JP2949402B2 - Vehicle suspension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control apparatus for a vehicle, and more particularly, to a suspension control apparatus for a vehicle in which a mode of a suspension characteristic is manually switched between hardware and software.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a sub-tank 86 communicating with the inside of an air spring 83 via a pipe 85 is provided, and a solenoid valve 87 as opening / closing means is provided in the pipe 85,
An air suspension device that switches a spring constant by controlling opening and closing of a solenoid valve 87 according to a vehicle speed and a steering angle has been proposed. Reference numeral 84 denotes a leveling valve interposed in a communication pipe with an air reservoir tank (not shown) adjusted to a predetermined pressure.

For example, when the vehicle speed is detected and the detected vehicle speed is lower than a predetermined value, or when the vehicle speed is higher than the predetermined value and the steering angle is lower than the predetermined value, the solenoid valve 87 is automatically opened to establish communication between the air spring 83 and the inside. By integrating the sub-tank 86, the air volume inside the air spring 83 is substantially increased. In this case, since the internal pressure does not increase in response to an external force as the air volume increases, the reaction force of the air spring 83 decreases, and the spring constant decreases, so that the riding comfort can be improved.

On the other hand, means for changing the damping force of a shock absorber provided in parallel with the air spring is provided in order to prevent the body from swinging when unloading the cargo.
When the vehicle speed detected by the vehicle speed detecting means or the like is equal to or lower than a predetermined vehicle speed, it is determined that the vehicle is almost stopped and the damping force of the shock absorber is automatically increased (see Japanese Patent Application Laid-Open Publication No. H10-163,197). 61-268513).

In these suspension devices, control for switching suspension characteristics of the suspension device such as a spring constant of an air spring and a damping force of a shock absorber is performed by detecting an operating state such as a vehicle speed. The configuration is implemented in accordance with one of the following modes: an automatic mode for automatically switching according to the driving state, and a manual mode for switching and fixing the suspension characteristics to either one according to the driver's will.

[0006] Furthermore, as an example using these suspension devices, Mitsubishi Motors Technical View 1993
Year No. 5 there is an electronically controlled suspension for large buses as described on pages 97-102.

[0007]

However, in these conventional vehicle suspension control devices, a vehicle speed sensor for detecting the vehicle speed is used regardless of whether the mode switching control of the suspension hardware or software is performed in a manual mode or an automatic mode. If a failure occurs due to disconnection, etc., the desired spring characteristics cannot be obtained when the suspension hardware and software mode switching control is in the manual mode because the air spring is softly fixed and the shock absorber is hardened. .

Further, the applicant of the present invention has proposed that, when the suspension characteristic switching control is in the manual mode, the service life of the solenoid valve for switching the spring constant of the air spring is extended,
Also, in order to improve the unloading of cargo and the getting on and off of passengers when the vehicle is almost stopped, the minimum required switching is required even when the mode switching control of the hardware and software of the suspension is in the manual mode. An application for controlling is filed earlier .

In view of the above, the present invention has been made in view of the above-mentioned conventional problems. Even if a failure of the traveling state detecting means is determined, the mode switching control of the suspension hardware and software is set to the manual mode. In this case, the state of the air spring and the shock absorber is fixed to a state corresponding to the mode switched by the mode switching means, so that the suspension state matched to the driver's will is provided as a suspension characteristic and the running state detection means fails. It is an object of the present invention to provide a vehicle suspension control device capable of ensuring ride comfort and steering stability.

[0010]

According to the present invention, at least one sprung system is provided between a sprung system and a front, rear, left and right unsprung system in a vehicle to support the sprung system. An air spring, a shock absorber provided at least one each between the sprung system and each of the unsprung systems, and whether to automatically or manually switch between the hard spring and the soft mode of the air spring and the shock absorber. Mode switching means for switching, air spring switching control means for switching the air spring to software when the energization is started, and software switching the air spring when the energization is stopped, traveling state detecting means for detecting the traveling state of the vehicle, mode switching means When the mode of the air spring and the shock absorber is manually switched to hard, When the running state detecting means detects the stop state of the vehicle, the power supply to the air spring switching control means is stopped and the air spring forcible switching means for switching the state of the air spring to software is provided. When the running state detecting means detects the stop state of the vehicle while the mode of the air spring and the shock absorber is manually switched to software, the shock absorber forcibly switches the state of the shock absorber to hardware. Switching means, the operation of the air spring forcible switching means or the shock absorber forcible switching means is performed when the failure determining means determines that the traveling state detecting means has failed. interrupted, the mode switching means in the manual mode The manual mode
And a failure fixing means for fixing the states of the air spring and the shock absorber in the state selected in (1 ).

According to the second aspect of the present invention, the traveling state detecting means is constituted by a vehicle speed sensor.

[0012]

According to the first aspect of the present invention, when the mode of the air spring and the shock absorber is manually switched to the hard mode by the mode switching means, the stop state of the vehicle is detected. The energization of the air spring switching control means, which has been started by energizing the air spring switching control means by switching the state of the air spring to software and manually switching to the hard state, is stopped. As a result, unnecessary action of the air spring switching control means can be prevented.

Further, when the mode of the air spring and the shock absorber is manually switched to software by the mode switching means, and when the stop state of the vehicle is detected, the mode is manually switched to software. In addition, the state of the shock absorber is forcibly switched to a hard state to prevent the body from shaking when unloading and loading passengers or getting on and off passengers.

Further, as an effect according to the first aspect of the present invention, when it is determined that the traveling state detecting means has failed, the stop state of the vehicle cannot be detected. interrupting the operation of the forced switching means or shock absorber force switching means, the state in the mode switching means is a manual mode, which is selected at that time, i.e.,
When the soft mode is selected, the air spring and the shock absorber are fixed softly, and when the hard mode is selected, the air spring and the shock absorber are fixed hard.

Thus, it is possible to obtain a suspension characteristic desired by the driver. According to the second aspect of the present invention, the traveling state of the vehicle can be detected by detecting the vehicle speed with the vehicle speed sensor.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an air suspension device for one wheel of a vehicle. That is, in this figure, an air spring 2 and a shock absorber 7 having a built-in damping force switching mechanism are provided between a vehicle body 20 as a sprung portion of the vehicle and a tire 1 as a unsprung portion. An air reservoir tank (not shown) for storing compressed air communicates with the air spring 2 through a supply / exhaust passage 21 provided with a leveling valve 4 for supplying and exhausting compressed air to and from the air spring 2. The inside of the air spring 2 and the sub-tank 5 are communicated with each other by a communication path 22 provided with a spring constant switching valve 40 including an electromagnetic valve as an opening / closing means for switching a spring constant.

Here, the spring constant switching valve 40 includes a spring 41
A spool (not shown) which is elastically biased in the valve opening direction by, for example, is moved in a valve closing direction against the elastic biasing force by an electromagnet 42 which is energized by energization. It is a normally open type. That is, when the power supply to the electromagnet 42 of the spring constant switching valve 40 is stopped, the spool moves in the valve opening direction by the elastic urging force of the spring 41 and the like, and the inside of the air spring 2 and the sub tank 5
The air volume inside the air spring 2 is substantially increased by integrating the air spring 2 with the air spring 2. In this case, since the internal pressure does not increase in response to an external force as the air volume is larger, the reaction force of the air spring 2 is reduced, and the spring constant is reduced, so that the riding comfort can be improved. Further, the electromagnet 42
When power is supplied to the air spring 2, the spool moves in the valve closing direction against the elastic biasing force of the spring 41 and the like, thereby cutting off the communication between the inside of the air spring 2 and the sub tank 5, thereby reducing the air volume inside the air spring 2. Substantially reduce. In this case, the air volume is reduced, and the internal pressure is increased with respect to the external force, so that the reaction force of the air spring 2 is increased, so that the spring constant is increased and the hardware becomes hard.

The shock absorber 7 is provided with an actuator 8 as a damping force switching mechanism. Further, a control unit 9 having a built-in microcomputer receives a changeover M signal from a mode changeover switch 10 described later and a vehicle speed V signal from a vehicle speed sensor 17.

The control unit 9 includes an air spring forcible switching means for forcibly switching the air spring based on the switching M signal and the vehicle speed V signal, and a shock absorber for forcibly switching the state of the shock absorber. The forcible switching means is provided by software, and the control signal output from the control unit 9 controls the opening / closing of the spring constant switching valve 40 and the switching control of the damping force of the shock absorber 7.

FIG. 2 is a detailed control block diagram. A signal output from the mode changeover switch 10 is input through a mode signal input means 31 and a signal output from the vehicle speed sensor 17 is input into a vehicle speed signal input. Control means 35 via means 32
Is input to The control signal output from the control means 35 is
The spring constant switching valve 40 is connected to the spring constant switching valve 40 via the spring constant switching valve switching signal output means 36.
Are input to the actuators 8 of the damping force switching mechanism of the shock absorber 7 through the respective switches.

Next, referring to the flow chart shown in FIG.
The switching control of the actuator 8 of the damping force switching mechanism of the shock absorber 7 will be described. For the operation related to the switching control, refer to a time chart shown in FIG. In step 1 (abbreviated as S1 in FIG. 3; the same applies hereinafter), various read signals are initialized.

In step 2, the signal M output from the mode changeover switch 10 is transmitted through the mode signal input means 31 to
A signal V output from the vehicle speed sensor 17 is input via the vehicle speed signal input means 32. In step 3, the switching position of the mode changeover switch 10 is determined based on the signal M described above, and whether the mode has been switched to the manual fixed mode of the hard mode (large spring constant) or the soft mode (small spring constant) is automatically determined. It is determined whether the mode has been switched to the auto mode for performing the switching control. If the soft mode has been selected, the process proceeds to step 4 and subsequent steps. If the hard mode has been selected, the process proceeds to step 9 and subsequent steps. If the auto mode has been selected, the process proceeds to step 14 and subsequent steps.

That is, the mode changeover switch 10 constitutes a mode changeover means. First, the case where the soft mode is selected in step 3 will be described. For the operation when this mode is selected, refer to the time chart for the soft mode described in the right column in the time chart of FIG. In step 4, in order to improve the riding comfort, the power supply to the electromagnet 42 is stopped, the spring constant switching valve 40 is opened, and the spring constant is switched to a small value.
The air spring 2 is switched softly (see FIG. 4C).

In step 5, it is determined whether or not there is a failure related to the vehicle speed sensor 17. Here, since the vehicle speed sensor 17 can detect the running state , it functions as a running state detecting means. Here, it is determined whether or not there is a failure related to the vehicle speed sensor 17, for example, when the parking brake is not applied (OFF) and the vertical acceleration or the lateral acceleration is equal to or more than a predetermined value. 17
If the output from the vehicle speed sensor 17 is not output from the vehicle speed sensor 17, the vehicle speed sensor 17 is out of order even though the vehicle is traveling, or the harness of the vehicle speed sensor 17 is disconnected. Otherwise, it is determined that there is a failure related to the vehicle speed sensor 17.

That is, step 5 has a function as a failure determining means for determining a failure of the traveling state detecting means. If it is determined in step 5 that there is no failure related to the vehicle speed sensor 17, the process proceeds to step 6, where the vehicle speed signal read from the vehicle speed sensor 17 is determined, and the vehicle speed becomes 0.
, That is, whether the vehicle is running. If it is determined that the vehicle speed is not 0, the process proceeds to step 8, and it is determined that the soft mode has been manually selected by the driver who intends to soften the suspension characteristics while the vehicle is running. The actuator 8 of the damping force switching mechanism of the absorber 7 is switched and controlled to soften the shock absorber 7 (small damping force).
(See FIGS. 4B and 4D). As a result, the suspension characteristics are softened, and the riding comfort is improved.

On the other hand, if it is determined in step 6 that the vehicle speed is 0, the process proceeds to step 7, and even if the vehicle is in a stopped state and the driver intends to soften the suspension characteristics. Since it is not necessary to improve the riding comfort, the actuator 8 of the damping force switching mechanism of the shock absorber 7 is switch-controlled to switch the shock absorber 7 to hard (large damping force) (FIG. 4).
(See (b, d)).

That is, steps 6 to 8 have the function of the shock absorber forcible switching means. Step 5
If it is determined that there is a failure related to the vehicle speed sensor 17 in step (1), the process proceeds to step 8. In other words, if there is a failure related to the vehicle speed sensor 17, it is impossible to detect the vehicle speed as well as the vehicle stopped state. That is, the shock absorber 7 is fixed in a state desired by the driver.

Next, the case where the hard mode is selected in step 3 will be described. For the operation when this mode is selected, refer to the time chart for the hard mode described in the left column in the time chart of FIG. In step 9, the actuator 8 of the damping force switching mechanism of the shock absorber 7 is switch-controlled to switch the shock absorber 7 to hard (high damping force) (see FIG. 4D).

In step 10, it is determined whether or not there is a failure related to the vehicle speed sensor 17. That is, step 10 also functions as a failure determination unit that determines a failure of the traveling state detection unit. In step 10, the vehicle speed sensor
If it is determined that there is no failure related to 17, step 11
Then, the vehicle speed signal read from the vehicle speed sensor 17 is determined, and it is determined whether or not the vehicle speed is 0, that is, whether or not the vehicle is running. When it is determined that the vehicle speed is not 0, the process proceeds to step 13, and it is determined that the hard mode is manually selected with the intention that the vehicle is running and the driver intends to harden the suspension characteristics.
By energizing the electromagnet 42, the spring constant switching valve 40 is closed, the spring constant is switched to a large value, and the suspension characteristics are hardened (see FIGS. 4B and 4C).

On the other hand, if it is determined in step 11 that the vehicle speed is 0, the process proceeds to step 12, and even if the vehicle is in a stopped state and the driver intends to harden the suspension characteristics, Since it is not necessary to improve the steering stability, the power supply to the electromagnet 42 is stopped, the spring constant switching valve 40 is opened, and the spring constant is switched to a small value (FIG. 4).
(See (b, c)).

That is, the spring constant switching valve 40 and the steps 11 to
Reference numeral 13 denotes an air spring switching control means, and
Reference numeral 5 has a function of a forced switching device at the time of stop. So,
When the hard mode is manually selected, the energization of the spring constant switching valve 40, which is the air spring switching control means that has been started to be energized, is stopped, and unnecessary exciting current is supplied to the spring constant switching valve 40. It is possible to prevent continuous supply.

Therefore, even when the vehicle is stopped and the hard mode is maintained for a long time when the mode changeover switch 10 is manually set to the hard mode, the electromagnet 42 of the spring constant changeover valve 40 is kept long. It is possible to prevent the power from being supplied for a long time, thereby preventing the supply voltage of the battery from being lowered, and also extending the life of the spring constant switching valve 40.

On the other hand, in step 10, the vehicle speed sensor 17
If it is determined that there is a failure according to (1), the process proceeds to step S13. That is, when there is a failure related to the vehicle speed sensor 17,
It is impossible to detect the vehicle speed as well as the stop state of the vehicle.
The spring constant switching valve 40 is fixed in the hard mode selected in, that is, in a state desired by the driver.

Next, the case where the auto mode is selected in step 3 will be described. In step 14, it is determined whether or not there is a failure related to the vehicle speed sensor 17. That is, step 14 also functions as a failure determination unit that determines a failure of the traveling state detection unit. Step 14
When it is determined that there is no failure related to the vehicle speed sensor 17, the process proceeds to step 15, and the suspension characteristics are automatically controlled based on the vehicle speed signal V read from the vehicle speed sensor 17, the steering angle, and the like.

On the other hand, at step 14, the vehicle speed sensor 17
If it is determined that there is a failure related to the vehicle speed, it is impossible to detect the vehicle speed, so in step 16, the spring constant is switched to a small value to balance the ride comfort and running stability. The characteristic is made soft, and in step 17, the shock absorber 7 is switched to hard.

Therefore, even when the vehicle speed sensor 17 fails, if the mode changeover switch 10 is manually changed, it is possible to obtain the driver's desired suspension characteristics. Even when the mode is automatically switched, the suspension characteristics are changed so as to balance the riding comfort and the running stability.

[0037]

As described above, according to the first aspect of the present invention, when the traveling state detecting means is normal, the air spring switching control means is extended when the vehicle stopped state is detected. It is possible to prevent the continuous operation of the shock absorber for a long time, or to improve the merchantability by changing the state of the shock absorber to a hard state, thereby improving the getting on and off of passengers. Further, even when a failure occurs in the traveling state detection means, if the mode switching means is manually switched, it becomes possible to obtain a desired suspension characteristic of the driver, and the failure in the traveling state detection means becomes possible. When this occurs, there is an effect that it is possible to ensure the minimum suspension characteristics that match the driver's will.

Further, according to the second aspect of the present invention, by detecting the vehicle speed by the vehicle speed sensor, it is possible to easily detect the traveling state of the vehicle, and there is no increase in cost.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a control system diagram of the embodiment.

FIG. 3 is a flowchart illustrating control contents of the embodiment.

FIG. 4 is a time chart for explaining a control operation of the embodiment.

FIG. 5 is a system configuration diagram of an example of a conventional vehicle air suspension device.

[Explanation of symbols]

 Reference Signs List 1 tire 2 air spring 4 leveling valve 5 sub tank 7 shock absorber 8 actuator 9 control unit 17 vehicle speed sensor 40 spring constant switching valve

Claims (2)

(57) [Claims] An air spring provided between the sprung system and each of the front, rear, left and right unsprung systems for supporting the sprung system; and the sprung system and the unsprung systems. A shock absorber provided at least one each between the air spring and the hard of the air spring and the shock absorber;
Mode switching means for switching whether to perform software mode switching automatically or manually, and switching the air spring to hardware by starting energization,
Air spring switching control means for switching the air spring to software by stopping power supply, traveling state detecting means for detecting a traveling state of the vehicle, and mode of the air spring and the shock absorber manually switched to hardware by mode switching means. When the running state detecting means detects that the vehicle is stopped, the running state detecting means stops energizing the air spring switching control means and switches the state of the air springs to software. When the mode of the air spring and the shock absorber is manually and softly switched by the mode switching means, and when the stop state of the vehicle is detected by the traveling state detection means, the state of the shock absorber is hardened. Shock absorber forcible switching means to switch to A vehicle suspension control device comprising: a failure determination unit that determines a failure of the traveling state detection unit; and a forcing the air spring when the failure determination unit determines a failure of the traveling state detection unit. If the operation of the switching means or the shock absorber forced switching means is interrupted and the mode switching means is in the manual mode, the manual mode
And a failure fixing means for fixing the states of the air spring and the shock absorber in the state selected in (1) . 2. The vehicle suspension control device according to claim 1, wherein the traveling state detecting means is a vehicle speed sensor.