JP3713674B2 - Suspension control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a suspension control device used for an automobile or the like.
[0002]
[Prior art]
As an example of a conventional suspension control device, there is a device previously proposed by the applicant of the present application in Japanese Patent Application No. 1-5135 (Japanese Patent Laid-Open No. 2-96302). This device includes a solenoid having one end connected to a power source, a proportional solenoid valve having a movable body that is displaced in response to an energization current to the solenoid, and a vehicle body and an axle. A suspension body that adjusts the vehicle height according to the displacement, a transistor and a shunt resistor that are sequentially inserted between the other end of the solenoid and the grounding part, and compares the target voltage with the terminal voltage of the shunt resistor. The transistor is turned on when the target voltage is higher than the terminal voltage and turned off when the target voltage is low, so that a dither current having a predetermined amplitude is included in the energization current, thereby suppressing the heat generation of the transistor. Yes.
[0003]
[Problems to be solved by the invention]
By the way, as shown in FIG. 7, the proportional solenoid valve is substantially proportional to the force generated with respect to the command current, but is not proportional when the current value is low, and is generated in comparison with the rate of increase in current. The increasing rate of the force to be applied (thrust acting on the movable body) is small.
For this reason, if the amplitude of the dither current is a constant value (D ₁ ), the thrust acting on the movable body becomes small when the current value is small, so that the movable body is finely (dithered) appropriately (large thrust). However, there is a possibility that the response of the damping force change is lowered, the hysteresis in the current-damping force characteristic is increased, and the ride comfort is deteriorated.
[0004]
Incidentally, F ₁ say necessary force F ₁ (where the dither current when the command current is small (for example, current I ₁₎ as shown in FIG. 7 is a thrust can be appropriately finely vibrating the movable body .) When setting the dither current having a predetermined amplitude D ₁ so as to obtain an area command current is large (e.g., current I ₂₎ the large force F ₂ generated by the dither current equal predetermined amplitude D ₁ (F _2> F ₁ ), the movable body may vibrate greatly, and the proportional solenoid valve may generate a loud sound or vibration.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a suspension control device that improves the response of the damping force change and can suppress the generation of loud noise and vibration of the proportional solenoid valve. To do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a proportional solenoid valve having a solenoid and a movable body that is displaced in response to a current supplied to the solenoid, and a movable body that is telescopically interposed between a vehicle body and an axle. A shock absorber of variable damping force type that generates a damping force according to the displacement of the motor, and a dither generating means for generating a dither current that constitutes the energization current together with the command current superimposed on the command current corresponding to the desired damping force A suspension control device that vibrates the movable body at a position corresponding to the command current, with an amplitude and a period corresponding to the dither current, so that a change range of a thrust that is changed by the dither current is constant. Further, a dither amplitude adjusting means for adjusting the amplitude of the dither current according to the magnitude of the command current is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a suspension control apparatus according to an embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the suspension control device has a solenoid 2 connected at one end to a battery (power source) 1 and a movable body (spool) 3 that is displaced in accordance with an energization current to the solenoid 2. Accordingly, a proportional solenoid valve 5 that adjusts the passage amount of the oil liquid 4 and a vehicle body (not shown) and an axle (not shown) are interposed between the energizing current and the displacement of the movable body 3. The shock absorber 6 is a variable damping force type for generating a damping force, an acceleration sensor 7 for detecting the vertical acceleration of the vehicle body, and a controller 8 connected to the other end of the solenoid 2. .
[0008]
The controller 8 includes a transistor 10 and a shunt resistor 11 that are interposed in this order between the other end of the solenoid 2 and the ground 9. The controller 8 turns on and off the transistor 10 to pass an energization current through the solenoid 2. I am doing so. In this case, as will be described later, the energizing current is constituted by a command current corresponding to the average value of the energizing current and a dither current superimposed on the command current, and the movable body 3 is provided in a portion corresponding to the command current. Positioning the shock absorber 6 to generate a desired damping force and causing the movable body 3 to vibrate (dither) in response to the dither current at the position, thereby responding to a change in the damping force of the movable body 3 and eventually the shock absorber 6. I try to improve the sex.
[0009]
The controller 8 further includes a 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 a detection signal of the acceleration sensor 7. The dither amplitude adjusting circuit (dither amplitude adjusting means) 13 for adjusting the amplitude (dither amplitude command) of the dither current output from the CPU 12 as described later, and the addition for adding the output signal and the command current of the dither amplitude adjusting circuit 13 A circuit 14; and a current feedback circuit 15 that obtains a transistor control signal by feeding back a terminal voltage value (detected value) of the shunt resistor 11 to an output value of the adder circuit 14, and controls the transistor 10 using the transistor control signal. By doing so, the energization current in which the dither current is superimposed on the command current is allowed to flow to the solenoid 2. .
[0010]
The dither amplitude adjustment circuit 13 stores command current-dither amplitude data (map) as shown in FIG. The data in FIG. 4 is a curve with the command current on the horizontal axis and the dither current amplitude (dither amplitude) on the vertical axis, and the energizing current consisting of the command current and dither amplitude on this curve is supplied to the solenoid 2. This shows that the force acting on the movable body 3 due to the dither current becomes constant. As is apparent from FIG. 4, in order to make the force acting on the movable body 3 constant by the dither current, when the command current is small, the dither amplitude is increased, and when the command current is greater than or equal to a predetermined magnitude. In addition, the dither amplitude may be made constant. Then, the dither amplitude adjustment circuit 13 uses the command current-dither amplitude data of FIG. 4 as described later, cooperates with the CPU 12, the adder circuit 14, and the current feedback circuit 15 to perform arithmetic processing as follows. The amplitude of the current is adjusted.
[0011]
Here, the processing contents of the dither amplitude adjusting circuit 13, the CPU 12, the adding circuit 14, and the current feedback circuit 15 will be described with reference to FIGS.
First, initialization is performed (step S1), and the determination as to whether or not the control period t _{ms has} elapsed is performed until it is determined to be YES (step S2). If YES is determined in step S2, the solenoid 2 is driven based on the signal calculated in the previous control cycle (step S3).
Subsequent to step S3, the information is output to members and portions (LEDs, etc.) other than the solenoid 2 (step S4).
[0012]
In the next step S5, the detection value of the acceleration sensor 7 is input. In the following step S6, based on the detected value of the acceleration sensor 7 read in step S5, the damping force necessary for damping the vehicle body and the command current necessary for generating this damping force (average value of the energized current) And the dither current. In the subsequent step S7, the dither amplitude adjustment circuit 13 performs the dither current amplitude correction process (subroutine).
[0013]
The dither current amplitude correction subroutine will be described with reference to FIG.
First, the amplitude of the dither current is calculated from the map of FIG. 4 (step S10). In the next step S11, I = (dither current) / 2 is calculated, and the average value of the dither current is obtained. Subsequently, in step S12, the following equation (1) is calculated, and the output current (energization current) I _OUT (the dither amplitude centered on the command current is superimposed by adding the average value of the dither current to the command current. Ask).
[0014]
I _OUT = (command current value) + I (1)
[0015]
Then, in the next cycle step S3, the output current (energization current) I _OUT is output, and the transistor 10 is turned on and off so that the average value of the output current (energization current) I _OUT finally output becomes the command current. An output current (energization current) I _OUT as shown in FIG. 5 is obtained.
[0016]
In the suspension control apparatus configured as described above, the process of step S10 is performed, and as shown in FIG. 5 [that is, the change width of the thrust that changes due to the dither current is constant (for example, F ₁ '= F ₂ as described later ). consisting] as described above, when the command current is small (I _1), the dither current command current is large (I ₂₎ greater amplitude D ₁ than the amplitude D ₂ of the case _{'(D 1'> D 2} ) To correct. Therefore, when the command current is small (I ₁ ), the force F ₁ acting on the movable body 3 is large (the same magnitude as the force F ₂ when the command current is large (I ₂ ), that is, F ₁ ′ = F ₂ ), the movable body 3 can be easily displaced, and the responsiveness can be improved.
[0017]
When the command current value is large (I ₂ ), the dither current amplitude D ₂ (D ₂ <D ₁ ′) is made smaller than when the command current value is small (I ₁ ). 3 is suppressed from vibrating greatly, and no unnecessary sound is generated or the proportional solenoid valve 5 does not vibrate.
[0018]
【The invention's effect】
Since the present invention is a suspension control device configured as described above, when the command current is small, the amplitude is corrected to be larger than the amplitude when the command current is large, and when the command current is small. Since the force for applying the movable body can be increased (for example, to the same magnitude as the force when the command current is large), the movable body can be easily displaced and the response can be improved. At this time, when the command current is large, the amplitude of the dither current is smaller than when the command current is small, so that the movable body is prevented from greatly vibrating, generating unnecessary sound, It is possible to prevent the solenoid valve from vibrating.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a suspension control apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing the calculation processing contents of a dither amplitude adjusting circuit, a CPU, an adding circuit, and a current feedback circuit in FIG. 1;
FIG. 3 is a flowchart showing a dither current amplitude correction processing subroutine of the flowchart of FIG. 2;
FIG. 4 is a diagram showing amplitude data of a dither current with respect to a command current in which a force acting on the movable body is constant.
FIG. 5 is a diagram for explaining the operation of the apparatus shown in FIG. 1;
6 is a diagram schematically showing a command current and a dither current of an energization current of the apparatus of FIG. 1. FIG.
FIG. 7 is a diagram schematically showing a problem of a conventional technique.
[Explanation of symbols]
2 Solenoid 3 Movable body 5 Proportional solenoid valve 6 Shock absorber 8 Controller 12 CPU
13 Dither amplitude adjustment circuit

Claims (1)

A proportional solenoid valve having a solenoid and a movable body that is displaced in accordance with an energization current to the solenoid;
A shock absorber of variable damping force type that is telescopically interposed between the vehicle body and the axle and generates a damping force according to the displacement of the movable body;
Dither generating means for generating a dither current that constitutes the energization current together with the command current superimposed on a command current corresponding to a desired damping force, and at the position corresponding to the command current, the dither current at the position corresponding to the command current A suspension control device that vibrates with an amplitude and period according to
A suspension control apparatus, comprising: a dither amplitude adjusting unit that adjusts the amplitude of the dither current in accordance with the magnitude of the command current so that a change range of a thrust that is changed by the dither current is constant .

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