JP2001039138A - Suspension control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce radio noise by detecting the running condition of a vehicle, and setting the amplitude of dither current forming a command current corresponding to a desired damping characteristic and an applied current to a solenoid to a smaller value when the vehicle is substantially in the stop state as the detection result. SOLUTION: According to applied current to a solenoid 2 of a proportional solenoid valve 5 from a battery 1, a spool 3 is vertically displaced to adjust the passing amount of oil liquid 4 and change the damping characteristic of a shock absorber 6. The detection output of an acceleration sensor 7 is input to a controller 8 to compute a command current for obtaining desired damping force and dither current by a CPU 12, and then supply current where dither current is superposed on the command current is applied to the solenoid 2. As a result, when the vehicle is substantially in the stop state, the amplitude of dither current is set to a smaller value by a dither amplitude adjusting circuit 13 of the controller 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a suspension control device used for an automobile or the like.

[0002]

2. Description of the Related Art As an example of a conventional suspension control device, Japanese Patent Application Laid-Open No. 10-166828 proposed by the present inventor has been proposed.
There is one shown in Japanese Patent Publication No. This suspension control device makes the dither vibration applied to the current control type actuator variable for each command current, manages the fluctuation of the damping force caused by the dither vibration, and prevents the generation of sound and vibration.

[0003]

Incidentally, the dither vibration generally has a frequency of several hundred Hz, and the power supply line and the solenoid line may fluctuate electrically due to the current fluctuation. The electric fluctuation is radio, TV
This may cause noise (radio noise) to equipment that uses radio waves, such as radio waves, and the occupant may feel uncomfortable. The noise becomes more conspicuous as the noise of the vehicle itself is smaller, and becomes particularly remarkable when the vehicle speed is low such as when the vehicle is stopped. In the above-described conventional technology, it is possible to prevent the fluctuation of the damping force due to the dither, but since the dither is added regardless of the vehicle speed, the radio noise during a stop may become relatively large.

The present invention has been made in view of the above circumstances, and has as its object to provide a suspension control device capable of reducing radio noise.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a proportional solenoid valve having a solenoid and a movable body which is displaced in accordance with an electric current supplied to the solenoid, and which expands and contracts between a vehicle body and an axle. A damping characteristic variable shock absorber that is freely interposed and whose damping characteristic changes according to the displacement of the movable body, and a dither that is superimposed on a command current corresponding to a desired damping characteristic and constitutes the energizing current together with the command current A dither generating means for generating current, wherein the suspension control device vibrates the movable body at a position corresponding to the command current at an amplitude corresponding to the dither current. Detecting means for setting the amplitude of the dither current to a small value when the traveling state detecting means detects that the vehicle is almost stopped. .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A suspension control device according to an embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, the suspension control device includes a solenoid 2 having one end connected to a battery (power supply) 1 and a movable body (spool) 3 which is vertically displaced in accordance with a current supplied to the solenoid 2. Proportional solenoid valve 5 that adjusts the amount of passage of oil liquid 4 in accordance with the displacement of
And a variable damping characteristic type interposed between a vehicle body (not shown) and an axle (not shown) so as to be extendable and contractable and operate with a damping force of a magnitude corresponding to the supply current and, consequently, the displacement of the movable body 3. A shock absorber 6, an acceleration sensor 7 for detecting the vertical acceleration (vibration) of the vehicle body, a controller 8 connected to the other end of the solenoid 2, and a vehicle speed sensor for detecting the vehicle speed (running state of the vehicle) State detecting means) 20
, And is roughly composed of

The controller 8 has a transistor 10 and a shunt resistor 11 interposed in this order between the other end of the solenoid 2 and the ground 9 (earth), and controls the transistor 10 to control the solenoid 2 The supply current (conduction current) is made to flow. In this case, the supply current is configured by superposing the dither current shown in FIG. 4 on the command current corresponding to the desired damping force (damping characteristic), and by positioning the movable body 3 at a portion corresponding to the command current. , A desired damping force is generated in the shock absorber 6 (proportional solenoid valve 5), and the movable body 3 is finely vibrated (dithered) in accordance with the dither current at the position. Try to improve the responsiveness of the change. As shown in FIG. 4, the dither current has a high frequency (for example, 32 KH) at a dither frequency (for example, 100 Hz) and a dither fundamental component having an amplitude (dither amplitude) of a predetermined (reference) magnitude.
The component (z) (high-frequency component) is superimposed.
By superimposing a command current (not shown) on the dither current, the supply current (conduction current) supplied to the solenoid 2 is configured as described above.

The controller 8 further includes an acceleration sensor 7
CPU (dither generation means) 12 for obtaining a command current for obtaining a desired damping force and a dither current (dither amplitude command) having a predetermined amplitude in accordance with the detection signal of
A dither amplitude adjustment circuit 13 for adjusting the amplitude of the dither current output from the output circuit 12; an addition circuit 14 for adding the output signal of the dither amplitude adjustment circuit 13 and the command current;
The terminal voltage value of the shunt resistor 11 is fed back to the output value of 4 to obtain a transistor control signal for controlling the transistor 10, the amplitude of the dither current is adjusted, and the transistor control signal is corrected according to the adjustment result. A current correction circuit 15 and a PWM conversion circuit 21 for obtaining a PWM signal by superimposing a high-frequency component of, for example, 32 KHz are provided. By controlling the transistor 10 with the PWM signal, a dither current is superimposed on the command current, and The supply current whose current amplitude is adjusted is caused to flow through the solenoid 2. The dither amplitude adjustment circuit 13
It stores command current-dither amplitude data (map) (not shown) obtained in advance by experiments, numerical calculations, and the like.
Based on this map, the amplitude of the dither current is preliminarily set before the processing of the current correction circuit 15.

The operation of the suspension control device configured as described above is controlled by the dither amplitude adjustment circuit 13 and the CPU 1.
2 and FIG. 3 together with the content of the arithmetic processing of the controller 8 including the adder circuit 14, the current correction circuit 15, and the like will be described below. First, initialization is performed (step S1), and it is determined whether or not the control cycle has elapsed until YES is determined (step S2). Step S2
If YES is determined in step S3, the solenoid 2 is driven based on the signal calculated in the previous control cycle (step S3). Subsequent to step S3, members and parts other than the solenoid 2 (LED
Etc.) (step S4).

In the next step S5, the detection value of the acceleration sensor 7 and the detection value (vehicle speed) of the vehicle speed sensor 20 are read.
In the following step S6, a dither current amplitude adjustment process (subroutine) is performed, and the dither current amplitude is adjusted as described later. Subsequent to step S6, based on the processing contents of the dither current amplitude adjustment subroutine of step S6, a control calculation for obtaining a command value corresponding to the current supplied to the solenoid 2 is performed (step S7), and the process returns to step S2. .

The dither current amplitude adjustment subroutine of step S6 will be described with reference to FIG. First, the vehicle speed sensor 20
Is a threshold value (set value) i set in advance.
It is determined whether or not the following is true (step S11). If YES is determined in the step S11, the amplitude of the dither current (the dither amplitude) is reduced (step S12), and this subroutine is ended to return to the main routine of FIG. If NO is determined in step S11, the amplitude of the dither current d is increased (step S13), the subroutine ends, and the process returns to the main routine of FIG. In step S12, the dither amplitude is reduced to about one fifth of the reference amplitude.

When the vehicle is stopped or traveling at or below the set value i (almost stopped (10 km / h or less)), as described above, the vehicle speed sensor 20
Is determined to be less than or equal to the set value i (determined to be YES in step S11), and the amplitude of the dither current (dither amplitude) is reduced (step S12). For this reason, the fluctuation of the supply current (conduction current) flowing through the solenoid 2 is reduced, and the radio noise can be reduced. According to the prior art, the radio noise is particularly conspicuous during low vehicle speeds or when the vehicle is stopped, where the noise of the vehicle itself is small. However, according to the present embodiment, the vehicle travels when the vehicle is stopped or the vehicle travels at or below the set value i. In this case, the radio noise can be reduced as described above, so that a radio program or the like can be satisfactorily heard even at a low vehicle speed or while the vehicle is stopped, without being affected by dither vibration.

In the above embodiment, the case where the set value i to be compared with the detected value (vehicle speed) of the vehicle speed sensor 20 is one is exemplified. However, instead of this, two or more set values are used. The configuration may be such that the detection value (vehicle speed) of the vehicle speed sensor 20 is used for comparison.

In the above embodiment, the case where the traveling state detecting means is the vehicle speed sensor 20 is taken as an example. However, instead of this, a brake switch, a throttle sensor, an engine rotation sensor (tachometer), a side brake, an automatic transmission A parking switch and a door (back door) switch may be used. These detecting means determine that the vehicle is stopped in the following cases. That is, when the brake switch has a long brake-on time (in a state where the brake is depressed), the throttle sensor has a long throttle-off time (in a state where the accelerator pedal is not depressed), and the engine rotation sensor (tachometer) has an idle (low-speed). ) Lasts for a long time when the side brake is turned on for the side brake, when the parking switch is turned on for the AT car parking switch, and when the door switch is turned on (door closed) for the door (back door) switch, respectively. It is determined that the vehicle has stopped.

[0015]

As described above in detail, according to the present invention, when the traveling state detecting means detects that the vehicle is almost stopped, the amplitude of the dither current is set to a small value. Fluctuations in the current flow are reduced and radio noise is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a suspension control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the contents of arithmetic processing by the controller shown in FIG. 1;

FIG. 3 is a flowchart showing a dither current amplitude adjustment subroutine of FIG. 2;

FIG. 4 is a waveform diagram schematically showing a dither current used in the suspension control device of FIG.

[Explanation of symbols]

 2 Solenoid 3 Movable body 5 Proportional solenoid valve 6 Shock absorber 8 Controller 12 CPU 13 Dither current adjustment circuit

Claims (1)

[Claims] 1. A proportional solenoid valve having a solenoid and a movable body which is displaced in accordance with a current supplied to the solenoid, and a damping characteristic which is interposed between a vehicle body and an axle so as to be extendable and contractible and which is movable in accordance with the displacement of the movable body. And a dither generating means that generates a dither current that is superimposed on a command current corresponding to a desired damping characteristic and that forms the energizing current together with the command current. A suspension control device that vibrates at a position corresponding to the command current with an amplitude corresponding to the dither current, wherein a running state detecting unit that detects a running state of the vehicle is provided, and the running state detecting unit substantially stops the vehicle. Wherein the amplitude of the dither current is set to a small value when it is detected that the suspension state has occurred.