JPH02234821A - Suspension device - Google Patents

Abstract

PURPOSE:To detect deterioration or breakage of an elastic member, which forms part of a suspension device, by sensing strains in this elastic member. CONSTITUTION:The axle 2 for a wheel 1 is coupled with an upper arm 4 and a lower arm 5 through a knuckle 3. The top of an elastic member 7 having resilience in the vertical direction is borne by the car body 6 in the form of a cantilever. The bottom of this elastic member 7 is coupled rotatably with the middle of the lower arm 5. A plurality of strain sensing means 91, 92 are installed in places on the elastic member 7. Deterioration or breakage of the elastic member 7 is sensed on the basis of sensing signals given by the strain sensing means-i.e., through comparison of the actual strain measurement with the corresponding theoretical strain value at any point, which is obtained presumaptively from the actual strain measurement at a certain point as reference.

Description

[Detailed Description of the Invention] [Field of Industrial Application] Motoaki has developed a system for detecting deterioration or damage of the elastic member from strain at a plurality of locations regarding a suspension in which a part of the suspension component is made of an elastic member. It is something. [Prior Art] In Japanese Patent Application No. 63-94074, the present applicant proposed a method in which a strain detection means is provided in an elastic member constituting a part of a suspension component, and a change in stress based on the strain of the elastic member is determined. proposed to detect the load applied to the suspension or the height of the vehicle. [Problems to be Solved by the Invention] Incidentally, from the viewpoint of controlling the motion state of the vehicle and the suspension, it would be useful to detect deterioration of the elastic member over time, damage caused by some external force, etc. in terms of countermeasures. becomes.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a suspension device that can detect deterioration or damage of an elastic member that constitutes a part of a suspension component based on strain at a plurality of locations.

[A Thousand Steps to Solve the Problems] In order to achieve the above-mentioned problems, the present invention comprises a suspension component that partially includes an elastic member, and includes a plurality of strain detection means for detecting strain in the elastic member. The method is characterized in that deterioration or damage of the elastic member is detected based on the strain.

Specifically, at least one of the strain detecting means is provided at a portion of the elastic member that has a different rate of deterioration than the other strain detecting means or a portion that is likely to be damaged.

Then, a theoretical value of distortion at another point estimated from the actual measurement value of distortion at a certain point is compared with the actual measurement value of distortion at that other point.

Incidentally, the theoretical value of the distortion is obtained by either data map processing or arithmetic processing. [Action] Based on the strains at multiple locations on the elastic member obtained from multiple strain detection means, that is, the theoretical value of the strain at another point estimated from the measured value of strain at a certain point, and the strain at the other point. Deterioration or damage of the elastic member is detected by comparison with the actual measured value.

In that case, if at least one strain detection means is provided in a part of the elastic member where the rate of deterioration is different from that of the other strain detection means, or in a part where there is a possibility of damage, deterioration or damage can be detected effectively. I can do it.

Further, the theoretical value of distortion is obtained by data map processing and calculation processing.

[Example] Examples will be described below based on the accompanying drawings.

Figures 1 and 2 show only one side of the left and right wheels in a double wishbone type suspension, where ■ is the wheel, 2 is the axle, 3 is the knuckle, 4 is the upper arm, 5 is the lower arm, 6 is the vehicle body, and 7 is the There is an elastic member to which the present invention is applied.

In other words, the elastic member 7 is a horizontal leaf spring having an elastic force in the vertical direction, and the leaf spring 7 is supported by the vehicle body 6 in a cantilever manner.

In the example shown in Fig. 1, the lower arm 5 is rotatably connected to the middle part of the lower arm 5 with 7 leaf spring points (2), and in the example shown in Fig. 2 which does not have the lower arm 5, the lower arm 5 is rotatably connected to the lower part of the knuckle 3 with 7 leaf splinters (2). are rotatably connected.

According to such a suspension, since the wheel l side is always urged downward by the horizontal leaf spring 7 supported cantilevered on the vehicle body 6, it is possible to use a single shock absorber that does not require a coil spring, and By providing an arbitrary actuator between the vehicle body 6 and the leaf spring 7, a vehicle height adjustment function can be easily added.

In the suspension described above, as shown in the figure, a pair of strain detection means 91 and 9* are provided at different positions of the leaf spring 7, particularly at different rates of deterioration. Note that at least one is provided at a location where there is a possibility of damage due to external disturbances. The part that is likely to be damaged is likely to be near the wheels due to flying stones, etc., and the part that is likely to deteriorate is near the fulcrum.

Here, the strain detecting means 9 may be of a simple configuration such as a strain gage that detects changes in the amount of strain due to deflection of the leaf spring 7, and the number thereof may be three or more.

By the way, it is not limited to the plate-shaped leaf spring 7 of the embodiment, and even if the elastic member has any shape such as a coil shape, as long as it has a certain physical shape and stable chemical properties, it can be used in addition. The following relationship exists between the applied load (force) F and the strain ε at a specific position.

ε. =fp(F)...(1) Next, the same holds true for distortions at multiple locations. When the load is eliminated from these values, it can be seen that there is a correlation between the strain values.

ε,=f. (ε2, ε, ...) - (2) Therefore, from the actual measured values of strain at multiple locations, it is possible to estimate the value at any one of them using a relational expression such as equation (2) above. , let us now temporarily call this ε゛.

When a certain part of the elastic member deteriorates or breaks, the stress value experienced by that part and its vicinity increases, and the strain value also changes.

Therefore, in order to detect deterioration or damage in an elastic member, it is necessary to measure the strain values at multiple locations on the elastic member and repeatedly estimate the strain value at any one location from those measurements (based on the theory from equation (3) above). This can be done by comparing them with actual measured values and calculating the difference.

This is because the elastic member has a simple structure from the perspective of material mechanics, and in the case of a simple structure, it is not necessary to compare the measured strain value and the estimated strain value (theoretical value) at all multiple locations. can be detected even in one location. Now, Figure 3 shows the relationship between load and strain, and a certain load F
, is applied to an elastic member, for example, the strain ε1 at a certain point A is measured, and based on that, the strain ε'2 at another point B is estimated using a certain calculation formula. Furthermore, deterioration or damage is detected by comparing the measured value ε2 of strain at point B with the estimated value ε゛2. Conversely, a comparison based on the estimation of point A from point B can be similarly detected. In other words, as shown in Figure 4, for example, under normal conditions, there is a relationship between ε and ε2 as shown in [A], or a certain damage occurs in the elastic member, resulting in a relationship as shown in (A). case,
The theoretical value (estimated value) for ε゛ should be ε゛2, but the actual value is (2), so it is not possible to detect damage by comparing ε゜2 and ε-2. Next, we will explain the calculation formula. However, k+, kg are coefficients determined by the distance from point ■ to the strain detection position, and k,,k. By eliminating F from the above equation (4), when the leaf spring is normal in FIGS.
, ε2, and then ε゛1. When estimating the other one from ε゛2, and assuming that the difference is E, we get the following.

For example, if we assume that a point is damaged, ε''1 changes greatly, ε2 does not change much, and the difference between the actual measured value and the theoretical value (estimated value) at that time is E', , E'2 Then, ?'.＞α ...(8)
E'2〉β...(9)I
E'l -1 1>γ...(IO
) or l T:1-E+ 1 > δ...(1l
) (α, β, γ. δ are predetermined values that determine the damage detection range), it can be seen that it can be determined that the leaf spring 7 has been damaged. Damage can be detected most effectively by providing at least one strain detecting means in an elastic member at a location where the rate of deterioration is different from that of other strain detecting means or where damage is likely to occur. Recognize. Furthermore, it is possible to detect damage even if the damage location is other than point ■ (even if it is near the strain detection means 9■ side). A similar method can be used to detect deterioration. It can be seen that the accuracy level of damage/deterioration detection can be increased by increasing the number of strain detection means and appropriately selecting their positions (parts with different deterioration rates or parts where damage is likely). In the above, a computer is used in the actual vehicle to calculate the theoretical value of distortion at each location through memorized data map processing and arithmetic processing, and calculate the magnitude of the difference between the theoretical value of distortion and the actual measured value, as well as a predetermined value. As the number of times or time during which the exceeded difference appears is determined to be deterioration or damage, a warning or the like is issued as deterioration or damage.

FIG. 5 shows an example of the determination, and shows the case of equation (8) above, where the predetermined value
It is determined that the leaf spring 7 has deteriorated or has been damaged. This method of judgment makes it possible to take appropriate measures against suspension deterioration and damage, thereby maintaining vehicle safety. Here, the predetermined values, time, and number of times are set to the most appropriate values according to test results and the like.

As described above, the distortion of the leaf spring 7 in particular is constantly monitored, and by detecting its deterioration or damage, a warning is issued, driving and vehicle speed are regulated, and braking is performed.
Furthermore, it will be effectively used to control the vehicle's motion state and suspension, such as controlling vehicle height and attitude, controlling shock absorbers, and controlling steering.

In each of the embodiments, a cantilever type horizontal leaf spring is illustrated as the elastic member, or a two-point support type leaf spring that connects the left and right suspensions may be used.
Further, a vertical leaf spring may be used, and the suspension type is not limited to the double wishbone type of the embodiment, but may also be a strut type, etc. In short, any elastic member that constitutes a part of the suspension component may be used. [Effects of the Invention] As described above, according to the present invention, in a suspension in which a part of the suspension component is made of an elastic member,
Based on each strain of the elastic member obtained from a plurality of strain detection means, that is, comparing the theoretical value of strain at another point estimated from the measured value of strain at a certain point with the actual measured value of strain at the other point. Accordingly, deterioration or damage of the elastic member can be detected.

Therefore, it can be effectively used to control the vehicle's motion state and suspension.

In addition, by providing at least one strain detection means in a portion of the elastic member where the rate of deterioration is different from that of other strain detection means or in a portion where damage is thought to be possible, deterioration and damage can be detected effectively. You can do it.

[Brief explanation of drawings]

Figures 1 and 2 are simplified front views of each suspension structure showing application examples of the present invention, Figure 3 is a diagram showing the relationship between load and strain, and Figure 4 is a diagram showing the relationship between strain at different parts. FIG. 5 is a diagram showing the relationship between the comparison difference between the theoretical value and the measured value of time and strain representing an example of judgment of deterioration or damage. In the drawings, 1 is a wheel, 7 is an elastic member, and 9 is a strain detection means. patent

Claims (1)

[Claims] 1. A part of the suspension component is made of an elastic member, and a plurality of strain detection means are provided for detecting the strain of the elastic member, and based on the strain, it is determined whether the elastic member has deteriorated or A suspension device characterized by detecting damage. 2. The suspension according to claim 1, wherein at least one of the strain detection means is provided at a portion of the elastic member where the deterioration rate is different from that of the other strain detection means or at a portion where there is a possibility of damage. Device. 3. A theoretical value of distortion at another point estimated from the actual measurement value of the distortion at a certain point is compared with an actual measurement value of the distortion at the other point. Suspension device as described. 4. Claim 3, wherein the theoretical value of the distortion is obtained by either data map processing or arithmetic processing.
Suspension device as described.