JP3691204B2 - Vehicle cab suspension device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cab suspension device for a vehicle.
[0002]
[Prior art]
2. Description of the Related Art A cab suspension for a vehicle is known in which a cab is supported on an air spring using a frame (public technical report No. 95-11883 issued by the Invention Association). In FIG. 2, one sub-tank 4 is provided for each air spring 5, and each of these sub-tanks 4 is connected to the air spring 5 via an electromagnetic valve 3. In this case, a load sensor 1 is provided as means for detecting the load amount of the vehicle, and based on this detection signal, the controller 2 controls the electromagnetic valve 3 to be closed when the vehicle is loaded and opened when the vehicle is empty.
[0003]
When the solenoid valve 3 is opened, the spring constant of the air spring 5 is reduced, and when the solenoid valve 3 is closed, the spring constant of the air spring 5 is increased. Since the spring constant of the air spring 5 alone is matched based on the time of loading, controlling the solenoid valve 3 as described above on the premise of this makes it possible to secure good riding comfort when empty. . A shock absorber 7 is interposed between the cab and the frame, and the damping force thereof can be adjusted via the variable mechanism 6 by manual switching.
[0004]
[Problems to be solved by the invention]
In such a cab suspension, if the spring constant of the air spring and the damping force of the shock absorber are set small to increase the soft riding comfort, the front part of the cab sinks due to the inertial force forward during braking. There was a problem that the so-called nose dive became large. In addition, the swing back after the nose dive is likely to cause bottoming and may cause a large shock. In the case of FIG. 2, the spring constant of the air spring 5 is switched between when the vehicle is empty and when it is loaded, and nose dives and their swinging back during braking cannot be properly suppressed.
[0005]
An object of the present invention is to solve such problems.
[0006]
[Means for Solving the Problems]
In the first invention, an air pulling that supports the front portion of the cab, an air spring that supports the rear portion of the cab, a leveling valve that is interposed in a passage connecting the air spring and the reservoir tank in the front portion of the cab, and the cab Leveling valves installed in a passage connecting the rear air spring and the reservoir tank, and each leveling valve for supplying and exhausting air on the air spring side in order to maintain the cab height in a constant horizontal state In a cab suspension device for a vehicle , comprising a sensing mechanism that independently switches the first solenoid valve of a normally open type that is interposed in each of the passages connecting the sub-tanks for each air spring , and the air at the rear of the cab Normally closed type installed in the passage connecting the cylinder and reservoir tank in parallel with the leveling valve The second solenoid valve and the means for closing the excitation circuit of the first solenoid valve and shutting off the supply / exhaust of each leveling valve and the air spring at the front part of the cab or the rear part of the cab exceed a predetermined value when the brake operates. Means for closing the exciting circuit of the second electromagnetic valve during the stroke is provided.
[0007]
In 2nd invention, the aperture | diaphragm | work which acts on the air which passes 2nd solenoid valve in 1st invention is provided.
[0010]
In a normal state, the air cylinder at the front part of the cab and the air spring at the rear part of the cab are communicated with the sub tank via the normally open type first electromagnetic valve, and softly support the cab with a small spring constant. Because the second solenoid valve is a normally closed type, the leveling valve for the air spring at the rear of the cab also functions to maintain the cab height in a constant horizontal state by supplying and exhausting air on the air spring side. To do. During braking, the excitation circuit of the first solenoid valve is closed and the air supply and exhaust of each leveling valve is shut off, so the air spring at the front of the cab and the air spring at the rear of the cab are in a sealed state with a large spring constant, Sinking of the front part of the cab (nose dive) based on the inertial force forward due to the operation of the brake is suppressed .
[0011]
When the front part of the cab sinks due to the operation of the brake, the rear part of the cab is pushed upward accordingly. The air spring at the rear of the cab swells in a sealed state at the beginning. However, if the air spring at the front of the cab or the air spring at the rear of the cab strokes above a predetermined value, the excitation circuit of the second solenoid valve is closed. Air is supplied from the air reservoir to the air spring at the rear of the cab via the valve. For this reason, the air spring at the rear of the cab is subjected to shaking back after nose dive in a state where the internal pressure is high. In the process of being compressed while pushing out air, the second solenoid valve blocks the passage to the air reservoir, so that the swaying back of the cab is weakened and the bottom does not occur.
[0012]
When the brake is released, it returns to the normal state. The air cylinder at the front of the cab and the air spring at the rear of the cab are communicated with the sub tank via a normally open type first solenoid valve, and the leveling valve supplies and exhausts air from the air spring, so that the cab height is constant. It is returned to the horizontal state. Therefore, the nose dive and the swinging back during braking can be kept small, and the spring constant of the air spring can be set small in order to enhance the soft riding comfort of the cab .
[0013]
In the second invention, at the time of return swing after nose dive, until the second solenoid valve to shut off the passage to the air reservoir, to work the diaphragm air is pushed out from the cab rear air springs to air reservoir, shaking The return momentum can be effectively attenuated.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the figure, 10a to 10d are shock absorbers that support the front, rear, left and right of the cab, 11a and 11b are air springs that support the front left and right of the cab, and 11c and 11d are air springs that similarly support the rear left and right. Sub tanks 13 a to 13 d are provided for each of the air springs 11 a to 11 d, and these sub tanks 13 a to 13 d are connected to the corresponding air springs 11 a to 11 d via a pipe 30. The first solenoid valves 12 a to 12 d are interposed in the middle of each pipe 30. The first solenoid valves 12a to 12d communicate with the passage when the energization to the solenoid 21 is off, and block the passage when the passage to the solenoid 21 is turned on.
[0015]
The air springs 11 a to 11 d are connected to the air reservoir 16 through a pipe 31 with a pair of left and right divided into front and rear. Leveling velves 14 a and 14 b are interposed at the joining portions of the pipes 31. The leveling valves 14a and 14b supply and exhaust air on the air springs 11a to 11d side so as to maintain the cab height in a constant horizontal state. The leveling valves 14a and 14b are leveled as the cab moves up and down with the frame. A sensing mechanism 15 that switches the valves 14a and 14b mechanically is provided.
[0016]
A solenoid 22 for temporarily stopping the leveling function is added to the leveling valves 14a and 14b. When the energization to the solenoid 22 is turned on, the leveling valves 14a and 14b are held at a neutral position where the air supply / exhaust is cut off. On the other hand, when the energization to the solenoid 22 is turned off, the leveling valves 14a and 14b (Status).
[0017]
For the air springs 11 c and 11 d at the rear of the cab, a pipe 32 is provided in parallel with the leveling valve 14 b, and the air springs 11 c and 11 d are connected to the air reservoir 16 via the second electromagnetic valve 17 and the throttle 18. The second solenoid valve 17 blocks the passage when the energization to the solenoid 23 is off, and communicates the passage when the energization to the solenoid 23 is turned on.
[0018]
The solenoids 21 of the first solenoid valves 12a to 12d and the solenoids 22 of the leveling valves 14a and 14b are wired to a power source via a brake switch 19 that is turned on when the brake is in an operating state. The solenoid 23 of the second electromagnetic valve 17 is wired to the power supply via the brake switch 19 and a limit switch 20 in series therewith. The limit switch 20 is for detecting a nose dive exceeding a certain level. In this example, the limit switch 20 is turned on when the air springs 11c, 11d at the rear of the cab stroke to the extension side beyond a predetermined value. Reference numeral 24 denotes an air pump.
[0019]
With such a configuration, when the brake switch 19 and the limit switch 20 are OFF (normal time), the first solenoid valves 12a to 12d, the leveling valves 14a and 14b, and the second solenoid valve 17 are connected to the solenoids 21 to 23, respectively. Power is turned off. The air springs 11a to 11d communicate with the sub tanks 13a to 13d via the first solenoid valves 12a to 12d, and softly support the cab with a small spring constant.
[0020]
For the swaying and tilting of the cab, the leveling valves 14a and 14b are switched mechanically and function to maintain the cab height in a constant horizontal state by supplying and exhausting air from the air springs 11a to 11d. . Since the second solenoid valve 17 keeps the pipe 32 in parallel with the leveling valve 14b in a disconnected state, the leveling function described above is not impaired.
[0021]
If the brake is applied while driving, the front part of the cab will sink due to the inertial force ahead. At this time, when the brake switch 19 is turned on, the solenoid 21 of the first solenoid valves 12a to 12d and the solenoid 22 of the leveling valves 14a and 14b are energized. Thus, the first electromagnetic valves 12a to 12d block the passage, and the leveling valves 14a and 14b maintain the neutral position. The air springs 11a to 11d are disconnected from the sub tanks 13a to 13d, and suppress the nose dive of the cab in a sealed state with a large spring constant. Therefore, the swing back after nose dive is also reduced.
[0022]
Along with the nose dive, the rear part of the cab is pushed upward. The air springs 11c and 11d at the rear of the cab swell in a sealed state at first, but when the stroke reaches a predetermined value or more, the solenoid 23 of the second solenoid valve 17 is energized by turning on the limit switch 20 in addition to the brake switch 19. Is done. As a result, air is supplied from the air reservoir 16 to the air springs 11c and 11d swelled at the rear of the cab through the second electromagnetic valve 17 and the throttle 18, so that the air springs 11c and 11d at the rear of the carb Get a shakeback. The air springs 11c and 11d are compressed while pushing out air by swinging back. In this process, even if the brake switch 19 is turned on, the limit switch 20 is turned off, so that the communication with the air reservoir 16 is connected to the second electromagnetic valve 17. Therefore, the momentum of swinging back is weakened and the bottom is not generated.
[0023]
At the time of swing back after nose dive, the throttle is applied to the air pushed out from the air springs 11c, 11d to the air reservoir 16 until the second electromagnetic valve 17 blocks the passage to the air reservoir 16, so that the swing back momentum is exerted. It can attenuate effectively. When the nose dive swings back, the brake switch 19 is also turned off, so that the normal state is restored, and the air springs 11a to 11d are communicated with the sub tanks 13a to 13d via the first electromagnetic valves 12a to 12d, respectively. 14a and 14b supply and exhaust air from the air springs 11a to 11d, so that the height of the cab is returned to a constant horizontal state.
[0024]
Accordingly, even during sudden braking, the nose dive and its swing back can be kept small, and the spring constant of the air spring can be set small in order to increase the soft riding comfort of the cab.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a conventional example.
[Explanation of symbols]
11a to 11d Air springs 12a to 12d First solenoid valves 13a to 13d Sub tanks 14a and 14b Leveling valve 16 Air reservoir 17 Second solenoid valve 18 Restriction 19 Brake switch 20 Limit switches 21 to 23 Solenoid

Claims (2)

An air spring that supports the front part of the cab, an air spring that supports the rear part of the cab, a leveling valve interposed in a passage connecting the air spring and the reservoir tank in the front part of the cab, and an air spring and a reservoir in the rear part of the cab A leveling valve installed in the passage connecting the tank and a sensing mechanism that switches each leveling valve independently to supply and exhaust air on the air spring side to maintain the cab height in a constant horizontal state. A normally open type first solenoid valve interposed in each of the passages connecting the sub-tanks for each air spring, an air cylinder at the rear of the cab, and a reservoir tank. A normally closed type second solenoid valve interposed in a passage connecting the leveling valve in parallel with each other; During the operation of the rake, the exciting circuit of the first solenoid valve is closed and the air supply / exhaust of each leveling valve is shut off, and the air spring at the front part of the cab or the rear part of the cab is stroked to a predetermined value or more. And a means for closing the excitation circuit of the solenoid valve . The cab suspension device according to claim 1 , further comprising a throttle that acts on air passing through the second electromagnetic valve .

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