JPH0618069U - Lorry vehicle controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To smoothly carry out the sliding operation of the loading platform by providing a means for holding the tilt angle of the tilting frame at the predetermined tilt position. [Structure] On a tilting frame whose rear end is pivotally supported on a chassis, a loading platform is slidable in the front-rear direction, and the tilting frame is tilted to a predetermined position by a lift cylinder linked between the chassis and the tilting frame. In a freight vehicle that slides the platform in the front-rear direction while the relay frame is not in the predetermined tilt position, the relay CR1
Of the limit switch LS1 that energizes the b contact of the above and the output of the above limit switch LS1 when the platform is sliding,
When the tilt angle of tilting frame 2 falls below the predetermined tilt position, the high-pressure dump switching valve for dump raising is positioned at the supply position while the low-pressure switching valve for dump lifting is positioned at the discharge position until the tilt frame returns to the predetermined tilt position. As described above, there is provided a second branch path 31a2 of a dump raising drive circuit 31a having a contact b of a relay CR1 for energizing the solenoid SOLa of the dump raising high pressure switching valve and the solenoid of the dump raising low pressure switching valve.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a control device for a lorry, and more particularly to a measure for maintaining a rearward tilted state of a tilting frame.

[0002]

[Prior art]

 Generally, in a freight vehicle, a tilting frame whose rear end is pivotally supported on a chassis so that it can be tilted rearward, a hydraulic cylinder linked between the chassis and the tilting frame, and a tilting frame that slides forward and backward. And a pallet that is movably supported.The hydraulic cylinder is extended to tilt the tilting frame backward to a predetermined position, and then the pallet is slid in the front-rear direction so that the rear end of the pallet with respect to the ground surface. The cargoes can be easily loaded and unloaded by moving them closer to each other. In this case, the loading platform slides in the front-rear direction by the extension / contraction operation of the extension / contraction cylinder linked with the tilting frame.

[0003]

[Problems to be solved by the device]

 However, in the case where the tilting frame is tilted backward by the expansion / contraction motion of the hydraulic cylinder as described above, there is a possibility that the oil pressure in the hydraulic cylinder may decrease due to oil leakage from the packing. The rearward tilt angle at is in an insufficient tilted state, that is, the rearward tilt angle at the predetermined tilt position of the tilting frame decreases (becomes smaller). Therefore, there is a disadvantage that an angle difference is generated between the tilting frame and the bed, and an unreasonable load acts on the tilting frame and the bed, so that the sliding operation of the bed cannot be performed smoothly.

The present invention has been made in view of the above points, and an object thereof is to perform a sliding operation of a loading platform by providing a means for maintaining a backward tilt angle at a predetermined tilt position of a tilt frame. It is to be able to do smoothly.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a solution means taken by the present invention is, as a freight vehicle control device, between a tilting frame having a rear end portion pivotally supported on a chassis so as to be able to tilt backward, and the chassis and the tilting frame. It is equipped with an associated hydraulic cylinder and a loading platform that is slidably supported on the tilting frame in the front-rear direction.The hydraulic cylinder is extended to tilt the tilting frame back to a predetermined position, and then the loading platform is moved back and forth. It is premised on a freight vehicle in which cargo can be loaded and unloaded from a cargo bed by sliding it in the direction. Then, when the tilting frame detects an insufficient tilt state at a predetermined tilt position, an electromagnetic switching valve that is provided in the hydraulic circuit of the hydraulic cylinder and supplies pressure oil to the hydraulic cylinder, and the bed is slid, Control means for receiving the output of the detection means and for controlling the electromagnetic switching valve to be positioned at the supply position until the tilting frame returns to the predetermined tilt position.

[0006]

[Action]

 With the above structure, in the present invention, the control means extends the hydraulic cylinder between the chassis and the tilting frame to tilt the tilting frame rearward to a predetermined position and then slides the loading platform in the front-rear direction. At this time, the electromagnetic switching valve switches to the supply position until the tilt frame returns to the predetermined tilt position by receiving the output from the detection means that detects the state where the rear tilt state of the tilt frame is not at the predetermined tilt position. Since pressure oil is supplied to the positive pressure side oil chamber of the cylinder, even if the hydraulic pressure of the tilting cylinder is reduced due to oil leakage from the packing, etc. Since it is held at the position, it is possible to reliably prevent the occurrence of an angle difference between the tilting frame and the platform that is slid rearward with respect to the tilting frame.

Moreover, the control by the control means for returning the tilting frame to the predetermined tilted position is performed at any time when the loading platform is slid in response to the output from the detection means, so that the loading platform sliding work is performed while the above control is performed. You don't have to wait.

[0008]

[Effect of device]

 As described above, according to the control device for a freight vehicle of the present invention, the rearward tilted state of the tilting frame does not reach the predetermined tilted position during the sliding operation of the carrier after tilting the tilting frame to the predetermined position. When the tilting frame returns to the predetermined tilt position, the control means that supplies pressure oil to the hydraulic cylinder until the tilting frame returns to the predetermined tilting position keeps the tilting frame at the predetermined tilting position regardless of the decrease in the hydraulic pressure of the tilting cylinder, and tilts the frame and the platform. Since the angle difference between them is reliably prevented, it prevents the undesired load between the tilting frame and the loading platform that acts between the tilting frame and the loading platform during the front sliding work in which the loading platform slides from the back to the front, and the loading platform slides. The work can be done smoothly. Moreover, control by the control means for positioning the tilting frame at the predetermined tilt position can be performed at any time during sliding of the loading platform, and the sliding operation of the loading platform can be continued.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a freight vehicle to which a control device according to an embodiment of the present invention is applied. 1 is a chassis of a vehicle V connected to a rear portion of a cabin C, and SC is provided on the chassis 1. The sub chassis 2 is a tilting frame which is pivotally supported at the rear end portion of the sub chassis SC so as to be tiltable (rear tiltable) about a horizontal axis 4, and 3 is slidable in the front-back direction with respect to the tilting frame 2. It is a supported cargo loading platform. The loading platform 3 has a deck surface 3a which is formed to have a width substantially corresponding to the cabin C and extends rearward on the chassis 1, and a frame-shaped front wall 3b which is formed at a height substantially matching the cabin C. The left and right side walls 3c, 3c are formed at a height approximately half the height of the front wall 3b, and the rear wall 3d has a pivot shaft (not shown) at the lower end and is opened and closed rearward.

On the front side of the central portion of the tilting frame 2, a base end shaft 11a is a lift cylinder 11 (only one of which is shown in the figure) as a hydraulic cylinder pivotally supported at a substantially central portion of the sub chassis SC. Is connected at its tip and is rotatably supported around the horizontal shaft 12 at this tip. That is, when the lift cylinder 11 is extended, the tilting frame 2 is in a tilted state (backward tilted state), and when the lift cylinder 11 is shortened, the tilting frame 2 is in a lying state (horizontal state). The tilt angle of the tilting frame 2 (packing platform 3) is set to a maximum tilt angle of about 53 ° so that the sand and the like can be smoothly discharged when loaded as cargo. Further, an extendable telescopic cylinder 13 is linked between the front end portion of the tilting frame 2 and the loading platform 3, and the loading and unloading operation of the telescopic cylinder 13 causes the loading platform 3 to move forward and backward with respect to the tilting frame 2. It is designed to slide. When the platform 3 slides due to the expansion / contraction operation of the expansion / contraction cylinder 13, the tilting frame 2 tilted by the extension operation of the lift cylinder 11 is at a predetermined position, that is, the tilting angle of the tilting frame 2 with respect to the sub-chassis SC is approximately 12 °. The limit switch LS1 provided on the tilting frame 2 detects the tilting angle of the tilting frame 2 at a predetermined tilting position. When loading and unloading cargo onto and from the loading platform 3, the lift cylinder 11 is extended to tilt the loading platform 3 to a predetermined position so that the loading and unloading of cargo can be performed smoothly. By extending 13 and sliding the loading platform 3 rearward with respect to the tilting frame 2, cargo is loaded and unloaded from the rear end of the loading platform 3 that is close to the ground surface. In this case, the rear wall 3d of the loading platform 3 is opened backward (falling down) when cargo is loaded and unloaded, and its rear end (upper end when closed) is grounded to the ground surface. It has the function of a walking board that minimizes the gap between the ground surface and the ground.

Further, at the left and right positions of the rear end portion of the tilting frame 2, there are provided expandable and contractible jacks 14 that extend in a state where the loading platform 3 is slid backward with respect to the tilting frame 2 tilted at a predetermined angle. In addition, when working with the loading platform 3 slid backward, the front wheels float and the rear end of the loading platform 3 protruding from the tilting frame 2 is lowered due to a change in the center of gravity, thereby preventing an unexpected risk.

Next, the hydraulic circuit of each cylinder 11, 13 will be described with reference to FIG.

FIG. 2 shows a piping system of a hydraulic circuit, where P is a hydraulic pump, T is an oil reservoir, 21 is a high-pressure switching valve for dump raising as an electromagnetic switching valve for operating the lift cylinder 11, and 22 is The dump truck high-pressure switching valve 21 has a solenoid SOLa, and the cargo platform switching valve 22 has a solenoid SOLd and a solenoid SOLe. The high-pressure dump switching valve 21 and the bed switching valve 22 are connected in parallel to the hydraulic pump P.

Further, 23 is a low pressure switching valve for raising the dump for circulating the oil in the back pressure side oil chamber 11b of the lift cylinder 11 to the oil reservoir T at the time of expansion, and 24 is the pressure in the positive pressure side oil chamber 11a of the lift cylinder 11. A dump lowering switching valve for circulating oil to the oil reservoir T when the oil is shortened. The dump raising low pressure switching valve 23 has a solenoid SOLb, and the dump lowering switching valve 24 has a solenoid SOLc. ing. Reference numeral 25 is a relief valve for lowering the back pressure of the lift cylinder 11 by causing a part of the oil to circulate while bypassing the low-pressure switching valve 24 for raising the dump cylinder when the back pressure of the lift cylinder 11 rises too much. Then, a part of the oil that circulates after passing the dump lowering switching valve 24 passes through the neutral position of the dump raising low pressure switching valve 23, and is transferred from the oil reservoir T to the back pressure side oil chamber 11b of the lift cylinder 11. It is designed to flow in together with makeup oil. Further, reference numeral 26 is a check valve for preventing pressure oil in the positive pressure side oil chamber 11a of the lift cylinder 11 from flowing back through the high pressure dump switching valve 21. On the other hand, 27 is a sequence valve for operating the pressure oil flowing into the positive pressure side oil chamber 13a of the telescopic cylinder 13 to circulate the oil in the back pressure side oil chamber 13b to the oil reservoir T and extend the telescopic cylinder 13. Reference numeral 28 is a relief valve provided in parallel with the cargo bed switching valve 22. Reference numeral 29 is a filter for removing impurities in the oil circulating from the cylinders 11 and 13 to the oil reservoir T.

Next, the electric circuit will be described with reference to FIG.

In FIG. 3, reference numeral 32 is a power supply line, 33 is a ground line, and a circuit for controlling the operation of each of the cylinders 11 and 13 across the power supply line 32 and the ground line 33. Is provided. In the figure, 30a is a power-on circuit for powering on each circuit so that each cylinder 11 and 13 can be controlled, and the power-on circuit 30a includes an ignition switch provided on a control panel in a driver's seat. A switch Si and a main switch SW1 are connected in series with a pilot lamp PL which is lit so as to indicate an operable state of each cylinder 11, 13 by energizing the ignition switch Si and the main switch SW1.

That is, by energizing the main switch SW1 while the ignition switch Si is energized, the pilot lamp PL is lit up to be in a usable state. After that, the main switch SW1 is energized. As a result, in the traveling state of the vehicle V, the tilting frame 2 is brought into close contact with the chassis 1 so that the tilt angle is 0 °, and the loading platform 3 is fixed to the tilting frame 2.

Reference numeral 30b denotes a predetermined tilt angle detection circuit for detecting that the tilt angle of the tilting frame 2 with respect to the sub-chassis SC is positioned at a predetermined tilt angle of approximately 12 °, and the predetermined tilt angle detection circuit 30b includes The tilting frame 2 is switched to the operating state when the tilting frame 2 is in a predetermined position tilted to a predetermined angle of approximately 12 °, and is switched to the non-operating state when the tilting frame 2 is not at the predetermined tilt angle of approximately 12 °. The limit switch LS1 and the relay CR1 that is energized when the limit switch LS1 is activated are connected in series.

Reference numeral 30c denotes a high tilt angle detection circuit that detects that the tilt angle of the tilt frame 2 with respect to the sub-chassis SC is positioned at a high tilt angle of approximately 53 °. Switches to the operating state when the tilting frame 2 is in the high tilting position tilted to a high tilting angle of approximately 53 °, and switches to the operating stop state when the tilting frame 2 has not yet reached the high tilting angle. A limit switch LS2 and a relay CR2 that is energized when the limit switch LS2 is operated are connected in series.

Reference numeral 30 d denotes a sliding detection circuit for detecting a state where the loading platform 3 is fixed to the tilting frame 2, that is, a state where the loading platform 3 is not sliding. The limit switch LS3, which switches to the operating state when the platform 3 is in the secured state, and switches to the inactive state when the platform 3 is in the sliding state, and energized when the limit switch LS3 is activated. Relay CR3 is connected in series.

Reference numeral 31a denotes a dump raising drive circuit for inclining the tilting frame 2 upward. The dump raising drive circuit 31a is provided with an a contact of the relay CR3 and a dump raising drive provided on the operation panel. Side and dump lowering side switching switch SW2 for dumping up / down (terminal for raising dumping side), the relay CR2 (contact b), the solenoid SOLa of the high pressure switching valve for dumping up 21 or the low pressure switching for dumping up. The solenoid SOLb of the valve 23 (the solenoid SOLa and the solenoid SOLb are connected in parallel) is connected in series. Further, the dump raising / lowering input switch SW2 is provided with an interlocking switch SW2a interlocking with the dumping / lowering input switch SW2. The interlocking switch SW2a (base end side terminal) of the dump lifting / lowering input switch SW2 is connected to the power supply line 32 via the contact b of the relay CR3. A first branch passage 31a1 is provided between the contact a of the relay CR3 of the dump raising drive circuit 31a and the dump raising / lowering input switch SW2. The first branch passage 31a1 is provided on the operation panel. Of the tilt frame raising / lowering switch SW3a and a base end of the interlocking switch SW3a interlocking with the tilt frame raising / lowering switch SW3. They are connected in parallel with the child respectively. The base end side terminal of the interlock switch SW2a is connected to the power supply line 32.

Reference numeral 31b denotes a dump lowering drive circuit for inclining the tilting frame 2 downward. The dump lowering drive circuit 31b includes the dump raising / lowering input switch SW2 (dump lowering terminal) and the tilting. Each of them is connected in parallel to a frame elevating closing switch SW3 (tilt frame lowering terminal).

Reference numeral 31c denotes an accelerator acceleration drive circuit for increasing the speed of an accelerator (not shown) of the engine. The accelerator acceleration drive circuit 31c is connected via an accelerator acceleration solenoid SOLr. It is connected to the interlocking switch SW3a (tilt frame raising side terminal) of the tilt frame raising / lowering input switch SW3. The accelerator acceleration drive circuit 31c is provided with first and second branch paths 31c1 and 31c2, respectively. The first branch path 31c1 has its proximal end terminal connected to the power supply line 32. In addition, the loading platform low-tilt rear sliding side and the loading platform low-tilt front sliding side of the operation panel can be switched to the loading platform low-tilt sliding input switch SW4 of the loading platform low-tilting rear sliding side terminal and the loading platform low-tilting front sliding side. Connected in parallel to the terminals. On the other hand, the second branch path 31c2 is connected to the base end side terminal of the interlocking switch SW4a which is interlocked with the loading switch SW4 for low inclination sliding of the bed through the a contact of the relay CR1.

Reference numeral 31 d denotes a rear loading platform driving circuit for sliding the loading platform 3 rearward. The rear loading platform driving circuit 31 d is configured to lower the loading platform via the solenoid SOL d of the loading platform switching valve 22. It is connected to the interlocking switch SW4a (terminal for low slant rear sliding side of loading platform) of the closing switch SW4 for slant sliding.

Reference numeral 31e denotes a loading platform front sliding drive circuit for sliding the loading platform 3 forward. The loading platform front sliding driving circuit 31e is configured to lower the loading platform via the solenoid SOL e of the loading platform switching valve 22. It is connected to the interlocking switch SW4a (the loading platform low-tilt front sliding-side terminal) of the tilt-sliding closing switch SW4. Further, the drive circuit 31e for sliding the front of the loading platform is provided with a branch passage 31e1. The branch passage 31e1 is connected to the dump up-side terminal and the dump down-side terminal of the interlocking switch SW2a of the dump up / down closing switch SW2. It is connected in parallel.

As a characteristic part of the present invention, a second branch path 31a2 is provided between the dump rising side terminal of the dump raising / lowering input switch SW2 of the dump raising drive circuit 31a and the relay CR2. The second branch path 31a2 is connected to the second branch path 31c2 (the anti-interlocking switch SW4a side closer than the a contact of the relay CR) of the accelerator acceleration drive circuit 31c via the b contact of the relay CR1. Each of them is connected in parallel to the dump lifting terminal of the dump lifting closing switch SW2 via the b contact of CR1. In that case, the contact b of the relay CR1 in the second branch path 31a2 of the drive circuit 31a for dump lift is de-energized by the limit switch LS1 which is switched to the operating state when the tilting frame 2 is in the fixed position tilted to the predetermined angle. The state, that is, the energization state occurs when the tilting frame 2 is not in the predetermined tilted position. Therefore, the limit switch LS1 (the contact b of the relay CR1) detects the tilting frame 2 not in the predetermined tilted state. Are configured.

Here, the tilting operation and the sliding operation of the platform 3 performed after the traveling is stopped will be described in order.

First, the case where the loading platform 3 is tilted to a high tilt angle will be described. When the ignition switch Si is energized, the main switch SW1 is energized so that the pilot lamp PL is turned on to be ready for use. In this usable state, the respective limit switches LS1 and LS2 are switched to the non-operating state and the LS3 is switched to the operating state, the relays CR1 and CR2 are in the non-conductive state, and the CR3 is in the conductive state. Therefore, when the dump raising / lowering closing switch SW2 is switched (closed) to the dump rising side, the dump raising operation is performed through the contact a of the relay CR3, the dump rising side terminal of the dump lifting closing switch SW2, and the contact b of the relay CR2. By energizing the solenoid SOLa of the high pressure switching valve 21, the dump raising high pressure switching valve 21 is switched to the left position which is the supply position, and the solenoid SOLb of the dump raising low pressure switching valve 23 is excited to lower the dump raising low pressure. The switching valve 23 is switched to the right position, which is the discharge position. Even when the tilting frame raising / lowering closing switch SW3 is switched to the tilting frame raising side (upper side in FIG. 3), the dumping raising high-pressure switching valve is similarly operated through the b contact of the relay CR1 and the b contact of the relay CR2. 21 is switched to the left position, and the dump raising low-pressure switching valve 23 is switched to the right position. Therefore, the pressure oil from the hydraulic pump P flows into the positive pressure side oil chamber 11a of the lift cylinder 11 through the high pressure dump switching high pressure switching valve 21, and the oil in the back pressure side oil chamber 11b of the lift cylinder 11 rises to the dump. It circulates to the oil reservoir T through the low pressure switching valve 23 for use, and the piston rod of the lift cylinder 11 extends to tilt the tilting frame 2. In this case, when the dump raising / lowering closing switch SW2 is switched to the dump rising side, the interlocking switch SW2a of the dump lifting / lowering closing switch SW2 is also switched to the dump rising side, but the contact b of the relay CR3 before that is in the non-energized state. Therefore, even if the interlock switch SW2a is switched, there is no effect on the operation. On the other hand, when the interlocking switch SW3a of the tilting frame lifting closing switch SW3 is switched by switching to the tilting frame raising side by the tilting frame lifting closing switch SW3, the solenoid SOLr is excited to accelerate the accelerator and the hydraulic pump. The power supply to P will not be in short supply. Further, when the oil pressure in the back pressure side oil chamber 11b of the lift cylinder 11 rises excessively, the relief valve 25 operates to bypass a part of the oil in the back pressure side oil chamber 11b of the lift cylinder 11 to the dump raising low pressure switching valve 23. By circulating the oil to the oil reservoir T, the hydraulic pressure in the back pressure side oil chamber 11b of the lift cylinder 11 is lowered.

When the tilting frame 2 is tilted to a high tilting angle, the tilting angle of the tilting frame 2 at the high tilting position is detected by the limit switch LS2 and the relay CR2 is turned on. For this reason, the contact b of the relay CR2 of the dump rise drive circuit 31a is separated so that both the solenoid SOLa of the dump rise high-pressure switching valve 21 and the solenoid SOLb of the dump rise low-pressure switching valve 23 are prohibited (non-energized). Causes the high-pressure dump switching valve 21 to switch to the right position (neutral position) and the low-pressure dump switching valve 23 to switch to the left position (neutral position) to stop the expansion and contraction operation of the lift cylinder 11. The tilting of the tilting frame 2 is stopped. In this case, pressure oil in the positive pressure side oil chamber 11a of the lift cylinder 11 is locked by the check valve 26 and is prevented from circulating, and the tilting frame 2 is fixed at a high tilt angle.

Then, in order to return the tilt of the tilting frame 2, the dump raising / lowering closing switch SW2 is switched to the dump lowering side (lower side in FIG. 3), or the tilting frame raising / lowering switch SW3 is set to the tilting frame lowering side ( 3), the solenoid SOLc of the dump lowering switching valve 24 is excited to switch the dump lowering switching valve 24 to the right position (discharging position). As a result, the oil in the positive pressure side oil chamber 11a of the lift cylinder 11 can be recirculated to the oil reservoir T via the dump lowering switching valve 24, and the oil that recirculates after passing through the dump lowering switching valve 24 can be recirculated. A part of the branch is made to pass through the neutral position of the dump rise low-pressure switching valve 23 and can flow into the back pressure side oil chamber 11b of the lift cylinder 11 together with the makeup oil from the oil reservoir T. Therefore, the weight of the tilting frame 2 on which the loading platform 3 is placed acts to shorten the lift cylinder 11, and the tilting angle of the tilting frame 2 starts to decrease, so that the limit switch LS2 stops operating and the relay CR2 operates. It becomes non-energized. The tilting of the tilting frame 2 is continued until the tilting angle becomes 0 degree.

In this case, when the dump raising / lowering input switch SW2 is switched to the dump rising side or the dump lowering side, even if the securing of the loading platform 3 to the tilting frame 2 is released, the limit switch LS3 is used. When the loading platform 3 is detected to be in the sliding state, the limit switch LS3 is deactivated, and the contact point b of the relay CR3 is switched to the solenoid SOLe of the loading platform switching valve 22 through the interlocking switch SW2a of the dump raising / lowering closing switch SW2. The power is turned on, and the cargo bed switching valve 22 is switched to the lower position. Therefore, the pressure oil flows into the exhaust pressure side oil chamber of the telescopic cylinder 13, while the pressure oil in the positive pressure side oil chamber 13a of the telescopic cylinder 13 circulates to the oil reservoir T, and the piston rod of the telescopic cylinder 13 is shortened. Then, the loading platform 3 is slid forward with respect to the tilting frame 2. Then, the loading platform 3 contacts the stopper of the tilting frame 2 and is hydraulically locked and fixed.

Next, a description will be given of the case where the loading platform 3 is slid backward to a predetermined tilt angle. When the ignition switch Si is energized, the main switch SW1 is energized to turn on the pilot lamp PL. After the state of being ready for use, the loading switch SW4 for low-tilt sliding of the platform can be switched to the rear-tilting side of the platform with low inclination (upper side in FIG. 3). Then, the solenoid SOLr is excited to accelerate the accelerator, and at the same time, the contact point of the relay CR1 and the contact point of the relay CR2 of the dump rising drive circuit 31a in the second branch path 31a2 of the dump rising drive circuit 31a are increased. The solenoid SOLa of the high-pressure dump switching valve 21 and the solenoid SOLb of the low-pressure dump switching valve 23 are both excited so that the high-pressure dump switching valve 21 is in the left position and the low-pressure dump switching valve 23 is in the right position. Switch to each position. Therefore, the oil in the positive pressure side oil chamber 11a and the back pressure side oil chamber 11b of the lift cylinder 11 flows in the same manner as when the cargo bed 3 is tilted to a high tilt angle, and the piston rod of the lift cylinder 11 is extended to tilt the tilt frame. Tilt 2

When the tilting frame 2 is tilted to a predetermined angle, the limit switch LS1 detects the tilting state of the tilting frame 2 at a predetermined position, and the relay CR1 is energized. Therefore, the contact b of the relay CR1 in the second branch path 31a2 of the dump raising drive circuit 31a is separated to excite the solenoid SOLa of the dump raising high pressure switching valve 21 and the solenoid SOLb of the dump raising low pressure switching valve 23. By prohibiting both of them, the high-pressure dump switching valve 21 is switched to the right position, and the low-pressure dump switching valve 23 is switched to the left position, so that the expansion and contraction operation of the lift cylinder 11 is stopped and the tilting frame 2 is stopped. Stop tilting. In this case, pressure oil in the positive pressure side oil chamber 11a of the lift cylinder 11 is locked by the check valve 26 and is prevented from circulating, and the tilting frame 2 is fixed at a predetermined tilt angle.

On the other hand, through the contact a of the relay CR1 in the second branch path 31c2 of the accelerator acceleration drive circuit 31c, the interlocking of the loading switch SW4 for loading low inclination of the loading platform that is switched to the backward sliding side of the loading platform low inclination. The switch SW4a energizes the solenoid SOLd of the cargo bed switching valve 22 to switch the cargo bed switching valve 22 to the upper position. Therefore, the pressure oil flows into the positive pressure side oil chamber 13a of the telescopic cylinder 13, the sequence valve 27 is actuated by this pressure oil, and the oil in the back pressure side oil chamber 13b of the telescopic cylinder 13 is transferred to the oil reservoir T. Circulating, extending the piston rod of the telescopic cylinder 13, and sliding the loading platform 3 rearward with respect to the tilting frame 2. Then, when the rear end of the loading platform 3 reaches the vicinity of the ground, the telescopic cylinder 13 is in the maximum extension state and the rearward sliding is completed. In this state, a walk board is passed between the rear end of the loading platform 3 and the ground to load and unload cargo. It is possible to slide the loading platform 3 to the rear up to the maximum stroke of the telescopic cylinder 13. However, when it is desired to stop the loading platform 3 during the sliding, the loading switch SW4 for loading the low tilting loading platform can be moved to the neutral position (see the figure). Position).

Next, when the loading platform 3 is slid forward, the loading platform low tilt sliding closing switch SW4 is switched to the loading platform low tilt front sliding side (lower side in FIG. 3). Then, the solenoid SO Lr is excited to accelerate the accelerator, and the solenoid of the cargo bed switching valve 22 is passed through the a contact of the relay CR1 and the interlocking switch SW4a in the second branch path 31c2 of the accelerator acceleration drive circuit 31c. The SOLe is energized, and the cargo bed switching valve 22 is switched to the lower position. Therefore, the pressure oil flows into the discharge-side oil chamber of the telescopic cylinder 13, while the pressure oil in the positive-pressure side oil chamber 13a of the telescopic cylinder 13 circulates to the oil reservoir T, shortening the piston rod of the telescopic cylinder 13. Then, the loading platform 3 is slid forward with respect to the tilting frame 2. Then, the loading platform 3 contacts the stopper of the tilting frame 2 and is hydraulically locked and fixed.

In this case, when the tilting frame 2 is no longer in the predetermined tilted state, that is, when the predetermined tilting angle of the tilting frame 2 is lowered while the loading platform 3 is sliding, the second branch of the dump lifting drive circuit 31a is performed as described above. It is detected by the limit switch LS1 that energizes the contact b of the relay CR1 in the path 31a2, and is connected to the contact b of the relay CR1 in the second branch path 31a2 of the drive circuit 31a for lifting the dump, and the solenoid solenoid SOLa of the high pressure switching valve for dump lifting 21a. Also, the excitation of the solenoid SOLb of the low-pressure dump switching valve 23 is restarted together, and the lift cylinder 11 is extended by supplying / discharging oil to / from the lift cylinder 11 until the tilting frame 2 returns to the predetermined tilt angle. Therefore, the second branch path 31a2 of the dump lifting drive circuit 31a having the b-contact of the relay CR1 is used. Thus, when the load platform 3 slides, the output of the limit switch LS1 is received, and the high-pressure switching valve 21 for dump rise is positioned at the supply position until the tilt frame 2 returns to the predetermined tilt position. It constitutes a control means for controlling the low pressure switching valve 23 to be positioned at the discharge position.

The operation for returning the tilt of the tilting frame 2 is the same as when the loading platform 3 is returned from the high tilt angle, and the tilting frame elevating closing switch SW3 is set to the tilting frame descending side or the tilting frame elevating closing switch. This can be achieved by switching SW3 to the lower side of the tilting frame. The lift cylinder 11 is shortened by the weight of the tilting frame 2 on which the loading platform 3 is placed, and the tilting angle of the tilting frame 2 is continued until it reaches 0 degrees. To do.

Therefore, in the above embodiment, the cylinder rod of the lift cylinder 11 is extended between the chassis 1 and the tilting frame 2 by the b contact of the relay CR1 in the second branch path 31a2 of the dump lift drive circuit 31a. By doing so, when the tilting frame 2 is not tilted to the predetermined tilt position and the loading platform 3 is slid in the front-rear direction, when the tilting frame 2 is not in the predetermined tilt position, the contact b of the relay CR1 is energized. When the output from the limit switch LS1 is received and the tilting frame 2 returns to the predetermined tilt position when the tilting angle of the tilting frame 2 falls below the predetermined tilt position, the high-pressure dump switching valve 21 for raising the dump is supplied to the supply position. To supply the pressure oil to the positive pressure side oil chamber 11a of the lift cylinder 11, while the low pressure switching valve 23 for raising the dump is positioned at the discharge position. By circulating the oil in the pressure side oil chamber 11b, the lift cylinder 11 is extended and the tilting frame 2 is returned to a predetermined tilted position, so that the hydraulic pressure of the lift cylinder 11 is lowered due to oil leakage from the packing. Also, the rearward tilt angle of the tilting frame 2 at the predetermined tilting position is maintained at the predetermined tilting position without lowering, and the tilting frame 2 and the loading platform 3 slid backward with respect to the tilting frame 2. It is possible to surely prevent an angle difference from occurring. As a result, it is possible to prevent an undesired load from being generated due to an angle difference that acts between the tilting frame 2 and the bed 3 during the front sliding work in which the bed 3 is slid from the rear side to the front side. The operation work can be smoothly performed.

Further, the control by the contact b of the relay CR1 in the second branch path 31a2 of the dump raising drive circuit 31a for positioning the tilting frame 2 at the predetermined tilt position is performed by setting the loading platform low inclination sliding loading switch SW4 to the loading platform low inclination rear. If it is in the state of switching to the sliding side or the loading platform low-tilt forward sliding side, the output from the limit switch LS1 will be received at any time when the loading platform slides. Therefore, for the loading platform low-tilting sliding while the above control is performed. It is not necessary to switch the closing switch SW4 to the neutral position to wait for the sliding operation of the loading platform 3 and the sliding operation of the loading platform 3 can be continued.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but includes various other modified examples. For example, in the above embodiment, the control in the case where the tilting frame 2 is tilted with respect to the chassis 1 and the loading platform 3 is slid with respect to the tilting frame 2 is described, but the loading platform is tilted with respect to the tilting frame tilted at a predetermined tilt angle. In order to prevent the unexpected risk that the front wheels will float and the rear end of the loading platform protruding from the tilting frame will fall due to fluctuations in the center of gravity during work with the rear part slid backward, the control to extend and retract the jack is in the electrical circuit. Of course, it may be included in the.

In the above embodiment, the tilting angle of the tilting frame 2 with respect to the chassis 1 is tilted to about 53 °, but the tilting angle of the tilting frame with respect to the chassis is only about 12 °. It may be applied to a dedicated vehicle.

Further, in the above embodiment, the tilting of the tilting frame 2 with respect to the chassis 1 and the sliding of the loading platform 3 with respect to the tilting frame 2 are performed by the switches SW1 to SW4 provided on the operation panel of the driver's seat. However, among the switches, the tilt frame elevating closing switch SW3 and its interlocking switch SW3a for exciting the solenoid SOLr to accelerate the accelerator, and the loading platform low tilt sliding closing switch SW4 and its interlocking switch SW4a are provided from outside the vehicle. The remote control panel may be provided so that it can be operated remotely from outside the vehicle.

[Brief description of drawings]

FIG. 1 is a side view showing a state in which a truck is partially cut away.

FIG. 2 is a hydraulic circuit diagram of a lift cylinder and a telescopic cylinder.

FIG. 3 is an electric circuit diagram according to FIG.

[Explanation of symbols]

1 chassis 2 tilting frame 3 loading platform 11 lift cylinder (hydraulic cylinder) 21 high-pressure switching valve for dump lifting (electromagnetic switching valve) LS1 limit switch (detection means) 31a2 second branch path of dump-driving drive circuit having b contact of relay (Control means)

Claims (1)

[Scope of utility model registration request] 1. A tilting frame having a rear end pivotally supported on a chassis so as to be able to tilt backward, a hydraulic cylinder linked between the chassis and the tilting frame, and slidable in the front-back direction on the tilting frame. With a supported loading platform, the hydraulic cylinder is extended to tilt the tilting frame backward to a predetermined position, and then the loading platform is slid forward and backward so that cargo is loaded and unloaded on the loading platform. In the freight vehicle, a detecting means for detecting an insufficient tilt state at a predetermined tilt position of the tilting frame, an electromagnetic switching valve provided in the hydraulic circuit of the hydraulic cylinder for supplying pressure oil to the hydraulic cylinder, and a slide for the cargo bed. When the vehicle is moving, it is provided with a control means that receives the output of the detection means and controls the electromagnetic switching valve to be positioned at the supply position until the tilting frame returns to the predetermined tilted position. Control Apparatus.