JPH08295115A - Suspension control device for tractor - Google Patents

Abstract

PURPOSE: To reduce nose-up on starting and nose-dive on braking by changing over the damping force characteristics of a suspension mechanism of the tractor front to hard and the damping force characteristics of the tractor rear part to soft compared with the suspension characteristics in normal driving in starting or braking. CONSTITUTION: Decision means 5c for deciding the control contents of suspension for the front and rear wheels of a tractor based on signals from a speed sensor 3, and a stop lamp switch 4 outputs a front wheel shock absorber characteristics change-over signal to a front wheel shock absorber 2a via driving means 5d, and a rear wheel shock absorber characteristics change-over signal to a rear wheel shock absorber 2b via driving means 5e to perform suspension control for the tractor. Namely, front wheel shock absorber 2a characteristics are changed over to soft, and rear wheel shock absorber 2b characteristics are changed over to hard in normal driving. Front and rear wheel shock absorber characteristics are reversely changed over in contrast with the above in starting, braking, stopping the tractor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for a tractor, and more particularly to a technique for suppressing nose-up when starting and nose-dive when braking.

[0002]

2. Description of the Related Art Vehicles for connecting a tractor and a trailer are roughly classified into two types, a semi-trailer type and a full trailer type, depending on the connecting method. Here, the tractor in the semi-trailer system is a completely dedicated vehicle that pulls the trailer, and is installed almost at the rear of the chassis that increases the traction force by installing a high-power engine or increasing the gears and reduction ratio. It is known that a coupler called the fifth wheel is attached near the upper part of the shaft, and it does not require a space for loading platform and it is generally known that the wheelbase is made as short as possible in order to improve the operability. Further, the trailer is a vehicle having only a rear axle, and at the time of connection, a part of the load and the weight of the load is directly supported by the tractor.

[0003]

By the way, in the semi-trailer type tractor, the suspension characteristics of the rear wheels are relatively hard as compared with the front wheels in order to support a part of the load of the trailer being pulled and the weight of the load. In addition to this, a pitching moment is generated due to the inertial force of the trailer that is being pulled when starting and braking, so the nose-up of the front part of the tractor lifts up significantly when starting, compared to when using the tractor alone, and the front of the tractor during braking. The nose dive where the part greatly sinks (see Fig. 5). Due to such nose-up or nose-dive, there is a problem that the cab in which an occupant is moved up or down greatly, which deteriorates the riding comfort and makes driving operation difficult.

Here, as a technique for controlling the attitude change of the vehicle, for example, there is a technique for controlling the rolling by changing the characteristic of the suspension mechanism of the vehicle based on the signal of the rolling sensor provided in the center of the vehicle. (See Japanese Utility Model Laid-Open No. 3-204). Therefore, in view of the above problems, the present invention changes the damping force characteristics of the suspension mechanism for the front and rear wheels of the tractor without impairing the riding comfort during normal traveling, thereby increasing the nose at starting and braking. The purpose of this is to reduce the nose dive of the vehicle (see FIG. 5).

[0005]

Therefore, the invention according to claim 1 is provided with suspension mechanisms of variable damping force at the left and right ends of the tractor between the sprung and unsprung front and rear, respectively.
In a suspension device for a tractor having a switching mechanism that switches at least hard or soft the damping force characteristic of the suspension mechanism, a state detecting means for detecting a running state of the tractor, and a detected running state when starting or braking, Compared with the suspension characteristics during normal running, the suspension control means is configured to control the damping force characteristics of the suspension mechanism at the front of the tractor to be hard and the damping force characteristics of the suspension mechanism at the rear of the tractor to be soft. .

[0006]

According to the first aspect of the invention, when the tractor starts and brakes, the damping force characteristic of the suspension mechanism at the front of the tractor is harder than that of the suspension mechanism at the time of normal running, and the damping force of the suspension mechanism at the rear of the tractor is hard. By softening the characteristics, tractor nose up and nose dive are reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows the overall structure of a semi-trailer type tractor showing an embodiment of the present invention. The semi-trailer type tractor 1 pulls the trailer 6 by a coupler 1a called a fifth wheel, and the front and rear wheel suspension devices of the tractor 1 have soft and hard damping force characteristics as a damping force variable suspension mechanism. The shock absorbers 2a and 2b having a mechanism capable of switching between two stages are provided.

Further, as a structure for controlling the suspension device of the tractor 1, a vehicle speed sensor 3 for detecting the vehicle speed of the tractor 1 as a state detecting means and a stop lamp switch 4 for detecting that a braking operation of the tractor 1 is performed. Is installed, and the outputs of the vehicle speed sensor 3 and the stop lamp switch 4 are input to a controller 5 that controls the vehicle of the tractor 1 and that also has a function as suspension control means. On the other hand, the controller 5 determines the content of suspension control of the tractor, and the control output thereof is output to the shock absorbers 2a, 2b.

FIG. 2 shows a block diagram of suspension control contents of the embodiment according to the present invention. The controller 5 for controlling the suspension of the tractor 1 is a vehicle speed signal input means 5a as a means for inputting signals from various sensors.
A stop lamp signal input means 5b, a determination means 5c for determining suspension control contents based on various detected signals, and a front wheel shock absorber drive means as means for outputting a signal for suspension control by the determination means 5c. 5d and rear wheel shock absorber drive means 5e.

The output signal of the vehicle speed sensor 3 is input to the determination means 5c via the vehicle speed signal input means 5a, and the output signal of the stop lamp switch 4 is input to the determination means 5c via the stop lamp signal input means 5b. It Based on the signals from the vehicle speed sensor 3 and the stop lamp switch 4,
The determination means 5c that determines the suspension control content of the front and rear wheels of the tractor 1 sends the front wheel shock absorber characteristic switching signal as the control content of the front wheel suspension device to the front wheel shock absorber 2a via the front wheel shock absorber drive means 5d and the rear wheel. A rear-wheel shock absorber characteristic switching signal as a suspension device control content is output to the rear-wheel shock absorber 2b via the rear-wheel shock absorber drive means 5e to perform suspension control of the tractor 1.

In the above embodiment, the vehicle speed sensor as the vehicle speed detecting means and the stop lamp switch as the braking state detecting means are used as the state detecting means for detecting the traveling state (starting, braking, stopping, etc.) of the tractor. However,
Instead of this, a longitudinal acceleration sensor or the like may be used as a longitudinal acceleration detecting means for detecting the longitudinal acceleration of the tractor.

FIG. 3 shows a flow chart of the suspension control contents of the embodiment according to the present invention. In step 1 (abbreviated as S1 in the figure; the same applies hereinafter), the vehicle speed sensor 3
The vehicle speed sensor signal is read, and in step 2, the stop lamp signal is read from the stop lamp switch 4.

In step 3, based on the stop lamp signal, it is judged whether or not the stop lamp is ON, that is, whether or not braking is in progress. If braking is in progress, step 7 follows. If braking is not in progress, step 4 follows. In step 4, it is determined whether or not a predetermined time T ₁ seconds has elapsed after the stop lamp was turned off. If yes, the process proceeds to step 5, and if not, the process proceeds to step 7. In step 5, the absolute value of the vehicle speed V | V |, it is determined whether or not a predetermined speed V ₁ or more, to step 6 if V ₁ or more, the routine proceeds to step 7 if it is less than V _1. Through the processes of steps 3 to 5, it is determined whether the tractor branches to the suspension characteristics during normal traveling (step 6) or the suspension characteristics during starting, braking and stopping (step 7).

In step 6, the front wheel shock absorber characteristics are switched to soft (SOFT) and the rear wheel shock absorber characteristics are switched to hard (HARD) in order to obtain the suspension characteristics for normal traveling of the tractor, and the process returns.
In step 7, the front wheel shock absorber characteristics are switched to hard (HARD) and the rear wheel shock absorber characteristics to soft (SOFT) in order to obtain suspension characteristics when the tractor starts, brakes, and stops, and then returns.

By the above-described processing, the tractor makes the front wheel shock absorber soft and the rear wheel shock absorber hard during normal driving, and makes the front wheel shock absorber hard and the rear wheel shock absorber soft at the time of starting, braking and stopping. The control is performed accordingly (see FIG. 4).
With this control, when the inertial force of the trailer pulled during starting and braking acts on the tractor, the suspension of the front wheels becomes hard and the suspension of the rear wheels becomes soft, so the pitching center approaches the front wheels, and the nose up and nose are reduced. Dive is reduced.

[0016]

As described above, according to the first aspect of the present invention, when the tractor starts and brakes, the damping force characteristic of the suspension mechanism at the front of the tractor is harder than the suspension characteristic during normal running. In addition, by softening the damping force characteristics of the suspension mechanism at the rear of the tractor, the rear suspension mechanism enters a pitching mode that reduces the nose up or nose dive of the tractor and reduces the nose up and nose dive of the tractor. The upward movement or the downward movement of the cab in which the occupant is located is reduced, the riding comfort is improved, the driving operation is facilitated, and the driving fatigue is also reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a semi-trailer type tractor showing an embodiment of the present invention.

FIG. 2 is a block diagram showing the suspension control contents of the above.

FIG. 3 is a flowchart showing the suspension control contents of the above.

[Fig. 4] Content controlled by the processing of the above flowchart

FIG. 5 is a diagram comparing the problems of the prior art of a semi-trailer type tractor and the effects of the present invention.

[Explanation of symbols]

 2 (2a, 2b) Shock absorber 3 Vehicle speed sensor 4 Stop lamp switch 5 Controller

Claims (1)

[Claims] 1. A front and rear left / right portion between the sprung and unsprung portions of a tractor.
In a tractor suspension device having a suspension mechanism of variable damping force at each of the right ends, and having a switching mechanism for switching the damping force characteristic of the suspension mechanism to at least hard or soft, state detection means for detecting a running state of the tractor, When the detected running condition is when starting or braking, the damping force characteristic of the suspension mechanism at the front of the tractor is made harder and the damping force characteristic of the suspension mechanism at the rear of the tractor is made softer than the suspension characteristic at the time of normal running. A suspension control device for a tractor, comprising: a suspension control unit that performs switching control.