JPH0612136B2 - Elastic support device for cab - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cab elastic supporting device, and more particularly to a cab elastic supporting device adapted to support a cab on a frame via a spring.

[Prior art]

The load of the truck is relatively large compared to the weight of the vehicle body. Therefore, the axle is suspended by a leaf suspension device including a leaf spring having a large spring constant and high durability. Therefore, when the cab is directly mounted on the front end side of the frame of such a truck, the vibration from the road surface is transmitted to the cab through the hard leaf spring and the frame, which deteriorates the riding comfort of the cab.

Therefore, as disclosed in Japanese Utility Model Laid-Open No. 58-157874, the cab is mounted on a frame via an elastic supporting device composed of a coil spring, or disclosed in Japanese Utility Model Laid-Open No. 59-27974. As described above, the cab is mounted on the frame via the air spring.

[Problems to be Solved by the Invention]

The suspension system for a cab disclosed in Japanese Utility Model Laid-Open No. 58-157874 makes it possible to previously adjust the spring constants of coil springs that support the cab at four points, and shocks arranged in parallel with these springs. The absorber damping force can also be adjusted to an appropriate value in advance. However, this device cannot always change the spring constant and the damping force of the shock absorber to an optimum state according to the running state of the vehicle and the state of the road surface.

The cab suspension device disclosed in Japanese Utility Model Laid-Open No. 59-27974 detects lateral acceleration applied to the cab and controls the supply and discharge of air into the left and right air springs according to the acceleration. By
In particular, the influence of lateral acceleration on the occupant during turning is reduced.

However, such a device cannot adjust the spring constant of the air spring according to the acceleration in the front-rear direction or the vertical direction, and also cannot adjust the spring constant of the air spring according to the condition of the road surface. is there. Further, according to such a device, there is a problem that the suspension characteristics of the cab cannot be manually set according to the occupant's preference.

[Object of the Invention]

The present invention enables the suspension characteristics of the cab to be always optimized according to the running state of the vehicle and the state of the road surface, and the suspension characteristics of the cab can be controlled according to the occupant's preference. It is an object to provide an elastic support device.

[Structure of Invention]

The present invention relates to an elastic support device for a cab configured to support the cab on a frame via a spring, wherein a common load point of the cab is received by a plurality of springs, and at least one of the plurality of springs is used. A cylinder that changes the initial displacement of one spring, a pressure source of the working fluid supplied to the cylinder, and a control valve that controls the supply and cutoff of the working fluid are provided, and the cylinder controls the springs of the plurality of springs. In order to change the total spring constant, a damping force variable type shock absorber is arranged in parallel with each of the plurality of springs receiving the common load point, and an actuator for changing the damping force is provided, and the control valve and The actuator and the actuator are respectively controlled by a computer, Are three types of acceleration sensors for respectively detecting vertical, lateral, and longitudinal accelerations applied to the cab, an unevenness detection sensor for detecting unevenness on the road surface, a manual operation means, and a manual and automatic selection switch. When the selector switch is connected and the selection switch is automatically switched, the control is performed by the computer according to the detection of the acceleration sensor that detects three types of acceleration applied to the cab and the unevenness detection sensor that detects unevenness of the road surface. The computer controls the valve and the actuator, and the control of the control valve by the computer supplies the working fluid to the cylinder or discharges it from the cylinder according to the external force applied to the spring, and when the external force decreases, the working fluid is supplied to the cylinder. Spring characteristics by returning the working fluid to the original state It is an arbitrary spring constant setting associated with the change, and when the selection switch is manually switched, the computer controls the control so that the characteristic of the elastic support device of the cab becomes the characteristic input by the manual operation means. The present invention relates to an elastic support device for a cab, which is characterized in that a valve and the actuator are controlled.

[Action]

When the selection switch is automatically switched, the cab is elastically supported with an optimal spring constant and the damping force of the shock absorber is adjusted to an optimal value according to the running state of the vehicle and the state of the road surface. When the selection switch is switched to the manual mode, the characteristic of the elastic support device of the cab is maintained so as to have the characteristic input by the manual operation means.

〔Example〕

 The present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 1 shows a truck in which a cab is supported by an elastic supporting device according to an embodiment of the present invention, and a cab 2 is provided at a front end portion of a frame 1 of the truck.
Is being supported. The frame of the cab 2 is composed of a main sill 3, and both the front end and the rear end of the main sill 3 are supported by the coil suspension device 4. A shock absorber 5 is attached to each of these coil suspension devices 4 in parallel. The characteristics of the coil suspension device 4 and the shock absorber 5 are both controlled by a controller 6 composed of a microcomputer.

At the input side of the microcomputer 6 for changing the characteristics of the coil suspension device 4 and the shock absorber 5, as shown in FIG. 2, a vehicle speed sensor 7, a road surface unevenness detection sensor 8 and a vertical direction of the floor of the cab 2 are arranged. The acceleration sensor 9 for detecting the acceleration of the cab, the acceleration sensor 10 for detecting the lateral acceleration of the cab, and the acceleration sensor 11 for detecting the acceleration of the cab 2 in the front-rear direction are connected to each other. The microcomputer 6 changes the characteristics of the coil suspension device 4 and the shock absorber 5 based on the detection outputs of 7 to 11.

The microcomputer 6 controls the motors 12 and 13, respectively. And these motors 1
The output shafts 2 and 13 are connected to the control valves 14 and 15, respectively. The control valves 14 and 15 are connected to an oil pump 17 that pressurizes and supplies the oil in the reservoir 16, and a line through which the oil pressurized by the oil pump 17 is supplied to the hydraulic cylinders 18 and 19. It can be attached to. The hydraulic cylinder 18 is provided in the coil suspension device 4 and changes the spring constant of the suspension device 4. On the other hand, the hydraulic cylinder 19 is adapted to change the throttle of the shock absorber 5, and thereby to change the damping force of the shock absorber 5.

Next, the coil suspension device 4 in which the spring constant is changed will be described in more detail.
As shown in the figure, a flange 20 is provided on the lower end side of the hydraulic cylinder 18, and a groove 21 extending in the circumferential direction is formed on the lower surface of the flange 20. The groove 21 receives the first coil spring 22. A piston 23 is held inside the hydraulic cylinder 18, a protrusion 24 is formed on the lower surface of the piston 23, and a step 25 on the outer peripheral side of the protrusion 24 is formed.
Is adapted to receive the upper end of the second coil spring 26.

On the other hand, the lower ends of the two coil springs 22 and 26 are both received by the spring receiver 27. The lower end of the first coil spring 22 is received by the groove 28 of the spring receiver 27, while the lower end of the second coil spring 26 is the protrusion 2 of the spring receiver 27.
It is adapted to be received by the step portion 30 on the outer peripheral side of 9.

In the above-described structure, the driver's seat of the cab 2 is provided with a manual and automatic selection switch, and this switch can be switched to manual or automatic. When the mode is switched to the manual mode, the exerciser inputs the running condition or the characteristic into the microcomputer 6, and the motor 12,
The hydraulic cylinders 18 and 19 are controlled by 13 and the control valves 14 and 15, respectively. The hydraulic cylinder 18 changes the spring constant of the suspension device 4, and the hydraulic cylinder 19 changes the throttle of the shock absorber 5 to change its damping force. Therefore, both the coil suspension device 4 and the shock absorber 5 are set to the desired spring constant and damping force.

On the other hand, when the selection switch is automatically switched, the microcomputer 6 controls the motors 12 and 13 according to the detection of the sensors 7 to 11 connected to the input side of the microcomputer 6. become.
Since these motors 12 and 13 are designed to control the control valves 14 and 15, the hydraulic cylinders 18 and 1 are controlled via the control valves 14 and 15.
9 is controlled so that the spring constant and the damping force of the support device 4 formed of a coil spring and the shock absorber 5 are automatically controlled. The spring constant of the coil suspension device 4 increases as the hydraulic pressure of the hydraulic cylinder 18 increases. Further, the damping force of the shock absorber 5 becomes higher as the throttle is greatly reduced by the hydraulic cylinder 19.

Next, a specific operation of changing the spring constant of the support device 4 including a coil spring will be described. The spring constants of the first coil spring 22 and the second coil spring 26 shown in FIG. 3 are K ₁ and K ₂ , respectively. Second coil spring 2
The upper end of 6 is the piston 2 of the hydraulic cylinder 18 as described above.
It is supposed to be received by 3. When the pressure of the oil inside the hydraulic cylinder 18 is P, it balances with the external force F of this elastic support device, and the spring flexure causes the external force F =
It is assumed that the reference height, that is, the distance in the height direction between the lower end of the flange 20 and the upper end of the spring receiver 27 is x ₀ , because the reference height is deflected by x ₁ .

In such a state, if the external force F is increased or decreased while the internal pressure P of the cylinder 18 is kept constant, the hydraulic cylinder 18 behaves as a rigid body, and the spring characteristic becomes a straight line I ₁ passing through the point Q _{1 in} FIG. Becomes K = K ₁ + K ₂ ... (1).

Next, when the external force F is kept constant and the internal pressure P of the cylinder 18 is decreased by ΔP, the second coil spring 26 lifts the piston 23 of the cylinder 18, and the reaction force causes the first coil spring 22 to move to a high level. Will be compressed in the vertical direction. At this time, the descending amount of the first coil spring 22 is Δx = ΔP / K ₁ ... (2), and the operating point is from the point Q ₁ (x ₁ , F) to the point Q ₂ (X ₁
Move to + Δx, F). When the external force F is increased or decreased in this state, the hydraulic cylinder 18 also behaves as a rigid body at this time, so the characteristic line passes through Q ₂ and is parallel to the straight line I _1.
It becomes ₂ .

Reduce the external force F △ F only in terms Q ₂ on the characteristic curve I ₂ Now, back to the original pressure P to increase the internal pressure of the cylinder 18 at the same time, the elastic support unit is displaced. At this time, the amount of change in the reference height of the elastic support device is calculated by dividing the external force F by ΔF.
Displacement caused by changing only the
Equivalent to the displacement Δx when the internal pressure of P is returned to P. And Q ₂ on the straight line I ₂ is the operating point by such change
From moving to _{Q 3.} The above Δx is given by the equation (2). Further, Δx ′ is given by Δx ′ = ΔF / K. Therefore, the coordinates of the point Q ₃ in FIG. 4 are (x ₁ −ΔF / K, F−ΔF). Also, the characteristic line I ₃
Assuming that the slope of is Kc (total spring constant), as is clear from FIG. here That is, an arbitrary spring constant can be obtained by arbitrarily selecting α. By inserting α for the spring constant Kc that is now required and ΔF calculated from the output of the acceleration sensor 9 in the vertical direction into an integrator, and controlling the control valve 13 for the output ΔP, the elastic supporting device is obtained. It is possible to arbitrarily set the spring constant of.

As described above, according to the elastic support device for the cab of the present embodiment, the first coil spring 22 and the second coil spring 26, which respectively support the four points of the cab 2, are formed by the above-described operation. The spring constant of the elastic support device is arbitrarily set and selected. Therefore, it becomes possible to change the damping force of the shock absorber 5 and its spring constant according to the road surface condition, the running condition of the vehicle, etc., and the elastic support is provided so as to improve the riding comfort and the steering stability. It is possible to arbitrarily select the spring constant of the device 4.

〔The invention's effect〕

As described above, according to the present invention, when the selection switch is automatically switched, the vertical acceleration, the lateral direction, and the longitudinal acceleration applied to the cab are detected by the corresponding acceleration sensors, and the state of the road surface unevenness is detected. Is detected by the unevenness detection sensor, and based on these detection outputs, the computer changes the total spring constant of multiple springs via the cylinder, and the actuator changes the damping force of the shock absorber to determine the running state of the vehicle. Alternatively, the spring constant of the elastic support device of the cab and the damping force of the shock absorber are adjusted according to the state of the road surface.

Therefore, the characteristics of the elastic support device for the cab can be maintained at the optimum characteristics depending on the running state of the vehicle and the state of the road surface unevenness. In particular, accelerations in three directions applied to the cab are detected by the corresponding acceleration sensors, respectively, and the unevenness of the road surface is also detected by the unevenness detection sensor. Therefore, it is possible to finely control the elastic support device of the cab. .

In particular, according to the present invention, the supply of the working fluid from the pressure source to the cylinder and the discharge of the working fluid are controlled by the computer via the control valve, and the working fluid is supplied to or from the cylinder according to the external force. When the external force is reduced and the working fluid supplied to the cylinder is returned to the original state when the external force is reduced, the apparent spring characteristics are changed and the spring constant of the elastic support device is set. It is possible to set the constant to an arbitrary value, and it is possible to always adjust the characteristics of the elastic support device of the cab to an optimum state by changing the spring constant together with the damping force of the shock absorber.

When the selection switch is switched to manual, the computer changes the total spring constant of a plurality of springs through the cylinder so that the characteristics input by the manual operation means are obtained, and the damping force of the shock absorber is changed by the actuator. It is possible to change and maintain the desired spring constant and damping force. Therefore, it becomes possible to set the characteristic of the elastic support device of the cab to the characteristic according to the occupant's preference.

[Brief description of drawings]

FIG. 1 is a side view of a main part of a cab of a truck provided with an elastic supporting device according to an embodiment of the present invention, FIG. 2 is a block diagram showing a control system of the elastic supporting device of the cab, and FIG. FIG. 4 is a longitudinal sectional view of a coil suspension used in a suspension device, and FIG. 4 is a graph showing the operation of this coil suspension. The names of the main parts in the drawings are as follows. 1 ...... Frame 2 ...... Cab 4 ...... Coil suspension device 5 ...... Shock absorber 6 ...... Controller (microcomputer) 7 ...... Vehicle speed sensor 8 ...... Road surface unevenness detection sensor 9 ...... Cab floor vertical acceleration sensor 10 ... Lateral acceleration sensor 11 ... Longitudinal acceleration sensor 12, 13 ... Motor 14, 15 ... Control valve 17 ... Oil pump 18, 19 ... Hydraulic cylinder 22 ... First coil spring 23 ...... Piston 26 ...... Second coil spring 31 ...... Pressure sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-167377 (JP, A) JP-A-58-121336 (JP, A) JP-A-59-63218 (JP, A) Actual development Sho-58- 157874 (JP, U) Actually opened 59-27974 (JP, U) Actually opened 59-32581 (JP, U) Actually opened 58-152406 (JP, U)

Claims (1)

[Claims] 1. An elastic support device for a cab, wherein the cab is supported by a frame via a spring, wherein a common load point of the cab is received by a plurality of springs, and a plurality of springs among the plurality of springs are provided. A cylinder for changing the initial displacement of at least one spring, a pressure source for the working fluid supplied to the cylinder, and a control valve for controlling the supply and cutoff of the working fluid are provided, and the plurality of springs are provided by the cylinder. To change the total spring constant of each of the plurality of springs receiving a common load point in parallel with a damping force variable type shock absorber, and further to provide an actuator for changing the damping force, the control valve And the actuator are respectively controlled by a computer, Is equipped with three types of acceleration sensors that detect vertical, lateral, and longitudinal accelerations applied to the cab, an unevenness detection sensor that detects unevenness on the road surface, a manual operation means, and a manual and automatic selection switch. When each of them is connected and the selection switch is automatically switched, the computer detects the acceleration of three types of acceleration applied to the cab and the unevenness detection sensor of unevenness of the road surface. The control valve and the actuator are controlled, and the control of the control valve by the computer supplies or discharges the working fluid to or from the cylinder according to the external force applied to the spring, and supplies it to the cylinder when the external force decreases. The apparent spring characteristics by returning the working fluid to the original state. Is an arbitrary spring constant setting in accordance with the change of, when the selection switch is manually switched, the computer by the computer so that the characteristics of the elastic support device of the cab becomes the characteristics input by the manual operation means. An elastic support device for a cab, characterized in that a control valve and the actuator are controlled.