamber 5a and the lowering side hydraulic chamber 5b are communicated by the communication pipe 74, the own weight of the cab 1 is applied to the piston rod 4. The shortening operation continues to the time when the application of the own weight stops, that is, the standard position during traveling.
In addition, when the raising side hydraulic chamber 5a and the lowering side hydraulic chamber 5b are communicated by the communication pipe 74, the piston rod 4 has a force generated in the piston rod 4 by the pressure oil in the lowering side hydraulic chamber 5b, and the raising side Due to the difference from the force generated in the piston rod 4 by the pressure oil in the hydraulic chamber 5a, the piston rod 4 is subjected to an extending force, contrary to the conventional one.
However, the pressure oil in the lower side hydraulic chamber 5b and the higher side hydraulic chamber 5a has a pilot pressure value of 0.6 MPa set in the higher side pilot check valve 16, so that the extension force is weak and the cab 1 is tilted up. Never happen.

  When the pump switch is turned off and the pump 13 is stopped, the oil pressure in the raising side oil passage 11 decreases due to internal oil leakage from the manual switching valve 15 of the pump, etc., so that the raising side pilot reverse direction shown in FIG. The hydraulic pressure of the pilot passage 49 in the stop valve 16 becomes lower than the set pilot pressure value. As a result, since the pilot piston 44 returns to the right, the valve element 37 is seated on the valve seat 36 and the valve port 35 is closed.

  According to the embodiment, the following effects can be obtained.

1) By providing communication piping that connects the raising side hydraulic chamber and the lowering side hydraulic chamber to each other, when the truck is traveling on the road, the hydraulic oil in the raising side hydraulic chamber and the lowering side hydraulic chamber can be moved back and forth. Since the lost motion can be created, it is possible to prevent the tilt cylinder device from obstructing the free movement of the traveling cab and deteriorating the riding comfort of the suspension cab.

2) By installing a poppet valve in the communication pipe, the passage of the communication pipe is blocked without any gap by the poppet valve when the tilt cylinder device is extended, and the pressure oil supplied to the lift side hydraulic chamber Since it can be prevented from flowing into the lower hydraulic chamber through the communication pipe, the double-acting cylinder enables lost motion and reliably prevents oil leakage in the communication pipe during up-loading. Can do. In addition, the weight of the tilt cylinder device can be reduced compared to the differential cylinder.

3) A poppet valve that shuts off the pilot check valve and the communication pipe that are installed in the up-side supply / discharge oil passage and the communication piping is integrated as a valve unit and attached to one end of the cylinder. The tilt cylinder device can be formed compactly.

4) The pilot check valve installed in the lower supply / discharge oil passage is designed to be opened only after the poppet valve shuts off the communication pipe when the tilt cylinder device is extended. The pressure oil supplied to the hydraulic chamber does not flow into the lower hydraulic chamber even if the pump discharge amount or the viscosity of the hydraulic oil changes, and the tilt can be reliably tilted up.

5) By providing the poppet valve with a small-diameter cylinder chamber and a large-diameter cylinder chamber, the poppet valve can be moved with a large thrust, and the valve port can be quickly and reliably closed by the valve body. It is possible to reliably increase the thrust during the extension operation.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

For example, the valve unit is not limited to being directly installed at one end of the cylinder, but may be installed in the vicinity of the cylinder.
In addition, the poppet valve is not limited to being installed on the body of the valve unit, and may be installed in another location.

It is a side view which shows the carbylate apparatus which is one embodiment of this invention. 1 is a perspective view showing a cab on which a cabylt device and a cab lock device according to an embodiment of the present invention are mounted. FIG. It is a hydraulic circuit figure at the time of tilting up the cab of the carbylating apparatus which is one embodiment of this invention. The valve unit is shown, and it is an expanded sectional view which follows the IV-IV line of FIG. 9, and the position of an internal valve respond | corresponds to the hydraulic circuit of FIG. It is a hydraulic circuit diagram at the time of tilting down the cab. The valve unit is shown, and the position of the internal valve corresponds to the hydraulic circuit of FIG. It is a hydraulic circuit diagram in case a carbylt apparatus is in the state of a lost motion. The valve unit is shown, and the position of the internal valve corresponds to the hydraulic circuit of FIG. It is a partially omitted side view showing a valve unit and a communication pipe of the tilt cylinder device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cab, 1a ... Supporting point, 2 ... Frame, 3 ... Cylinder apparatus for tilting, 4 ... Piston rod, 4a ... Piston, 5 ... Cylinder for tilting, 5a ... Frame side hydraulic chamber (raising side hydraulic chamber), 5b ... Cab Side hydraulic chamber (lower side hydraulic chamber), 5c ... Communication port (hydraulic chamber side communication port), 6 ... Cab lock device, 6a ... Rear arch, 6b ... Coil spring, 6c ... Floating bar, 6d ... Cablock release lever, 6e ... switch, 7 ... check valve, 8 ... filter, 9, 9a ... relief valve, 10 ... hydraulic drive circuit, 11 ... up-side supply / discharge oil passage (up-side oil passage), 12 ... lower-side supply / discharge oil passage ( Lower oil path), 13 ... Pump, 14 ... Tank, 15 ... Manual switching valve (switching valve), 15a ... Switching lever, 16 ... Raising pilot check valve, 17 ... Lower pilot check valve, 20 ... Valve Unit, 2 ... Body, 22 ... First port (switching valve side port of raising side oil passage), 23 ... Second port (switching valve side port of lowering side oil passage), 24,25 ... Female thread part, 26,27 ... Filter, 29 ... Third port (cylinder side port of the raising oil passage), 30 ... Restriction, 31 ... Mounting hole, 32 ... Seal member, 33 ... Plug, 34 ... Valve chamber, 35 ... Valve port, 36 ... Valve seat, 37 ... valve body, 38 ... spring insertion hole, 39 ... valve spring, 40 ... communication hole, 41 ... throttle, 42 ... communication passage, 43 ... cylinder chamber, 44 ... pilot piston, 45 ... valve rod, 46 ... spring, 47 ... Pressure chamber, 48 ... plug, 49 ... pilot passage, 50 ... piping, 51 ... mounting hole, 52 ... seal member, 53 ... plug, 54 ... valve chamber, 55 ... valve port, 56 ... valve seat, 57 ... valve body, 58 ... Spring insertion hole, 59 ... Valves Ring, 60 ... Communication hole, 61 ... Restriction, 62 ... Communication passage, 63 ... Cylinder chamber, 63A ... Sleeve, 64 ... Pilot piston, 65 ... Valve rod, 66 ... Spring, 67 ... Pressure chamber, 68 ... Plug, 69 ... Pilot passage, 70 ... Poppet valve, 71 ... Installation hole, 72 ... Plug, 72a ... Projection, 73 ... Communication port, 74 ... Communication pipe (communication passage), 75 ... Valve port, 76 ... Valve seat, 77 ... Valve body 78 ... Valve chamber, 79 ... Communication passage, 80 ... Small diameter cylinder chamber, 81 ... Large diameter cylinder chamber, 82 ... Valve rod, 83 ... Piston, 84 ... Communication passage (pilot passage), 85 ... Communication passage (pilot passage) .

Claims (5)

A tilt cylinder device that is interposed between the cab and the frame and tilts the cab; a raising-side supply / discharge oil passage that supplies or discharges pressure oil to the frame-side hydraulic chamber of the tilt cylinder device;
A lower-side supply / discharge oil passage for supplying or discharging pressure oil to the cab-side hydraulic chamber of the tilt cylinder device;
A pilot check valve interposed in each of the up-side supply / discharge oil passage and the down-side supply / discharge oil passage; a communication passage for communicating the frame-side hydraulic chamber and the cab-side hydraulic chamber with each other;
A poppet valve that blocks the communication path when the tilt cylinder device is extended and prevents the pressure oil supplied to the frame-side hydraulic chamber from flowing into the cab-side hydraulic chamber through the communication path;
A cabylt device characterized by comprising:   A valve unit is provided at or near the end of the tilt cylinder device. The valve unit includes a pilot check valve interposed in the up-side supply / discharge oil passage and the down-side supply / discharge oil. The pilot check valve interposed in the road and the poppet valve interposed in the communication path between the frame side hydraulic chamber and the cab side hydraulic chamber are integrally formed. Item 2. The carbylt device according to item 1.   During the extension operation of the tilt cylinder device, the valve opening pressure of the pilot check valve interposed in the lower-side supply / discharge oil passage is in the communication path between the frame-side hydraulic chamber and the cab-side hydraulic chamber. 3. The carbitol device according to claim 1, wherein the inserted poppet valve is set so as to open only after the communication path is blocked.   The cabylt device according to claim 1, 2 or 3, wherein the poppet valve is configured as a 2-port, 2-position, pilot switching valve.   The cabylt apparatus according to claim 4, wherein the pilot switching operation portion of the poppet valve includes a small diameter cylinder chamber and a large diameter cylinder chamber.

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