JP2019025958A - Load-carrying platform mobile transport vehicle - Google Patents

Abstract

To provide a load-carrying platform mobile transport vehicle in which buckling deformation of a piston rod can be suppressed at the time of extension drive of a cylinder for longitudinal movement of a load-carrying platform.SOLUTION: A load-carrying platform mobile transport vehicle is provided with: a load-carrying platform 4 which is so supported as to be movable in a vehicle cross direction with respect to a chassis frame 11 of a vehicle 1; an expansion cylinder 51 which is interposed between the load-carrying platform 4 and the chassis frame 11, moves the load-carrying platform 4 to the rear of the vehicle by extension drive thereof and moves the load-carrying platform 4 to the front of the vehicle by contraction drive thereof; and a hydraulic circuit 70 which can supply a hydraulic pressure to and discharge the same from the expansion cylinder 51. In this load-carrying platform mobile transport vehicle, the hydraulic circuit 70 is provided with a differential circuit 75d which communicates a contraction side chamber 52b and an extension side chamber 52a, which are partitioned by a piston 51b of the expansion cylinder 51, with each other at the time of extension drive of the expansion cylinder 51.SELECTED DRAWING: Figure 4

Description

  The present disclosure relates to a load carrier mobile vehicle.

Conventionally, like a vehicle carrier, the platform can be moved to a loading platform storage position where the loading platform is placed on the chassis, and a loading position where the loading platform can slide to the rear of the vehicle relative to the chassis to load and unload loads. A transport vehicle is known (see, for example, Patent Document 1 and Patent Document 2).
In this conventional loading platform mobile vehicle, the loading platform is supported so as to be slidable in the longitudinal direction of the vehicle with respect to the chassis, and a hydraulic cylinder for longitudinal sliding that can be expanded and contracted in the sliding direction of the loading platform is provided between the chassis and the loading platform. It has a structure.
The front / rear slide hydraulic cylinder includes a tube, a piston and a piston rod that are slidably movable in the tube, and a shortened side chamber and an extended side chamber defined by the piston in the tube.
Both liquid chambers are connected to a switching valve that supplies and discharges hydraulic pressure. This switching valve supplies hydraulic pressure to the expansion side chamber, drains the hydraulic pressure of the shortening side chamber, fixed position that seals both liquid chambers, drains the hydraulic pressure of the expansion side chamber, and supplies hydraulic pressure to the shortening side chamber And a shortened side position.

  Therefore, when the switching valve is set to the extension side position, the hydraulic cylinder is driven to extend, and accordingly, the cargo bed slides rearward of the vehicle. When the switching valve is set to the shortened position, the hydraulic cylinder is shortened and the loading platform slides forward of the vehicle and is disposed on the chassis. When the switching valve is set to a fixed position, the piston is fixed, the state of the hydraulic cylinder is maintained, and the cargo bed is fixed.

JP 2008-230384 A Japanese Patent Laid-Open No. 2006-84829

However, the above-described conventional technology has the following problems to be solved.
In the above-described carrier transporting vehicle, the required drive oil pressure is determined based on the shortened drive time of the hydraulic cylinder. That is, in the piston, the pressure receiving area of the shortened side chamber is narrower by the cross-sectional integral of the piston rod than the pressure receiving area of the extension side chamber, and the obtained driving force is reduced. Therefore, at the time of this shortening driving, it is necessary to set the loading platform on which the article is carried to a driving force that can move.
As described above, when the drive hydraulic pressure of the hydraulic cylinder is determined based on the operation at the time of shortening drive, the piston pressure receiving area becomes larger at the time of extension driving than at the time of shortening, and the extension driving force of the hydraulic cylinder is larger than the shortening driving force. Become.

Therefore, when the loading platform is slid to the rear of the vehicle by the extension drive of this hydraulic cylinder, if the loading platform is caught by unevenness on the ground and the sliding is restricted, the load in the buckling direction acts greatly on the piston rod, There was a risk of the piston rod buckling. In order to prevent this, it is necessary to improve rigidity such as increasing the diameter of the piston rod, or to add a new member such as a relief valve.
However, in the former case, the hydraulic cylinder may be increased in size and weight, and the pressure receiving area on the shortened side chamber side of the piston may be reduced, and the shortened driving force may be reduced. In the latter case, there is a risk of increasing the cost such as an increase in the number of parts.

  The present disclosure has been made in view of the above circumstances, and an object of the present disclosure is to provide a load carrier movable transport vehicle that can suppress buckling deformation of a piston rod when a cylinder for front and rear movement of the load carrier is driven to extend.

The loading platform mobile vehicle of the present disclosure is:
A loading platform supported so as to be movable in the longitudinal direction of the vehicle with respect to the vehicle chassis,
A forward / backward movement cylinder interposed between the loading platform and the chassis, moving the loading platform rearward by extension driving, and moving the loading platform forward by shortening driving;
A fluid pressure circuit capable of supplying fluid pressure to the forward / backward movement cylinder and capable of discharging the fluid pressure;
A load carrier mobile carriage equipped with
A loading platform moving type in which the fluid pressure circuit is provided with a differential circuit that communicates the shortened side chamber and the stretched side chamber defined by the piston of the forward / backward movement cylinder when the forward / backward movement cylinder is extended. It is a transport vehicle.

Therefore, in the loading platform mobile vehicle of the present disclosure, when the loading platform is moved to the rear of the vehicle by the extension drive of the front / rear movement cylinder, the shortening side chamber and the extension side chamber are brought into communication with each other by the differential circuit, and both chambers are kept at the same pressure. To do.
Thereby, the cylinder for back-and-forth movement performs extension driving based on the pressure-receiving surface difference of the piston in the cross-sectional integral of the piston rod. In this case, the extension driving force of the cylinder for back and forth movement can be kept low compared to the case where the shortened side chamber is drained, and the piston rod is moved when the loading platform is restricted by the unevenness of the ground. The acting buckling force can be suppressed and the buckling deformation of the piston rod can be suppressed.

It is the schematic of the state which looked at the carrier movable transport vehicle of Embodiment 1 from the vehicle left side, Comprising: The state which has arrange | positioned the carrier to the carrier storage position is shown. It is the schematic of the state which looked at the loading platform mobile carrier vehicle of Embodiment 1 from the vehicle left side, Comprising: The tilting frame is inclined to normal inclination angle, The state which retracted the loading platform to the general vehicle loading position is shown. FIG. 3 is a schematic view of the loading platform mobile transport vehicle according to the first embodiment as viewed from the left side of the vehicle, showing a state in which the tilting frame is tilted at a gentle tilt angle and the loading platform is moved back to the low vehicle height loading position. . FIG. 3 is a circuit diagram showing a hydraulic circuit of the platform mobile transport vehicle of the first embodiment. FIG. 6 is a circuit diagram showing a hydraulic circuit of a platform mobile transporter according to a second embodiment.

Hereinafter, the best mode for realizing the carrier transporting vehicle of the present disclosure will be described with reference to the drawings.
(Embodiment 1)
Below, the carrier mobile carrier A of Embodiment 1 is demonstrated.
1 to 3 are schematic views of the loading platform mobile carrier A according to Embodiment 1 as viewed from the left side of the vehicle.

  As shown in FIG. 1, the carrier mobile vehicle A includes a vehicle 1 having a pair of left and right chassis frames (chassis) 11 and guide rails 2 (a pair of left and right chassis) fixed to a subframe 12 on each chassis frame 11. A pair of left and right tilt frames 3 supported at the rear end portion of the sub-frame 12 in a tiltable manner, a load platform 4 supported on each tilt frame 3 so as to be movable in the longitudinal direction of the vehicle, and a load platform 4 Tilt that has a telescopic cylinder (cylinder for back and forth movement) 51 that moves in the vehicle longitudinal direction with respect to the tilting frame 3 and tilts the tilting frame 3 together with the loading platform 4 with respect to the guide rail 2 by the telescopic movement of the telescopic cylinder 51 And a device 5.

  Each guide rail 2 is continuously formed with an upward inclined portion 21 inclined upward at the front portion, a horizontal portion 22 at the intermediate portion, and a downward inclined portion 23 inclined downward at the rear portion. .

  Each tilt frame 3 is pivotally supported (pivot support portion 8) so as to be tiltable on the rear end portion of the sub frame 12 at a position slightly rearward from the central portion in the length direction. The pivot portion 8 is a pivot shaft 83 pivotally supported on a bracket provided on the lower surface of the tilt frame 3 by a bracket provided at the rear end portion of the sub frame 12.

  A downward supporting leg 9 is attached to the rear end of each tilting frame 3. As will be described later, the support legs 9 contact the ground G and support the rear end portion of the tilting frame 3 when the tilting frame 3 is in the maximum rearward tilting posture (FIG. 3).

  The loading platform 4 has two left and right bottom frames (hereinafter referred to as vertical joists) 42 on the lower surface of the vehicle mounting platform 41. Grounding rollers 43 are attached to the lower surface of the rear end portion of the vehicle mounting base 41 at positions closer to the left and right outer ends, respectively. A pair of left and right edge plates 44 are attached to the rear end of the loading platform 4 so as to be raised and lowered.

  The moving body 6 is pivotally supported by a support shaft 64 at the front end portion of the vertical joist 42 on the bottom surface of the loading platform. The moving body 6 is movable along the tilting frame 3 and can be moved back and forth by the telescopic cylinder 51. The loading platform 4 can be moved in the vehicle front-rear direction with respect to the tilting frame 3 via the moving body 6.

  The tilting device 5 includes left and right guide rails 2, one telescopic cylinder 51, and a tilt frame tilting roller (hereinafter referred to as “rolling frame”) attached to the tube 52 of the telescopic cylinder 51 and moving along the guide rail 2. (Simply referred to as a tilting roller) 55. The tilting roller 55 is attached to the lower end of a downward arm 54 provided on the tube 52 of the telescopic cylinder 51. The telescopic cylinder 51 includes a piston rod 51a (the piston rod 51a is shown in FIGS. 2 and 3) and a tube 52, and the tip of the piston rod 51a is fixed to the front end of the tilting frame 3. The tube 52 is supported so as to be movable in the vehicle front-rear direction along the tilting frame 3.

  The tilting device 5 expands and contracts the telescopic cylinder 51 (the tube 52 moves back and forth), and the tilting roller 55 moves back and forth along the guide rail 2 together with the tube 52, so that the tilting frame 3 is moved to the loading platform. 4 and can be moved in the vehicle front-rear direction with respect to the tilting frame 3 via the movable body 6.

  In the same manner as described in Japanese Patent Application Laid-Open No. 2008-207573, this loading platform mobile vehicle is adjusted by adjusting the extension amount of the telescopic cylinder 51 from the loading platform storage position in FIG. Is set to two kinds of inclination angles, that is, a normal inclination angle (about 10 °) for loading a normal vehicle height shown in FIG. 2 and a gentle inclination angle (about 6 °) for loading a low vehicle height shown in FIG. It has come to be able to do.

  That is, when the telescopic cylinder 51 is extended from the loading platform storage position in FIG. 1, the tube 52 of the telescopic cylinder 51 moves rearward so that the tilting roller 55 moves rearward along the guide rail 2, thereby While the tilting frame 3 tilts backward together with the loading platform 4, the moving body 6 moves backward and the loading platform 4 moves rearward with respect to the tilting frame 3. As shown in FIG. 2, in the ordinary vehicle loading position where the ground roller 43 at the rear end of the loading platform is in contact with the ground G, the loading platform 4 has a normal inclination angle (about 10 °) for loading a regular vehicle. .

  Further, when the telescopic cylinder 51 is further extended from the state of FIG. 2, the tilting roller 55 moves backward on the horizontal portion 22 of the guide rail 2 to further tilt the tilting frame 3, and the tilting roller 55 is guided. The support leg 9 comes into contact with the ground G when it is located at the entrance of the downward inclined portion 23 of the rail 2. After that, even if the telescopic cylinder 51 is extended, the tilting roller 55 moves in the descending inclined portion 23, so that only the loading platform 4 further moves backward while the tilting frame 3 maintains the maximum rearward tilting posture of FIG. In the state where the telescopic cylinder 51 is fully extended, as shown in FIG. 3, the front end of the loading platform 4 reaches the low vehicle height loading position near the rear end of the tilting frame 3 (substantially low position). 4 is a gentle inclination angle (about 6 °) for loading low and high vehicles.

  In the state of FIG. 3, the front end portion of the loading platform 4 is located near the rear end of the tilting frame 3 (backward from the pivotal support portion 8 of the tilting frame 3), and includes the load at the front end portion of the loading platform (including the weight of the loaded vehicle S). ) Is applied near the rear end of the tilting frame 3, but when the support leg 9 is in contact with the ground G, the load on the front side of the loading platform applied near the rear end of the tilting frame is applied via the support leg 9. Can be supported by the ground G.

  1 to 3, the support leg 9 at the rear end of the tilting frame 3 is placed on the ground G when the tilting frame 3 is in the maximum rearward tilting posture (FIG. 3). The load is applied to the rear end portion of the tilting frame 3 by being grounded. The length of the support leg 9 is such that the load-carrying transport vehicle is placed on a flat ground without any irregularities or steps (the tire contact of the transport vehicle). It is set on the assumption that the ground and the ground contact surface of the support leg 9 are used at the same height.

Next, the telescopic cylinder 51 that moves the loading platform 4 between the “loading platform storage position” and the “low vehicle high vehicle loading position” will be described.
The telescopic cylinder 51 has a well-known structure, and includes a cylindrical tube 52 and a piston rod 51a that can enter and exit the tube 52 as shown in FIG. And the piston 51b which divides the inside of the tube 52 into the shortening side chamber 52b and the expansion | extension side chamber 52a is provided in the base end part of the piston rod 51a.

  Next, a hydraulic circuit 70 as a fluid pressure circuit that supplies hydraulic pressure as fluid pressure for driving the telescopic cylinder 51 will be described.

The hydraulic circuit 70 includes a hydraulic pressure supply circuit 71, a drain circuit 72, an expansion side circuit 73, a shortening side circuit 74, and a switching valve 75.
The hydraulic pressure supply circuit 71 is a circuit that supplies hydraulic pressure from the pump P as a hydraulic pressure supply source (fluid pressure supply source) to the switching valve 75.
The drain circuit 72 is a circuit from the switching valve 75 to the drain tank T, and returns the hydraulic pressure in the expansion side circuit 73, the shortening side circuit 74, and both the chambers 52a and 52b to the drain tank T via the switching valve 75. is there.

  The hydraulic pressure supply circuit 71 and the drain circuit 72 are communicated via a relief circuit 77 having a relief valve 77a. Thereby, when the hydraulic pressure of the hydraulic pressure supply circuit 71 exceeds a preset set pressure, the drain circuit 72 is released, and the hydraulic pressure supply circuit 71 is configured not to exceed the set pressure.

The extension side circuit 73 is a circuit that is connected to the extension side chamber 52 a and supplies and discharges oil to and from the extension side chamber 52 a via the switching valve 75.
The shortening side circuit 74 is a circuit that is connected to the shortening side chamber 52b and supplies / discharges oil to / from the shortening side chamber 52b.

  The switching valve 75 is provided between the hydraulic pressure supply circuit 71 and the drain circuit 72, the extension side circuit 73 and the shortening side circuit 74, and the extension side circuit 73 and the extension side chamber 52a, and the shortening side circuit 74 and the shortening side chamber 52b. And a valve for switching the hydraulic supply / discharge state.

  The switching valve 75 includes a fixed position 75b, which is the position shown in FIG. 4, a shortened side position 75c on the right side of the fixed position in the figure, and an extended side on the left side of the fixed position in the figure. Position 75a.

  The switching valve 75 seals all of the hydraulic pressure supply circuit 71, the drain circuit 72, the extension side circuit 73, and the shortening side circuit 74 at the fixed position 75b. Therefore, in the fixed position 75b, the supply and discharge of oil in both the chambers 52a and 52b of the expansion / contraction cylinder 51 is restricted, whereby the expansion / contraction cylinder 51 is restricted in its expansion and contraction.

  At the shortened side position 75 c of the switching valve 75, the extension side circuit 73 is communicated with the drain circuit 72, and the shortening side circuit 74 is communicated with the hydraulic pressure supply circuit 71. Therefore, in the shortened side position 75c, the hydraulic pressure of the hydraulic pressure supply circuit 71 is supplied to the shortened side chamber 52b, while the oil in the extended side chamber 52a is discharged to the drain circuit 72, and the telescopic cylinder 51 performs the shortening drive.

In the extension position 75 a of the switching valve 75, in the first embodiment, the hydraulic pressure supply circuit 71 is communicated with the extension side circuit 73 and the shortening side circuit 74.
That is, the switching valve 75 includes a differential circuit 75d that brings the expansion side chamber 52a and the shortening side chamber 52b of the telescopic cylinder 51 into communication at the expansion side position 75a.

  Therefore, when the switching valve 75 is set to the expansion side position 75a, the hydraulic pressure of the hydraulic pressure supply circuit 71 is brought into communication between the expansion side chamber 52a and the shortening side chamber 52b, and the hydraulic pressure is supplied to both the chambers 52a and 52b and the shortening side chamber 52b. The fluid discharged from is also supplied to the extension side chamber 52a. At this time, since the extension side chamber 52a and the shortening side chamber 52b have the same pressure, the piston 51b is driven to extend with a pressure receiving area due to a cross-sectional area difference between the pressure receiving area on the extension side chamber 52a side and the pressure receiving area on the shortening side chamber 52b side. I do. In this case, the extension driving force is lower than when the hydraulic pressure is supplied to the extension side chamber 52a and the shortened side chamber 52b is drained.

Next, the operation of the first embodiment will be described.
First, the operation of retracting the loading platform 4 from the loading platform storage position shown in FIG. 1 to the general vehicle loading position shown in FIG. 2 and the low vehicle high vehicle loading position shown in FIG. 3 will be described.
When retracting the loading platform 4 from the loading platform storage position shown in FIG. 1, first, the telescopic cylinder 51 in the shortest state is driven to extend.

In order to drive the telescopic cylinder 51 to extend, the switching valve 75 is moved from the fixed position 75b shown in FIG. 4 to the right in the figure and switched to the extension side position 75a. As a result, the oil is supplied in a state where the hydraulic pressure supply circuit 71 communicates with the extension side circuit 73 and the shortening side circuit 74 via the differential circuit 75d. Therefore, in the expansion / contraction cylinder 51, the extension side chamber 52a and the shortening side chamber 52b have the same pressure, and are driven to extend due to the pressure receiving area difference of the piston 51b.
The oil in the shortened side chamber 52b whose volume is reduced by the extension drive moves to the extension side chamber 52a via the differential circuit 75d in the extension side position 75a.

  Thus, in addition to the supply from the hydraulic pressure supply circuit 71, the expansion side chamber 52a is supplied with the oil corresponding to the volume reduction of the shortening side chamber 52b. Therefore, the expansion cylinder 51 supplies oil only to the expansion side chamber 52a. Compared with, it expands at high speed.

  By the extension drive of the telescopic cylinder 51, the tilting roller 55 moves together with the tube 52 along the guide rail 2 toward the rear of the vehicle, and the tilting frame 3 and the loading platform 4 tilt with respect to the chassis frame 11. The vehicle moves rearward with respect to the tilting frame 3.

  Further, as shown in FIG. 2, when the tilting roller 55 moves to the rear end portion of the horizontal portion 22 and before the descending inclined portion 23 in the guide rail 2, the loading platform 4 is moved to the rear end portion thereof. The ground roller 43 reaches the general vehicle loading position where it contacts the ground G. In this state, a general loading vehicle S having a vehicle height can be loaded.

  Further, when loading a low and high vehicle, the telescopic cylinder 51 is further driven to extend. As a result, the tilting roller 55 moves on the descending inclined portion 23 in the guide rail 2, and the tilting frame 3 loosens the tilt angle from the normal tilt angle to the gentle tilt angle. At the same time, the loading platform 4 moves backward from the general vehicle loading position shown in FIG. 2 to the low vehicle height loading position shown in FIG. Move to the car loading position. Accordingly, the inclination of the loading platform 4 becomes gentle, and the loading vehicle S with a low vehicle height can be loaded.

Here, based on FIG. 2 and FIG. 3, a conventional problem will be described using the configuration of the first embodiment.
In the prior art, when the telescopic cylinder 51 is driven to extend, hydraulic pressure is supplied to the extension side chamber 52 a while the shortening side chamber 52 b is connected to the drain circuit 72. In this case, since the hydraulic pressure received by the entire area of the piston 51b acts in the expansion direction, the expansion cylinder 51 has a large driving force compared to the first embodiment.

  As shown in FIGS. 2 and 3, when the platform 4 moves to the rear of the vehicle with the ground roller 43 in contact with the ground as shown in FIGS. 4 movement may be restricted.

In this case, there is a possibility that the large driving force acts on the telescopic cylinder 51 as a reaction force, the piston rod 51a receives a load in the buckling direction, and the piston rod 51a is deformed.
Further, the extension speed of the telescopic cylinder 51 is a speed corresponding only to the amount of oil supplied from the hydraulic pressure supply circuit 71, and the operator may feel the movement of the loading platform 4 frustrated, and improvement in workability is desired. It was rare.

  On the other hand, in the first embodiment, when the telescopic cylinder 51 is driven on the extension side, only the hydraulic pressure corresponding to the pressure receiving area difference between the extension side chamber 52a side and the shortening side chamber 52b side acts on the piston 51b. Can be kept low. Thereby, when the movement of the loading platform 4 to the rear of the vehicle is restricted by the unevenness of the ground G or the like, the buckling direction force acting on the piston rod 51a can be suppressed low, and the piston rod 51a is prevented from being deformed. be able to.

  In addition, in the first embodiment, when the telescopic cylinder 51 is driven on the extension side, the shortening side chamber 52b and the extension side chamber 52a are communicated with each other by the differential circuit 75d, and the extension side chamber 52a is supplied from the hydraulic pressure supply circuit 71. In addition to the oil, the oil discharged after the volume of the shortened side chamber 52b is reduced is also supplied. For this reason, compared with the case where oil is supplied to the extension side chamber 52a only from the hydraulic pressure supply circuit 71, the amount of oil supplied to the extension side chamber 52a increases, and the extension speed of the extension cylinder 51 can be improved. As a result, the rearward movement speed of the loading platform 4 when the telescopic cylinder 51 is driven to extend can be increased. Therefore, working efficiency can be improved.

  When the loading platform 4 is moved to the on-vehicle position shown in FIG. 2 or the on-vehicle position shown in FIG. 3 to load and unload the loaded vehicle S, the switching valve 75 is fixed to the fixed position 75b. , The loading platform 4 is fixed, and the cover plate 44 is laid down.

Next, the operation of returning the loading platform 4 moved to the high vehicle mounting position shown in FIG. 2 or the low vehicle mounting position shown in FIG. 3 to the loading platform storage position shown in FIG. 1 will be described.
In this case, when the loading of the loaded vehicle S on the loading platform 4 is finished, the strung plate 44 is set in an upright state, and then the telescopic cylinder 51 is driven to be shortened to move the loading platform 4 forward of the vehicle.

  Thus, when moving the loading platform 4 forward of the vehicle, the switching valve 75 is moved from the fixed position 75b to the left in FIG. 4 to switch to the shortened position 75c. As a result, in the telescopic cylinder 51, the shortening side chamber 52 b is communicated with the hydraulic pressure supply circuit 71, while the expansion side chamber 52 a is communicated with the drain circuit 72.

  Accordingly, in the telescopic cylinder 51, the piston 51b receives the pressure in the entire portion facing the shortened side chamber 52b and is driven to shorten. At the time of this shortening drive, the pressure receiving area of the supply hydraulic pressure in the piston 51b depends on the cross-sectional area of the piston rod 51a, but than in the case of receiving pressure in the entire area of the extension side chamber 52a of the piston 51b as described above, The pressure receiving area is a small driving force.

As the telescopic cylinder 51 is shortened, the loading platform 4 moves forward along the tilting frame 3. Then, as the tilting roller 55 shifts from the descending tilt portion 23 to the horizontal portion 22 in the guide rail 2, the tilt angle of the tilt frame 3 changes from the gentle tilt angle shown in FIG. 3 to the normal tilt angle. Furthermore, when the tilting roller 55 rises and reaches the tilted portion 21, the tilting frame 3 is in the horizontal state shown in FIG.
Thereafter, when the telescopic cylinder 51 is shortened to the shortest state, the loading platform 4 is disposed at the loading platform storage position shown in FIG.

  As described above, when the telescopic cylinder 51 is driven to be shortened, the piston 51b receives the hydraulic pressure in the shortened side chamber 52b with a pressure receiving area that is a value obtained by subtracting the cross-sectional area of the piston rod 51a from the cross-sectional area of the piston 51b. Therefore, by setting the pressure receiving area during the shortening drive and the cross-sectional area of the piston rod 51a to be equal, the extension side driving force and the pressure side driving force can be set to be approximately equal.

Therefore, if the pressure is set so that the necessary driving force of the telescopic cylinder 51 can be obtained, the expansion side driving force and the pressure side driving force can be set to substantially the same driving force. On the other hand, the extension side driving force does not become extremely large.
Alternatively, the expansion side driving force is reduced to the compression side driving force by making the cross sectional area of the piston rod 51a smaller than the value obtained by subtracting the cross sectional area of the piston rod 51a from the cross sectional area of the piston 51b, which is the pressure receiving area during shortening driving. It is also possible to keep it lower.
In this way, the degree of freedom for setting the extension side driving force and the compression side driving force is improved.

(Effect of Embodiment 1)
Below, the effect of the carrier mobile vehicle of Embodiment 1 is enumerated.
1) The loading platform mobile transport vehicle of the first embodiment is
A loading platform 4 supported so as to be movable in the longitudinal direction of the vehicle with respect to a chassis frame (chassis) 11 of the vehicle 1;
An extendable cylinder 51 interposed between the loading platform 4 and the chassis frame 11 for moving the loading platform 4 to the rear of the vehicle by extension driving and moving the loading platform 4 to the front of the vehicle by shortening driving;
A hydraulic circuit 70 capable of supplying and discharging hydraulic pressure to the telescopic cylinder 51;
A load carrier mobile carriage equipped with
When the expansion cylinder 51 is driven to extend, the hydraulic circuit 70 is provided with a differential circuit 75d that connects the shortening side chamber 52b and the extension side chamber 52a defined by the piston 51b of the expansion cylinder 51. It was.
Accordingly, when the telescopic cylinder 51 is driven to extend, the shortened side chamber 52b and the extended side chamber 52a are brought into communication with each other by the differential circuit 75d, and the telescopic cylinder 51 is based on the pressure receiving area difference of the piston 51b corresponding to the cross-sectional area of the piston rod 51a. To extend. In this case, as compared with the case where the shortened side chamber 52b is drained, the extension driving force of the telescopic cylinder 51 can be kept low. For this reason, it is possible to suppress the buckling force that acts on the piston rod 51a when the load carrier 4 is slid by the unevenness of the ground, and to suppress the buckling deformation of the piston rod 51a.
In addition, when the telescopic cylinder 51 is driven to extend, oil discharged by reducing the volume of the shortening side chamber 52b is supplied to the extension side chamber 52a via the differential circuit 75d.
Therefore, when the expansion cylinder 51 is driven to extend, the amount of oil supplied to the extension side chamber 52a can be increased compared to that in which the oil in the shortened side chamber 52b is drained, and the extension speed can be increased accordingly. It becomes possible. As a result, the moving speed of the loading platform 4 can be increased without changing the supply state of the hydraulic pressure from the hydraulic circuit 70, and the working efficiency can be improved.

2) The carrier mobile carriage of the first embodiment is
The hydraulic circuit 70 includes a switching valve 75 capable of communicating and blocking between the shortening side chamber 52b and the expansion side chamber 52a, and the hydraulic pressure supply circuit 71 side (pump P side) and the drain circuit 72 side,
The switching valve 75 includes a fixed position 75b that seals the shortening side chamber 52b and the extension side chamber 52a, and a shortening side position 75c that connects the extension side chamber 52a to the drain tank T side while communicating the shortening side chamber 52b to the pump P side. And an extension side position 75a having a differential circuit 75d for connecting the shortening side chamber 52b and the extension side chamber 52a to the hydraulic pressure supply circuit 71 side.
Therefore, the differential circuit 75d can be provided by partially changing the configuration of the switching valve 75 at the extension side position 75a, and the configuration can be simplified.

3) The carrier mobile vehicle of the first embodiment is
On the chassis frame (chassis) 11, a tilt frame 3 that can tilt in a substantially horizontal normal posture and a rearward tilted posture in which the vehicle front side end is raised with respect to the vehicle rear side end extends in the vehicle longitudinal direction. And
The loading platform 4 is supported so as to be movable in the vehicle front-rear direction with respect to the tilting frame 3, and the vehicle rear side end portion (grounding roller 43) of the loading platform 4 is supported so as to be grounded by the extension drive of the telescopic cylinder 51. Yes.
Therefore, when the carrier 4 is moved rearward of the vehicle, the rear end of the carrier 4 is grounded, and the carrier mobile transport vehicle having the carrier 4 that may be restricted in movement due to the unevenness of the ground G has the above effect. Can be obtained.

(Other embodiments)
Next, a description will be given of a load carrier mobile vehicle according to another embodiment.
Note that in the description of other embodiments, components that are the same as those in the other embodiments are denoted by the same reference numerals as those of the present embodiment, and description thereof is omitted. Only differences from the present embodiment will be described.

(Embodiment 2)
The second embodiment is a modification of the first embodiment, and the installation position of the differential circuit is different from that of the first embodiment.
FIG. 5 is a circuit diagram showing a hydraulic circuit 270 in the carrier mobile vehicle according to the second embodiment.

  In the second embodiment, the switching valve 275 has a structure of the extension side position 75a, which is different from that of the first embodiment, and has a general structure. That is, at the extension side position 75a of the switching valve 275, the hydraulic pressure supply circuit 71 and the extension side circuit 73 are communicated, and the shortening side circuit 74 and the drain circuit 72 are communicated. That is, the switching valve 275 has a general 6-port, 3-position valve structure.

A differential valve 200 constituting a differential circuit is provided in the middle of the expansion side circuit 73 and the shortening side circuit 74.
The differential valve 200 includes a shortening side position 200a and an extension side position 200b.

At the shortened side position 200a of the differential valve 200, the hydraulic pressure supply circuit 71 and the shortened side circuit 74 are in communication with each other, while the extension side circuit 73 and the shortened side circuit 74 are disconnected.
Further, in the extension side position 200b, the extension side circuit 73 and the shortening side chamber 52b are communicated with each other, while the shortening side circuit 74 is sealed and cut off from the shortening side chamber 52b. In the extension side position 200b, a circuit portion 275d that allows the extension side circuit 73 and the shortened side chamber 52b to communicate with each other corresponds to a differential circuit. As described above, the differential valve 200 is a general 4-port, 2-position switching valve.

  When the differential valve 200 is not operated, the differential valve 200 is disposed at the shortened position 200a by the urging force, and in conjunction with the switching valve 275 being operated to the extended position 75a, the solenoid is driven to extend the extended position 200b. The switching is controlled so as to be switched.

  Therefore, when the switching valve 275 and the differential valve 200 are set to the expansion side positions 75a and 200b, the hydraulic pressure is supplied from the hydraulic pressure supply circuit 71 to the expansion side chamber 52a via the expansion side circuit 73, and the differential valve 200 is provided. The shortening side chamber 52b, the extension side circuit 73, and the extension side chamber 52a are communicated with each other via the.

Therefore, in the telescopic cylinder 51, as in the first embodiment, the extension side chamber 52a and the shortening side chamber 52b have the same pressure, and the oil discharged from the shortening side chamber 52b is supplied to the extension side chamber 52a.
As a result, similarly to the first embodiment, the extension driving force of the telescopic cylinder 51 can be suppressed, and the effect 1) and the effect 3) can be obtained.

As described above, the carrier mobile carrier of the second embodiment is
The hydraulic circuit 270 serving as a fluid pressure circuit includes a switching valve 275 capable of communicating and blocking between the shortening side chamber 52b and the expansion side chamber 52a, and the hydraulic pressure supply circuit 71 side (pump P side) and the drain circuit 72 side,
The switching valve 275 communicates the fixed position 75b that seals the shortening side chamber 52b and the extension side chamber 52a and the shortening side chamber 52b to the hydraulic pressure supply circuit 71 side (pump P side), while the extension side chamber 52a is connected to the drain circuit 72 side. A shortening side position 75c that communicates, and an expansion side position 75a that communicates the shortening side chamber 52b to the drain circuit 72 side while communicating the stretching side chamber 52a to the hydraulic pressure supply circuit 71 side (pump P side),
Further, when the switching valve 275 is set to the expansion side position 75a between the switching valve 275 and the expansion / contraction cylinder 51, the hydraulic circuit 270 is connected to the circuit (extension side circuit 73) and the shortening side chamber 52b communicating with the expansion side chamber 52a. It was set as the loading platform mobile transport vehicle provided with the differential valve 200 which connects the circuit (short circuit 74) connected.
Therefore, in the second embodiment, similarly to the first embodiment, the extension driving force of the telescopic cylinder 51 can be suppressed, and the effects 1) and 3) can be obtained. The valve 275 has a general extension side position 75a and a reduction side position 75c that connect the hydraulic pressure supply circuit 71 and the drain circuit 72 to one of the extension side circuit 73 and the shortening side circuit 74, respectively. A switching valve having a structure can be used. Similarly, a switching valve having a general structure can be used as the differential valve 200, which is excellent in versatility.

  As described above, the loading platform mobile vehicle of the present disclosure has been described based on the embodiment. However, the specific configuration is not limited to the embodiment, and the design change or the design can be changed without departing from the gist of the present disclosure. Addition is permitted.

For example, in the embodiment, a vehicle transport vehicle is shown as the load carrier mobile transport vehicle, but the load to be transported is not limited to the vehicle.
In the embodiment, the differential circuit is provided in the switching valve and the differential valve. However, the present invention is not limited to this, and a valve capable of communicating the shortened side chamber and the extended side chamber can be expanded and contracted. You may provide in a cylinder.
Further, in the embodiment, oil is shown as a fluid for driving the forward / rearward movement cylinder, but the fluid is not limited to oil, and other fluids such as liquid other than oil or gas are used. be able to.
Further, any mechanism may be used as the mechanism for moving the cargo bed as long as it uses a cylinder driven by fluid pressure when moving the cargo bed in the longitudinal direction of the vehicle. It is not limited to the thing of a structure.
For example, the mechanism for tilting the tilt frame is not limited to that shown in the embodiment, and a known structure described in Patent Document 1 may be used.
In addition, in the embodiment, when the telescopic cylinder is installed, the piston rod is connected to the tilting frame, and the tube is connected to the loading platform. Conversely, the piston rod is connected to the loading platform, The tube may be connected to a tilting frame.

1 vehicle 3 tilting frame 4 loading platform 11 chassis frame (chassis)
51 Telescopic cylinder (cylinder for back and forth movement)
51a Piston rod 51b Piston 52 Tube 52a Extension side chamber 52b Reduction side chamber 70 Hydraulic circuit (fluid pressure circuit)
71 Hydraulic supply circuit 72 Drain circuit 73 Expansion side circuit 74 Shortening side circuit 75 Switching valve 75a Expansion side position 75b Fixed position 75c Shortening side position 75d Differential circuit 200 Differential valve 200a Shortening side position 200b Expansion side position 270 Hydraulic circuit 275 switching Valve 275d Circuit part (differential circuit)
A Cargo carrier truck G Ground

Claims (4)

A loading platform supported so as to be movable in the longitudinal direction of the vehicle with respect to the vehicle chassis,
A forward / backward movement cylinder interposed between the loading platform and the chassis, moving the loading platform rearward by extension driving, and moving the loading platform forward by shortening driving;
A fluid pressure circuit capable of supplying and discharging fluid pressure to the forward / backward movement cylinder;
A load carrier mobile carriage equipped with
A loading platform moving type in which the fluid pressure circuit is provided with a differential circuit that communicates the shortened side chamber and the stretched side chamber defined by the piston of the forward / backward movement cylinder when the forward / backward movement cylinder is extended. Truck. In the load carrier movable transport vehicle according to claim 1,
The fluid pressure circuit includes a switching valve capable of communicating and blocking between the shortening side chamber and the extension side chamber, the fluid pressure supply source side and the drain side,
The switching valve includes a fixed position in which the shortened side chamber and the extension side chamber are sealed, and a shortened side position in which the shortened side chamber communicates with the fluid pressure supply source side while the extension side chamber communicates with the drain side. And a decompression side position having the differential circuit that communicates the shortening side chamber and the extension side chamber with the fluid pressure supply side. In the load carrier movable transport vehicle according to claim 1,
The fluid pressure circuit includes a switching valve capable of communicating and blocking between the shortening side chamber and the extension side chamber, the fluid pressure supply source side and the drain side,
The switching valve includes a fixed position in which the shortened side chamber and the extension side chamber are sealed, and a shortened side position in which the shortened side chamber communicates with the fluid pressure supply source side while the extension side chamber communicates with the drain side. An extension side position for communicating the shortened side chamber to the drain side, while communicating the extension side chamber to the fluid pressure supply side,
Further, the fluid pressure circuit includes a circuit that communicates with the extension side chamber and the shortening side chamber between the changeover valve and the forward / backward movement cylinder, substantially in conjunction with the changeover valve being set to the extension side position. A load carrier mobile vehicle equipped with a differential valve for connecting a circuit communicating with the vehicle. In the load carrier movable transport vehicle according to any one of claims 1 to 3,
The carrier is supported so as to be movable in the vehicle front-rear direction, and the vehicle rear side end of the carrier is supported so as to be groundable by the extension drive of the cylinder for forward and backward movement.