JPH0737864U - Shock absorber for car cab suspension - Google Patents

Abstract

(57) [Summary] [Purpose] While effectively suppressing vibration in the bouncing mode of the cab, which is a concern when the vehicle is driven at extremely low speeds on rough roads, etc., vibration to the cab during normal driving To improve the ride comfort in the driver's seat. A valve 23 is provided in a passage 21 for communicating a pair of oil chambers 12, 13 separated by a piston 11 provided in a shock absorber 4 for connecting a frame and a cab 1. By providing the actuator 26 that drives the valve 23 and the vehicle speed sensor 29 that variably controls the opening degree of the passage 21 by operating the valve 23 via the actuator 26 based on the vehicle speed, The damping force of the shock absorber 4 is automatically changed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a shock absorber for a cab suspension of a vehicle, and more particularly to a shock absorber for a cab suspension suitable for suppressing vibration of a cab mounted on a frame of a vehicle via a spring.

[0002]

[Prior art]

 In recent years, in cars such as cab-over trucks, a cab is often mounted on a frame through a spring and a shock absorber to increase the habitability of the driver's seat. When the cab is mounted on the frame via the spring and the shock absorber as described above, it is possible to reduce the vibration transmitted from the frame to the cab and to suppress the vibration of the cab.

However, in an automobile, such as a dump truck, which steers a terrain or a road surface with large irregularities at an extremely low speed, vibration in a bouncing mode (frequency of about 0.5 to 3 Hz is slowed by the vehicle speed and road surface input). Vibration, which is the same in the following), may cause a large vertical movement of the cab.

That is, since the shock absorber used in the suspension system of the axle has been diverted to the shock absorber for the cabin suspension, the damping force of the shock absorber is increased to enhance the effect of suppressing the vibration of the cab. In that case, there was a problem that the ruggedness increased and the habitability deteriorated. If the damping force of the shock absorber is reduced in order to eliminate such a rugged feeling, bouncing mode vibration occurs and the cab vibrates greatly up and down when driving at extremely low speed on the constructed land or the road surface with large unevenness. There was a problem that it did.

Therefore, when the shock absorber used in the suspension system for the axle is diverted for the cab suspension as in the conventional art, there is a limit to improving the habitability of the cab.

[0006]

[Problems to be solved by the device]

 The present invention has been made in view of the above circumstances, and suppresses vibration in the bouncing mode of the cab, which is a concern when the vehicle is subjected to extremely low speed driving on a bad road, etc., while driving during normal driving. The challenge is to provide a shock absorber for a cab suspension that can improve the ride comfort of the seat.

[0007]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention provides a valve in a passage that connects a pair of oil chambers separated by a piston provided in a shock absorber that connects a frame and a cab. Further, an actuator for driving the valve is provided, and a vehicle speed sensor for variably controlling the opening degree of the passage by operating the valve via the actuator based on the vehicle speed is characterized.

[0008]

[Action]

 When the cab moves up and down with respect to the frame due to the flexure of the spring, the piston moves and a pressure difference occurs between a pair of oil chambers separated by a piston. When a pressure difference occurs in this way, the hydraulic oil in the high-pressure side oil chamber flows into the other oil chamber through the passage provided in the piston. In this way, the damping action is performed by the flow resistance of the hydraulic oil passing through the passage.

By the way, when the vehicle speed detected by the vehicle speed sensor is lower than a predetermined value, the actuator reduces the opening degree of the valve, and when the vehicle speed increases, the opening degree of the valve is increased. Therefore, when the vehicle is driven at a low speed, that is, when the frequency of the vibration transmitted to the cab is low, the opening of the passage becomes small, so that a high damping force is obtained, which results in the cab bouncing mode. Vibration is suppressed.

However, when the vehicle speed detected by the vehicle speed sensor becomes higher than a predetermined value, the actuator increases the opening degree of the valve by the signal from the vehicle speed sensor to reduce the resistance of the passage. Then, since the damping force of the shock absorber becomes small, the vibration transmitted from the frame to the cab via the shock absorber is reduced and the so-called lumpy feeling is suppressed.

Therefore, even when the damping force is reduced when the vehicle speed is high to suppress the lumpy feeling, the damping force is increased and corrected when the vehicle speed decreases, so that the vibration of the cab in the bouncing mode occurs. It is suppressed and the riding comfort of the driver's seat is improved.

[0012]

【Example】

 Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a shock absorber for a cab suspension of a vehicle according to the present invention, FIG. 2 is a schematic side view of an automobile illustrating a mounted state of the shock absorber according to the present invention, and FIG. 3 is FIG. 3 is a sectional view of the valve shown in FIG.

In these figures, by mounting the cab 1 on the frame 2 via the spring 3, the vibration transmitted from the frame 1 to the cab 2 is suppressed. In addition, by connecting the frame 1 and the cab 2 via the shock absorber 4, the vibration of the cab 2 is suppressed and the comfortability of the driver's seat is enhanced.

A flange 6 fixed to the outer surface of the outer tube 5 of the shock absorber 4 is sandwiched and held between brackets 7 fixed to the frame 2 via a rubber cushion 8. Further, an inner tube 9 is provided inside the outer tube 5 to form a gas chamber 10 between the tubes 5 and 9, and the piston 10 is slidably attached to the inner tube 9 so that the inner tube 9 can be slidably attached. The inside is divided into an upper oil chamber 12 and a lower oil chamber 13.

As described above, the piston 11 that divides the inner tube 9 into the upper oil chamber 12 and the lower oil chamber 13 is provided with a large-diameter communication passage 14 and a small-diameter communication passage 15. Then, the check valve 16 is attached to the upper surface of the large-diameter communication passage 14, and the check valve 17 is attached to the lower end of the small-diameter communication passage 15, so that when the piston 11 moves downward in FIG. Only the communication passage 14 is opened, and when the piston 11 moves upward, only the communication passage 15 having a small diameter is opened.

Further, the lower end of the piston rod 18 is fastened and fixed to the piston 11 with the piston nut 19, and the upper end of the piston rod 18 is connected to the cab 1 via the rubber cushion 20. When the cab 1 relatively moves, the piston 11 moves up and down in the inner tube 5.

As described above, the piston rod 18 connecting the cab 1 to the piston 11 is made of a hollow material, and the lower end of the auxiliary passage 21 formed in the piston rod 18 is held in communication with the lower oil chamber 13 and An opening 22 that connects the passage 21 and the upper oil chamber 12 is provided in the middle portion of the piston rod 18. When the cylindrical valve 23 is rotatably fitted and held in the auxiliary passage 21 and the ports 24 and 25 provided in the valve 23 are switched to face the opening 22, the upper oil chamber by the auxiliary passage 21 is formed. The communication area between 12 and the lower oil chamber 13 is changed.

An actuator 26 is fastened and fixed to an upper end portion of the piston rod 18 with a nut 27, and an output shaft of the actuator 26 and the valve 23 are connected via a shaft 28. The actuator 26 is composed of, for example, a servo motor, and is controlled by a controller 30 to which the output of the vehicle speed sensor 29 is supplied.

When the vehicle speed detected by the vehicle speed sensor 29 is higher than, for example, 15 km / h, the controller 30 assists by rotating and holding the valve 23 at a position where the port 24 overlaps the opening 20 as shown in FIG. Although the communication area by the passage 21 is increased, the valve 23 is turned clockwise in FIG. 3 so that only the small-diameter port 25 overlaps with the opening 20 when the vehicle speed detected by the vehicle speed sensor 29 is lower than 15 km / h at an extremely low speed. The actuator 26 is controlled so that the communication area by the auxiliary passage 21 is reduced by rotating the actuator 26.

In the shock absorber for a cab suspension of an automobile configured as described above, when the cab 1 moves up and down with respect to the frame 2 due to the bending of the spring 3, the piston 11 fitted in the inner tube 5 moves vertically. To do. Then, a pressure difference is generated between the upper oil chamber 12 and the lower oil chamber 13 which are separated by the piston 11.

That is, when the cab 1 is going to move upward with respect to the frame 2, the pressure in the upper oil chamber 12 becomes higher than the pressure in the lower oil chamber 13, so that the operating oil in the upper oil chamber 12 is It flows into the lower oil chamber 13 through the communication passage 15 and the auxiliary passage 21. On the other hand, when the cable 1 is about to move downward with respect to the frame 2, the pressure in the upper oil chamber 12 becomes lower than the pressure in the lower oil chamber 13, so that the hydraulic oil in the lower oil chamber 13 communicates with the communication passage. 14 and the auxiliary passage 21 to flow to the upper oil chamber 12, and the damping action is performed by the flow resistance of the hydraulic oil at this time.

Further, when the vehicle is operating in a normal state, the communication area by the auxiliary passage 21 becomes large, but when the vehicle speed becomes lower than 15 km / h, the opening degree of the valve 23 becomes smaller and the auxiliary passage 21 becomes smaller. The communication area becomes smaller. Therefore, even when the damping force of the shock absorber 4 is reduced in order to suppress the vibration transmitted from the frame 2 to the cab 1 during normal traveling and suppress the lumpy feeling, the vehicle is used for extremely low speed traveling. Then, the communication area between the pair of oil chambers 12 and 13 is controlled to decrease, and the damping force of the shock absorber 4 is automatically corrected to increase. Therefore, in the bouncing mode of the cab 1, which is a concern during extremely low speed running, Vibration is suppressed.

In other words, in the conventional shock absorber for suspension of an axle, if the damping force in the normal running state is reduced to eliminate the lumpy feeling, the damping force during extremely low speed traveling also decreases. Therefore, it is difficult to sufficiently suppress the vibration of the cab in the bouncing mode. If the damping force of the shock absorber is increased in order to suppress the vibration in the bouncing mode of the cab, the vibration is easily transmitted from the frame to the cab via the shock absorber, so that the lumpy feeling can be avoided. It had the drawback of becoming difficult.

However, in the case where the communication area between the upper oil chamber 12 and the lower oil chamber 13 is changed in response to the vehicle speed as in the present invention, the maximum damping force during normal driving is not increased. Since the damping force at low speed traveling can be increased and corrected, the vibration in the bouncing mode of the cab, which is a concern during extremely low speed traveling, can be effectively suppressed while suppressing the rugged feeling.

In the embodiment, the large-diameter communication passage 14 and the small-diameter communication passage 15 are provided to change the damping force when the shock absorber 4 expands and contracts. However, the damping force in both directions can be changed. Can be the same. Further, in the embodiment, the auxiliary passage 21 is provided in addition to the communication passages 14 and 15, and the damping force is changed by changing the opening degree of the auxiliary passage 21. The damping force can be variably controlled by directly changing it.

Further, in the embodiment, the opening degree of the auxiliary passage 21 is controlled to be increased / decreased to change the damping force, but the auxiliary passage 21 may be opened / closed to change the damping force. Furthermore, in the embodiment, the inner tube 9 is provided inside the outer tube 5 to form the gas chamber 10 between the tubes 5 and 9, and the gas chamber 10 and the lower oil chamber 13 are connected to the base valve 31. The present invention is applied to a twin-tube type gas-filled shock absorber provided with the above, but the present invention can also be applied to a mono-tube type gas-filled shock absorber or a twin-tube type shock absorber.

When the spring 3 for suspending the cab 1 on the frame 2 is composed of a coil spring as shown in the embodiment, the cab 1 can be highly self-sustaining, so that the frame 2 and the cab 1 are connected to each other. Although the mechanism can be simplified, the cab 1 can be mounted on the frame 2 by using an air spring excellent in the function of blocking vibrations, thereby making the cab 1 more comfortable.

[0028]

[Effect of device]

 As is clear from the above description, according to the shock absorber of the present invention, the damping force of the shock absorber is automatically changed according to the traveling speed of the vehicle. It is possible to effectively suppress the vibration of the bouncing mode of the cab, which is a concern when running at extremely low speeds on terrain or roads with large unevenness, while suppressing the above.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a shock absorber for a cab suspension of an automobile according to the present invention.

FIG. 2 is a schematic side view of an automobile illustrating a mounted state of a shock absorber according to the present invention.

3 is a cross-sectional view of the valve shown in FIG.

[Explanation of symbols]

 1 Cab 2 Frame 3 Spring 4 Shock Absorber 5 Outer Tube 6 Flange 7 Bracket 8 Rubber Cushion 9 Inner Tube 10 Gas Chamber 11 Piston 12 Upper Oil Chamber 13 Lower Oil Chamber 14, 15 Communication Channel 16, 17 Check Valve 18 Piston Rod 19 Piston nut 20 Rubber cushion 21 Auxiliary passage 22 Opening 23 Valve 24, 25 port 26 Actuator 27 Nut 29 Vehicle speed sensor 30 Controller 31 Base valve

Claims (1)

[Scope of utility model registration request] 1. In a vehicle having a cab mounted on a frame via a spring and a shock absorber, a passage communicating with a pair of oil chambers separated by a piston provided in the shock absorber, and a valve provided in the passage. A shock absorber for a cab suspension of an automobile, comprising: an actuator that drives the valve; and a vehicle speed sensor that variably controls the opening of the passage by operating the valve based on the vehicle speed via the actuator.