JP3049896B2 - Large bump control method for electronically controlled suspension - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large bump control system for an electronically controlled suspension.

[0002]

2. Description of the Related Art In recent years, general public vehicles have become more sophisticated, and user demands for driving operability during running, stability of a vehicle body, riding comfort, and the like have become more severe. In order to respond to such user demands, various electronically controlled suspensions have been developed for controlling the posture of the vehicle body during traveling by controlling the hardness of the suspension of the vehicle, that is, the damping force of the suspension damper by a computer.

In such an electronically controlled suspension, large bump control is employed as a means for achieving both traveling performance on rough roads and riding comfort. The large bump control is directly aimed at suppressing a large change in vehicle height when the vehicle gets over a large projection road surface.

Here, a conventional large bump control method will be described with reference to FIG.

When the suspension dampers for the left and right front and rear wheels are both in the soft mode, the magnitude of the output signal of the acceleration sensor (vertical G sensor) for measuring the vertical acceleration of the vehicle is equal to or greater than a certain value, and the state is greater than a certain time. In the subsequent case, the suspension dampers for the left, right, front and rear wheels are simultaneously switched to the hard mode. This is intended to suppress a large change in vehicle height by increasing the damping force by setting the suspension damper in the hard mode. After switching the hard mode, the suspension dampers of the left and right front and rear wheels are simultaneously switched to the soft mode after a lapse of a predetermined time. This is to make the riding comfort on a normal flat road soft. At this time, the state returns to the state before the large bump control, and the same control is performed when the large bump control condition occurs again.

[0006]

In the above-mentioned conventional large bump control system, when the front wheel rides on a large projection road surface or the like and bumps and the vertical acceleration becomes large, the suspension dampers for the left and right front and rear wheels are simultaneously hardened. Therefore, when the rear wheel rides on the large protrusion or the like, the damper on the rear wheel side is already hard. For this reason, when riding on the rear wheel, there is no one that absorbs the energy of thrust, that is, there is no means for alleviating the shock at the time of riding on the rear wheel, and the large shock is transmitted to the occupant, and there is a disadvantage that the riding comfort is reduced.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the disadvantages of the prior art, to reduce the feeling of thrust when riding on the rear wheels, and to suppress large changes in vehicle height by controlling a large bump of an electronically controlled suspension. It is to provide a method.

[0008]

According to the large bump control method of the electronic control suspension of the present invention, a vertical acceleration measuring means for measuring a vertical acceleration applied to a vehicle body during running of the vehicle, and a vehicle speed measuring means for measuring a running speed of the vehicle. Means and a predetermined calculation based on each output signal from both measuring means, and the mode of the four suspension dampers respectively provided on the left, right and front and rear wheels of the vehicle is hardened or softened via the respective damping force switching means. A damping force switching control means for controlling switching to a mode, wherein the damping force switching control means receives an output signal of the vertical acceleration measuring means, and a state in which the value of the vertical acceleration is equal to or more than a certain value is longer than a certain time If it is determined that the following large bump control condition has occurred, the suspension dampers for the left and right front wheels are switched to hard mode. After the switching, the suspension dampers for the left and right rear wheels are switched to the hard mode after a lapse of a set time determined based on a predetermined function using the vehicle speed as a parameter. Means to switch the damper to the soft mode at the same time,
It is intended to achieve the above-mentioned object.

[0009]

Normally, the damping force switching control means sets the suspension dampers of the four wheels to the soft mode. In this state, when the damping force switching control means determines that a large bump control condition in which a state where the magnitude of the vertical acceleration is equal to or more than a certain value continues for a certain time or more has occurred based on the output from the vertical acceleration measuring means, the left and right front wheels are controlled. Switch the suspension damper to hard mode. Next, the damping force switching control means also switches the suspension dampers for the left and right rear wheels to the hard mode after a lapse of a set time determined based on a predetermined function using the vehicle speed as a parameter from the switching. And
After a lapse of a predetermined time from the occurrence of the large bump control condition, a lapse of a certain period of time (a period long enough to suppress a change in vehicle height caused by overcoming of a protrusion), and simultaneously the suspension dampers for the four wheels are set to the soft mode. Switch to

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the configuration of an embodiment of an electronically controlled suspension for implementing the large bump control system according to the present invention. In this embodiment, a vertical acceleration sensor (hereinafter, referred to as a “vertical G sensor”) 10 as vertical acceleration measuring means for measuring vertical acceleration applied to a vehicle body when the vehicle 1 (see FIG. 2) travels, and the vehicle 1 Speed sensor 20 as a vehicle speed measuring means for measuring the traveling speed of the vehicle
A predetermined calculation is performed based on the output signals from the upper and lower G sensors 10 and the vehicle speed sensor 20, and four suspension dampers 41, 42, 43, 44 ( The first to fourth damping force switching actuators 40, 41, 42, 4 as respective damping force switching means are used in the mode of FIG. 2).
And a suspension controller 30 (hereinafter, abbreviated as "controller" as necessary) as a damping force switching control means for controlling to switch to a hard or soft mode via the control unit 3. In FIG. 2, reference numeral 2 indicates a steering wheel, and reference numeral 3 indicates a steering sensor.
Reference numerals 51 and 52 denote the suspension dampers 4.
The springs are shown in 1 and 42 respectively.

Next, the large bump control method according to the present invention will be described with reference to the timing chart of FIG. 4 along the flowchart of FIG.

When an ignition switch (not shown) is turned on (ON) to start the engine, the controller 3
0 is supplied with power and the control program starts.

After the control is started, first, the controller 30 inputs a vertical acceleration (G) signal from the vertical G sensor 10 and sets a large bump control condition (see FIG. 1) in which the magnitude of the vertical acceleration exceeds a predetermined value for a predetermined time. 5) (steps S101 and S102). If the determination result in step S102 is negative, the controller 30 proceeds to step S10.
7, a soft mode control signal for setting a soft mode is output to the first to fourth damping force switching actuators 40, 41, 42, and 43, and the suspension damper 41 is output.
, 42, 43, and 44 are all set to the soft mode.
(At this time, if a timer (not shown) is not reset, it is reset.) The mode of the suspension dampers 41, 42, 43, and 44 is similarly switched and set by the controller 30 by the damping force switching actuator. Since this is performed by outputting a predetermined control signal to 40, 41, 42, and 43, in the following description, simply "..."
… Switch to mode ”or“ …… Set to mode ”.

On the other hand, if the result of the determination in step S102 is affirmative, that is, if the large bump control condition has occurred, the controller 30 causes the left and right front wheel suspension dampers 41, as shown in FIG. , 42
Is switched to the hard mode, the operation of a timer (not shown) is started at the same time (step S103). Thereby, vibration on the front wheel side is suppressed. Then, the controller 30 waits for a set time T (which will be described later) determined based on a predetermined function using the vehicle speed as a parameter in the next step S104 to elapse. Proceed to S105. This step S10
At 5, the controller 30 also switches the suspension dampers 43 and 44 of the left and right rear wheels to the hard mode, as shown in FIG. Thereby, the swing back of the vehicle is suppressed, and the vehicle is stabilized.

Here, the set time T will be described. In the present embodiment, the set time T is determined by a function of the following equation using the vehicle speed as a parameter.

T = wheel base L / vehicle speed V of the vehicle

That is, the time T is a time required for the front wheel to ride on a large projection road surface or the like and for the rear wheel to get over the projection.
As a result, the rear-wheel-side suspension dampers 43 and 44 are switched to the hard mode immediately after the rear wheel passes over the projection without being affected by the vehicle speed.

After the processing in step S105, the controller 30 proceeds to step S1 in step S106.
After waiting for a predetermined time t (this time t is a time long enough to stop the change in the vehicle height due to overrunning of the protrusion) from the occurrence of the large bump control condition in 02, this time t
After the passage of time, suspension dampers 41, 4 for the left and right front and rear wheels
2, 43 and 44 are simultaneously switched to the soft mode, and at the same time, a timer (not shown) is reset (step S1).
07). Thereby, the state returns to the state before the large bump control. Then, thereafter, the process returns to step S101, and thereafter, the above control operation is repeated.

According to the above-described embodiment, the controller 3 is activated immediately after a large bump control condition occurs during running.
According to 0, dampers 41, 42 for suspension of front left and right wheels
Is switched to the hard mode, and the suspension dampers 43 and 44 for the left and right rear wheels are also mounted on the wheel base L of the vehicle.
After the soft mode is maintained for a time T calculated from the ratio T = L / V of (m) and the vehicle speed V (m / s), the hard mode is set (see FIG. 3). For this reason, the front-wheel-side suspension dampers 41 and 42 are set to the hard mode immediately after the front wheel passes over the large projection, so that the front-wheel side is stabilized, and the time from when the front wheel climbs over the projection to when the rear wheel climbs over the projection. Since the rear suspension dampers 43 and 44 are kept in the soft mode by T and immediately set to the hard mode, the suspension on the rear wheel side is immediately performed as soon as the rear wheel passes over the projection without being affected by the vehicle speed. The dampers 43 and 44 are set to hardware. Therefore, the sense of thrust when riding on the rear wheel in the large bump control, which has been a problem in the past, is reduced, the riding comfort is improved, and the swinging of the vehicle is almost certainly prevented, and a large fluctuation in the vehicle height can be suppressed. .

[0021]

As described above, according to the present invention,
Due to the damping force switching control means, the damper for the front wheel suspension is set to the hard mode as soon as the front wheel gets over the large projection road surface, etc. Since the soft mode is maintained during the predetermined set time until the hard mode is immediately set, the front wheel side is stabilized after riding on the large protrusion, and the above set time is determined in consideration of the vehicle speed, so As soon as the rear wheel gets over the projection without being affected by the vehicle speed, the suspension damper on the rear wheel side is set hard. Therefore, it is possible to reduce the feeling of thrust when riding on the rear wheel, which has been a problem in the past, and it is possible to improve the riding comfort in such a point, and at the same time, it is possible to almost certainly prevent the vehicle from turning back, As a result, it is possible to provide an unprecedented excellent large-bump control method for an electronically-controlled suspension that can suppress a large variation in vehicle height.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an electronically controlled suspension for implementing a large bump control system according to the present invention.

FIG. 2 is an explanatory view showing a vehicle equipped with the electronically controlled suspension of the embodiment of FIG. 1;

FIG. 3 is a flowchart showing a control program of the suspension controller of FIG. 1;

FIG. 4 is a timing chart showing mode switching of suspension dampers for front and rear wheels corresponding to the flow of FIG. 3;

FIG. 5 is a diagram for explaining conventional large bump control.

[Explanation of symbols]

Reference Signs List 1 vehicle 41 to 44 suspension damper 10 vertical acceleration sensor as vertical acceleration measuring means 20 vehicle speed sensor as vehicle speed measuring means 30 suspension controller as damping force switching control means 40 first damping as right front wheel damping force switching means Force switching actuator 41 Second damping force switching actuator as left front wheel damping force switching means 42 Third damping force switching actuator as right rear wheel damping force switching means 43 Second damping force switching means as left rear wheel damping force switching means 4 damping force switching actuator

Claims (1)

(57) [Claims] 1. A vertical acceleration measuring means for measuring a vertical acceleration applied to a vehicle body when a vehicle is running, a vehicle speed measuring means for measuring a running speed of the vehicle, and a predetermined speed based on each output signal from the both measuring means. A damping force switching control means for performing calculations and switching between modes of four suspension dampers respectively mounted on the left, right and front and rear wheels of the vehicle to a hard or soft mode via respective damping force switching means. In the control suspension, when the damping force switching control unit receives an output signal of the vertical acceleration measuring unit and determines that a large bump control condition in which a state where the value of the vertical acceleration is equal to or more than a certain value continues for a certain time or more has occurred. Switch the dampers for suspension of the left and right front wheels to hard mode, and from this switch, a predetermined function with the vehicle speed as a parameter The suspension dampers for the left and right rear wheels are switched to the hard mode after a lapse of a set time determined based on the above, and the suspension dampers for the four wheels are simultaneously switched to the soft mode after a lapse of a predetermined time from the occurrence of the large bump control condition. Large bump control method of electronic control suspension.