JPH0319445Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a suspension spring for a wheel in which the hydraulic cylinder piston rod side oil chamber interposed between the vehicle frame and the wheel is connected to a hydraulic power source via a switching valve. This invention relates to a suspension spring locking device capable of locking a suspension spring.

[Prior art] In order to be able to lift a load without using the on-tires of a crane vehicle, that is, the outriggers that protrude to secure the vehicle body, an oil chamber and a hydraulic power source on the piston rod side of a hydraulic cylinder are installed between the vehicle frame and the wheels. A suspension spring locking device that can lock the suspension spring of a wheel by connecting the same is known, for example, as disclosed in Japanese Utility Model Publication No. 57-36492.

Power steering devices that power assist steering force are also known.

Furthermore, as shown in FIG. 2, a system is also known in which the operating section B of the power steering device is connected to the hydraulic pressure source P via the switching valve 1 of the suspension spring lock device. In this system, the switching valve 1 normally connects the actuating part B of the power steering device and the hydraulic pressure source P, but when the suspension spring lock switch 2 is closed, the switching valve driving solenoid 3 is actuated to operate the switching valve 1. The operating part A of the suspension spring locking device is connected to the hydraulic power source P to lock the suspension spring.

With this structure, when the suspension spring lock switch 2 is closed while the vehicle is running, the switching valve driving solenoid 3 is activated to switch the switching valve 1, and the operating part A of the suspension spring locking device and the hydraulic power source P are activated.
The connection between the operating part B of the power steering device and the hydraulic power source P is cut off. Therefore, there is a problem in that the steering force is no longer power assisted and the steering wheel becomes heavy.

[Problems to be Solved] Accordingly, an object of the present invention is to provide a suspension spring lock device that can effectively utilize the hydraulic power source for driving a power steering device and also allows cargo handling to be carried out safely and reliably.

[Means for Solving the Problem] According to the present invention, the oil chamber on the piston rod side of the hydraulic cylinder interposed between the vehicle frame and the wheel is connected to the hydraulic power source of the power steering device via the switching valve to suspend the wheel. In the suspension spring locking device capable of locking the suspension spring, the switching valve is configured to connect the hydraulic pressure source to the piston rod side oil chamber of the hydraulic cylinder when the transmission is in neutral state in the drive circuit of the switching valve. A pilot check valve is provided in the oil chamber on the piston rod side of the hydraulic cylinder to prevent oil from flowing out from the oil chamber, and a pilot pressure introduction pipe for the pilot check valve is provided separately. is selectively switched to the hydraulic source or tank through a switching valve, and the other switching valve is switched on when the suspension spring release switch is on.
The pressure oil from the hydraulic power source is guided to the pilot pressure introduction pipe.

[Description of the function and effect of the invention] Therefore, since the transmission is not neutral while the vehicle is running, the switching valve applies a hydraulic pressure source to the power steering device. For example, when the vehicle is stopped for cargo handling work, the transmission is in neutral, so the switching valve is switched and the pressure oil from the pressure oil source locks the suspension spring. Therefore, the work can be done safely and reliably. For example, if you want to move a certain distance while lifting a load, you will move the transmission to a position other than neutral, so the switching valve will be switched to the power steering device, but since there is a pilot check valve, the oil chamber on the piston rod side will The oil won't come out. The suspension spring is therefore kept locked and can be moved slightly. Then, when carrying out cargo handling work again, pressure oil is applied again.Also, even if the steering wheel is operated during a slight movement, pressure oil is applied to the power steering device, so that the steering wheel operation does not become heavy. When the suspension spring lock release switch is turned on after the cargo handling operation is completed, another switching valve is switched, the pilot check valve is opened, and as a result, the suspension spring is unlocked.

As described above, according to the present invention, cargo handling operations can be carried out safely and reliably, and the vehicle can be moved a short distance with the suspension springs locked. Therefore, the workability of cargo handling work can be improved.

[Preferred Embodiment] When carrying out the present invention, it is preferable that the neutral detection means is constituted by a neutral detection switch that is closed when the transmission is in neutral.

[Example] An example of the present invention will be described below with reference to FIG.

In FIG. 1, hydraulic cylinders 10, 10' for the front wheels and hydraulic cylinders 11, 11' for the rear wheels are interposed between the vehicle frame and the wheels. These hydraulic cylinders 10, 10' and 11, 11' have their respective bottom ends pivotally connected to the vehicle frame, cylinder bodies 12 and 13, and are slidably inserted into the cylinder bodies 12, 13 in an oil-tight manner. Room 1
4, 15 and non-piston side chambers 16, 17, and piston rods 20, 21 whose base ends are connected to the pistons and whose tips are pivoted to the front and rear shafts. The piston rod side oil chambers 14 and 15 of these hydraulic cylinders 10, 10' and 11, 11' are connected to a switching valve 23 by a pipe 24 via a pilot check valve 22, respectively.
3, it is possible to selectively connect to a tank 27 or a hydraulic source, that is, a pump 28. The pilot check valve 22 allows hydraulic oil to flow from the piston rod side oil chambers 14, 15 toward the switching valve 23 when pilot pressure is applied through its pilot pressure introduction pipe 29. . Each pilot pressure introduction pipe 29
is connected to a single switching valve 30, and can be selectively connected to a tank 31 or a pump 32 by operating the switching valve 30. Also, hydraulic cylinders 10, 10', 11, 1
The non-piston rod side chambers 16 and 17 of 1' are each opened to the atmosphere.

The switching valve 23 is connected to the actuating part B of the power steering device by a pipe L, and when the switching valve 23 is operated, the pressure oil of the pump 28 is transferred to the actuating part A of the suspension spring lock device, that is, the piston rod side oil chamber 14 of the hydraulic cylinder. 15 or selectively to the operating section B of the power steering device. The switching valve drive solenoids 33 and 34 of the switching valves 23 and 30 are connected in parallel to a power source 38 via a switching valve drive circuit 35, and the circuit 35 includes a neutral detection switch 36 as a neutral detection means and a suspension A spring lock switch 37 is interposed. This neutral detection switch 36 is normally open and is designed to detect neutral and close only when the transmission is in neutral. Note that 39 is a suspension spring lock release switch.Next, the operation will be explained.

When the vehicle is running, the neutral detection switch 36
The suspension spring lock switch 37 is open, the switching valve drive solenoids 33 and 34 are not operated, and the switching valves 23 and 30 are connected in parallel as shown. Therefore, pump 2
The pressure No. 8 is led to the operating part B of the power steering device, and the power assist of the steering force is performed. Also, the pressure oil of the pump 32 is supplied to the pilot check valve 22.
At the same time, the piston rod side oil chambers 14 and 15 are communicated with the tank 27. Therefore the piston 18,1
9 follows the axle and restricts the vertical movement of the axle so as not to impede the elasticity of the suspension spring. In this case, even if the suspension spring lock switch 37 is closed, the transmission is not in the neutral position, so the neutral detection switch 36 is opened and the switching valve drive circuit 35 is open, and the switching valve drive solenoids 33 and 3 are opened.
4 does not operate to switch the switching valves 23 and 30. Therefore, it is possible to reliably prevent the steering wheel from becoming heavy due to the power assist of the steering force being cut off while the vehicle is running.

When lifting a load on the tires, close the suspension spring lock switch 37 when the vehicle is stopped. At this time, the transmission is in the neutral position and the neutral detection switch 36 is closed, so the changeover valve driving solenoids 33 and 34 are operated to switch the changeover valves 23 and 30 to the cross connection. Then, the pilot pressure introduction pipe 29 connects to the tank 3.
1, thereby communicating with the piston rod side oil chamber 1.
4 and 15, and communicates the piping 24 with the pump 28, thereby transferring the pressure oil of the pump 28 to the piston rod side oil chamber 1.
4, 15, each hydraulic cylinder 10, 10',
11, 11' are reduced to lock the suspension spring.

Furthermore, the present invention is provided with a solenoid circuit shown by a dashed line in FIG. 1, and this solenoid circuit includes a suspension spring lock release switch 39.
is provided. As shown, the switching valve 30
Since this is operated by the solenoids 34 and 34a, the switching valve will not return to the illustrated position once the solenoid 34 is operated unless the switch 39 is turned on. For this reason, for example, when attempting to move a certain distance with a lifted load, the switching valve 23 supplies pressurized oil to the power steering device B as described above, so on-tire suspended traveling is possible without impairing operating force. At that time, the switch 39 remains off, so the solenoid 34a does not operate, so pressure oil is not applied from the pump 32 to each pilot pressure introduction pipe 29, and the pilot check valve 22 is not activated. Since the oil in the piston rod side oil chamber 14 is not released, the suspension spring remains locked. Therefore, movement over a certain distance can be performed stably.

When the suspension spring lock release switch is turned on after the cargo handling operation is completed, the pressure oil from the pump 32 is applied to each pilot check valve 22 and the pressure oil in each piston rod side oil chamber 14 is released, so that the suspension spring lock release switch is turned on. The lock will be released and you can drive normally.

[Effects of the invention] As described above, the invention provides the following excellent effects.

(a) When the transmission is in neutral, the suspension spring is locked, so work is safe and secure.

(b) Since it is possible to travel a short distance with the suspension spring locked, work efficiency is improved.

(c) While the vehicle is running, the hydraulic power source is used for power steering, and the hydraulic power source is used for the spring lock, so there is no waste, and the steering wheel does not become heavy to operate while the vehicle is running.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is an explanatory diagram showing a conventional device. 10, 10', 11, 11'...hydraulic cylinder,
14, 15... Piston rod side oil chamber, 23...
Switching valve, 28...Pump, 35...Switching valve drive circuit, 36...Neutral detection switch.

Claims (1)

[Scope of utility model registration request] A suspension spring locking device that connects a piston rod side oil chamber of a hydraulic cylinder interposed between a vehicle frame and a wheel to a hydraulic power source of a power steering device via a switching valve to lock a suspension spring that suspends the wheel. wherein the switching valve drive circuit is provided with a neutral detection means that enables the switching valve to connect the hydraulic pressure source and the piston rod side oil chamber of the hydraulic cylinder when the transmission is detected as being in neutral; A pilot check valve is provided in the oil chamber on the piston rod side of the piston rod to prevent the oil from flowing out from the oil chamber, and the pilot pressure introduction pipe of the pilot check valve is connected to the hydraulic pressure source or tank via another switching valve. 1. A suspension spring lock device, wherein the other switching valve is configured to guide pressure oil from a hydraulic source to a pilot pressure introduction pipe when a suspension spring lock release switch is on.