JPH11278033A - Tuning device for suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To tune a spring constant of a spring and damping force based on requirement from a user, by inputting a desired spring constant on the front or rear wheel side into a computing unit. SOLUTION: A computing unit first calculates a current vehicle spring constant K (Kf: front wheel side spring constant, Kr: rear wheel side spring constant), damping force C of a shock absorber (Cf: front wheel side damping force, Cr: rear wheel side damping force), wheel load W (Wf: front wheel side load, Wr: rear wheel side load), under the condition of detecting signal input from a wire type displacement sensor and a ground load measuring device, and based on prerecorded information. Then, the computing unit calculates a desired vehicle spring constant K" (K"f: front wheel side spring constant, K"r: rear wheel side spring constant) and damping force C" of a shock absorber (C"f: front wheel side damping force, C"r: rear wheel side damping force) after hard suspension tuning, and lightening of a load wheel adequate to the hard suspension tuning and indicates it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can set the spring constant of a spring and the damping force of a shock absorber rationally and appropriately on the basis of a user's request, can perform the rational tuning thereof, and improve the riding comfort. A suspension tuning device that obtains a change ratio of tire flatness suitable for hard suspension tuning, enables selection of a corresponding road wheel and tire, and promotes weight reduction.

[0002]

2. Description of the Related Art Conventionally, automobile enthusiasts exchange suspensions, shock absorbers, springs, link bushes, etc., road wheels, tires, etc.
The so-called hard suspension tuning for improving the damping force and the spring constant was performed to obtain a desired riding comfort. At that time, the selection and tuning of replacement parts was performed by trial and error, relying on experience and intuition, and thus lacked rationality and reproducibility, and a satisfactory ride quality could not be obtained.

The applicant has developed a shock absorber damping force measuring device capable of measuring the damping force and spring constant of a shock absorber, and has disclosed this in Japanese Patent Application Laid-Open No. 9-15238.
No. 9 proposes this.

That is, this conventional apparatus includes a vehicle body displacement detecting means, a wheel ground contact load detecting means, a damping force calculating means, and a speed calculating means for calculating a piston speed of a shock absorber. The quality of the damping force of the absorber and the degree of deterioration can be accurately grasped.

[0005] However, the above-mentioned apparatus is limited to the quantitative measurement of the shock absorber, and the selection and tuning of the replacement part still rely on experience and intuition, so that the rationalization and reproducibility thereof cannot be realized. Was.

[0006]

SUMMARY OF THE INVENTION The present invention solves such a problem and can set the spring constant and damping force of the spring of the shock absorber rationally and appropriately on the basis of the user's request. In addition to giving a good ride quality, it also indicates the change rate of tire flatness suitable for hard suspension tuning, enables selection of corresponding road wheels and tires, and promotes weight reduction. An object of the present invention is to provide a suspension tuning device.

[0007]

According to a first aspect of the present invention, there is provided a tuning system for a suspension including a computing unit, wherein information on a spring constant of a spring before tuning, a damping force of a shock absorber, and a wheel load is provided. And a desired spring constant for the front wheel or the rear wheel can be input to the calculator, and the spring constant of each wheel and the damping force of the shock absorber can be calculated based on the input information. The spring constant of the spring and the damping force of the shock absorber can be set rationally and appropriately based on the user's request, so that the tuning can be performed rationally and a good ride quality can be obtained.

According to a second aspect of the present invention, the spring constant is calculated based on the natural frequency of the spring to prevent an error in the spring constant due to the magnitude of the vehicle weight and to obtain a stable and accurate spring constant. . According to a third aspect of the present invention, there is provided a suspension tuning apparatus provided with an arithmetic unit, wherein an arithmetic unit capable of inputting information on a spring constant of a spring before the tuning, a damping force of a shock absorber, and wheel load is provided. A desired spring constant of the front wheel or the rear wheel can be input to the shock absorber based on the input information, and a relational expression between a damping force of the shock absorber and a spring constant of the spring, a damping coefficient ratio and a proper range thereof. Can be calculated, and a damping force suitable for the spring can be selected based on the damping coefficient ratio.

According to a fourth aspect of the present invention, the unsprung resonance frequency is set higher than that before tuning, the flatness of the tire and the change ratio thereof can be calculated based on the frequency, and the interval between the sprung and unsprung resonance frequencies is calculated. They are separated to prevent adverse effects due to their approach, and to maintain the tire's contact property. According to the fifth aspect of the present invention, instead of setting the unsprung resonance frequency to be high, the weight of the road wheel is reduced by approximately the same ratio, the weight of the road wheel is reduced, and the flatness of the tire is changed to change the unsprung resonance. This is suitable when the frequency cannot be set high.

According to a sixth aspect of the present invention, a spring constant, a damping force, and a wheel load of a spring before tuning are measured and calculated through a damping force measuring device of a shock absorber, and the information can be input to the calculator. , So that this kind of tuning work can be performed accurately and easily.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 to 6, reference numeral 1 denotes a vehicle to be subjected to so-called hard suspension tuning, and a suspension is provided facing its front and rear axles (not shown). The upper end of the shock absorber 2 is connected to the vehicle body 3 and the lower end of the shock absorber 2 is connected to each axle (not shown). A damping force measuring device 4 is provided.

The damping force measuring device 4 includes a wire type displacement sensor 6 for detecting a relative displacement between the wheel 5 and the vehicle body 3 linked to the shock absorber 2 and a load cell for detecting the load on each wheel 5. A measuring unit 7; an arithmetic unit 8 such as a personal computer for arithmetically processing detection signals from the wire displacement sensor 6 and the ground load measuring unit 7; an output device 9 such as a printer;
And

The wire type displacement sensor 6 is detachably attached to an axle or a wheel through a fixing jig 11, and is connected to a vehicle body via a bracket 13 by connecting a tip end of a wire 12 projecting outward. 3, and can output a signal corresponding to the relative displacement between the vehicle body 3 and the wheel 6 to the arithmetic unit 8.

The ground contact load measuring means 7 is disposed between the wheel 5 and the floor surface 14. In other words, the wheel 5 is placed on the measuring means 7, and the wheel load W acting on the wheel 5 is adjusted. (W
f: front wheel load, Wr: rear wheel load), and the signal can be output to the arithmetic unit 8.

The arithmetic unit 8 is operated under the condition that detection signals are input to the wire type displacement sensor 6 and the ground contact load measuring means 7.
Based on the information stored in advance, first, the spring constant K (K) of the current vehicle 1, that is, the vehicle 1 before hard suspension tuning is performed.
f: front wheel side spring constant, Kr: rear wheel side spring constant) and the damping force C of the shock absorber (Cf: front wheel side damping force, C
r: rear wheel side damping force) and wheel load W (Wf: front wheel side load,
Wr: rear wheel side load) is calculated.

In this case, the spring constant K is statically determined by the displacement Xo.
From the wheel load variation △ W when adding, K = △ W / Xo
(Kg / mm).

The damping force C of the shock absorber is:
The relative displacement between the vehicle body 3 and the wheels 5 is detected by the wire type displacement sensor 6, and the wheel load W when the relative displacement is zero is measured as the damping force. Wheel load W
Is obtained from the measured value of the grounding load measuring means 7. The above-mentioned damping force is individually obtained as the extension-side damping force when elongating, and as the contraction-side damping force when contracting. The representative value at a piston speed of 0.3 m / s is obtained by linear approximation.

Next, the calculator 8 calculates the current calculated spring constant K of the vehicle 1, the damping force C of the shock absorber,
Based on the information stored in advance under the condition of input of the wheel load W, as shown in FIG. 2, a desirable spring constant K "(K"f; front-wheel-side spring constant, K "r; rear-wheel-side of the vehicle 1 after hard suspension tuning. Spring constant), a desirable shock absorber damping force C "(C"f; front wheel side damping force, C "r; rear wheel side damping force), a change ratio A of tire flatness suitable for hard suspension tuning, and a hard suspension. It calculates and gives instructions on how to reduce the weight of the road wheel suitable for tuning.

Among them, a desirable spring constant K "(K"
When calculating f: front-wheel-side spring constant and K “r: rear-wheel-side spring constant), the sense of the hardness of the spring varies depending on the weight of the vehicle 1. The spring spring constant of the hard suspension is determined.

The above determination flow is as shown in FIG. 3, and the calculated current spring constant K, shock absorber damping force C,
The current natural frequency F is calculated based on the wheel load W. The general formula of the frequency is F = (1 / 2π) × “(9.8 K /
W) (in the present specification, “symbols are used instead of radicals. The same applies to the following description). Among them, the natural frequency of the front wheel is Ff = (１ ／ π) ד ( 9.8Kf / W
f), and the natural frequency of the rear wheel is Fr = (1
/2π)ד(9.8 Kr / Wr).

Next, a user who is the user of the vehicle 1 selects a desired spring constant K "f,
To enter. In this case, m may be designated when the desired spring constant K "f is set to be m times (m> 0) the current spring constant Kf.

Then, the natural frequencies F "f, F" r of the front and rear wheels are calculated based on the spring constant K "f. That is, the new natural frequency of the front wheels is F" f = (1 / 2π) × “(9.
In calculating the natural frequency of the rear wheel, first, a hard suspension spring constant K "r of the rear wheel is calculated based on the balance between the front and rear wheels.

Then, K "r = K" f * (Kr / Kf)
Thus, F ″ r = (ππ) × “(9.8K“ r / W
r). In this case, if the value of Kr / Kf is limited to an actually measured value, there is a possibility that accuracy may be lost due to settling or the like. Therefore, it is also possible to use a ratio of reference data.

Next, the desired damping force C * of the shock absorber (C * f: front wheel side damping force, C * r: rear wheel side damping force)
Is determined as shown in FIG. 4. The damping force C * of the shock absorber suitable for the spring constants K "r, K" f is selected based on the damping coefficient ratio C / Cc.

The above-mentioned damping coefficient ratio is C / Cc = C / 2.
“(WK / 9.8) × 100%. Here, the damping coefficient is C = damping force C * of the shock absorber / piston speed, that is, C = (C / Cc) × ｛2” (WK /
9.8) $ / 100%. Therefore, from the above equation, C * =
(C / Cc) × [{2 “(WK / 9.8)} / 100
%] × piston speed, and appropriate zone value of C / Cc 3
Substituting 0-50% and piston speed 0.3m / s,
Shock absorber damping force C * = (30-50) x
0.006 × “(WK / 9.8).

Therefore, the damping force C * f of the shock absorber for the front wheels = (30 to 50) × 0.006 × “(W
K "f / 9.8), and the damping force C * r of the rear wheel shock absorber = (30-50) x 0.006 x" (W
K "r / 9.8).

In this case, since C * f and C * r are average values of expansion and contraction, they are separated into expansion and contraction ratios. That is, it is expressed by extension side damping force = 2 × C * f × (current extension side damping force / current extension / contraction total damping force), and compression side damping force = 2 × C * fx × (current contraction side damping force / current extension / contraction) (Total damping force).
Therefore, if the C * f and C * r are substituted into the above equation, it can be seen that the expansion / contraction-side damping force has a certain range.

Further, in determining a tire specification suitable for a desired hard suspension, since the sprung resonance frequency increases due to the hard suspension, consideration should be given to raising the unsprung resonance frequency so as not to approach the resonance point, and maintaining the grounding property. Is valid.

The above determination flow is as shown in FIG. 5. The unsprung natural frequency due to the hard suspension is F "u = Fu (current unsprung natural frequency) + (F" -F) (sprung natural frequency. Change).

Here, the current unsprung natural frequency is Fu
= (1 / 2π) × “(9.8 Ku / Wu).
Where Ku: tire longitudinal spring constant, Wu: unsprung weight
These are representative values (Ku = 20,000 kg / m, Wu = 2
0 kg) to obtain an approximate solution of Fu = 15.8 Hz. Therefore, F "u = 15.8 + (F" -F) (change in sprung natural frequency).

Therefore, when a desirable tire longitudinal spring constant is obtained, K “u = (F” u × 2π) 2 × (Wu / 9.8)
Is represented by The tire flatness ratio, that is, the change ratio of the tire height / tire width A = α (K “u−Ku), where the coefficient α is the relationship between the tire flatness ratio and the tire longitudinal spring constant. It corresponds to the slope of the straight line shown.

On the other hand, when the unsprung natural frequency Fu cannot be increased by changing the tire flatness as described above, it is effective to reduce the weight of the road wheel at the same ratio. That is, Fu = (1 / 2π) × “(9.8 Ku /
From Wu), an increase in the tire longitudinal spring constant of Ku → K “u is equivalent to a decrease in unsprung weight (road wheel + tire, etc.) of Wu → W“ u.

Therefore, instead of changing the tire flatness, an equivalent effect can be obtained by reducing the weight of the road wheel. Therefore, W "u / Wu = Ku / K" u, W "u
= Wu × Ku / K “u, that is, W“ u−Wu = weight reduction required for the road wheel.

The suspension tuning apparatus configured as described above has a desirable spring constant K "(K"f; front-wheel-side spring constant, K "r; rear-wheel-side of the vehicle 1 after hard suspension tuning as shown in FIGS. Spring constant), a desirable shock absorber damping force C * (C * f; front wheel side damping force, C * r; rear wheel side damping force), a change ratio A of the tire flatness suitable for hard suspension tuning, and a hard suspension. An arithmetic unit 8 storing information for calculating the weight reduction of a road wheel suitable for tuning is provided.

When performing hard suspension tuning using the above tuning device, the damping force measuring device 4 of the shock absorber 2 is used, and the spring constant K of the current vehicle 1 is used.
Then, the damping force C of the shock absorber and the wheel load W are measured.

At the time of the measurement, each of the contact load measuring means 7 is arranged on the floor surface 14 corresponding to the position of the front and rear wheels of the vehicle 1, and the front and rear wheels 5 ride on the measuring means 7 and stand still. Then, the vehicle body 3 is pushed up and down several times through a bumper or the like to move the vehicle body 3 up and down substantially periodically.

In this way, the vehicle body 3 is displaced with respect to the wheels 5, and the load changes according to the vertical movement of the ground contact load measuring means 7 are generated. Is input to the calculator 8 from the contact load measuring means 7. The computing unit 8 reads the detection signal, and calculates the contact load W
And the displacement X of the vehicle body 3 while continuously measuring the displacement X
The piston speed V of the shock absorber 2 is calculated from the differential value of.

In this case, the spring constant K is statically determined by the displacement Xo.
K = ΔW / Xo from the wheel load variation ΔW when adding
(Kg / mm).

The damping force C of the shock absorber is
The relative displacement between the vehicle body 3 and the wheels 5 is detected by the wire displacement sensor 6, and the wheel load W when the relative displacement is zero is measured as the damping force.

The wheel load W is obtained from the measured value of the contact load measuring means 7. In this case, these numerical values may be individually measured and calculated by appropriate means instead of being obtained by the damping force measuring device 4, and may be obtained.

Thus, the current spring constant K of the vehicle 1 and
After measuring the damping force C of the shock absorber and the wheel load W,
The arithmetic unit 8 performs the hard suspension tuning of the present invention.

That is, the arithmetic unit 8 performs hard suspension as shown in FIG. 2 on the basis of information stored in advance under the conditions of the current spring constant K of the vehicle 1, the damping force C of the shock absorber, and the input of the wheel load W. Desired spring constant K "(K"f; front-wheel-side spring constant, K "r; rear-wheel-side spring constant) of the tuned vehicle 1 and desired damping force C * of the shock absorber
(C * f: front wheel side damping force, C * r: rear wheel side damping force),
The change ratio A of the tire flatness suitable for the hard suspension tuning and the weight reduction of the road wheel suitable for the hard suspension tuning are calculated and instructed.

Among them, a desirable spring constant K “(K”
f: front-wheel-side spring constant, K “r: rear-wheel-side spring constant) determines the spring suspension constant of the hard suspension based on the natural frequency F because the sense of the hardness of the spring varies depending on the weight of the vehicle 1. I do.

The above determination flow is as shown in FIG. 3, and the calculated current spring constant K, shock absorber damping force C,
The current natural frequency F is calculated based on the wheel load W. The general formula of the frequency is F = (1 / 2π) × “(9.8 K /
W), the natural frequency of the front wheel is Ff = (１ ／)
π) × “(9.8 Kf / Wf), and the natural frequency of the rear wheel is Fr = (１ ／ π) ד (9.8 Kr / W
r)

Next, a user who is the user of the vehicle 1 selects a desired spring constant K "f,
To enter. In this case, it is also possible to specify m to make the desired spring constant K "f m times (m> 0) the current spring constant Kf.

Then, the natural frequencies F "f, F" r of the front and rear wheels are calculated based on the spring constant K "f. That is, the new natural frequency of the front wheels is F" f = (1 / 2π) × “(9.
When calculating the natural frequency of the rear wheel, a hard suspension spring constant K "r of the rear wheel is first calculated based on the balance between the front and rear wheels.

The rear suspension hard suspension spring constant K “r is K
From "r = K" f * (Kr / Kf), F "r = (1/2
π) × “(9.8K“ r / Wr). in this case,
If Kr / Kf is limited to an actually measured value, there is a possibility that accuracy may be lost due to settling or the like, so that a ratio of reference data can be used.

Next, the desired damping force C * of the shock absorber (C * f: front wheel side damping force, C * r: rear wheel side damping force)
Selects the damping force C * of the shock absorber suitable for the spring constants K "r, K" f based on the damping coefficient ratio C / Cc in the determination flow as shown in FIG.

The damping coefficient ratio is given by C / Cc = ｛C / 2
“(WK / 9.8)｝ × 100%, where
The damping coefficient is C = damping force C * of the shock absorber / piston speed, that is, C = (C / Cc) × ｛2 “(WK
/9.8)｝/100%. Therefore, from the above equation, C * =
(C / Cc) × [{2 “(WK / 9.8)} / 100
%] × piston speed, and appropriate zone value of C / Cc 3
Substituting 0-50% and piston speed 0.3m / s,
Shock absorber damping force C * = (30-50) x
0.006 × “(WK / 9.8).

Therefore, the damping force C * f of the shock absorber for the front wheels = (30 to 50) × 0.006 × “(W
K "f / 9.8), and the damping force C * r of the rear wheel shock absorber = (30-50) x 0.006 x" (W
K "r / 9.8).

In this case, since C * f and C * r are average values of expansion and contraction, they are separated into expansion and contraction ratios. That is, it is expressed by extension side damping force = 2 × C * f × (current extension side damping force / current extension / contraction total damping force), and compression side damping force = 2 × C * fx × (current contraction side damping force / current extension / contraction) (Total damping force).
Therefore, if the C * f and C * r are substituted into the above equation, it can be seen that the expansion / contraction-side damping force has a certain range.

Further, when determining tire specifications suitable for a desired hard suspension, since the sprung resonance frequency increases due to the hard suspension, consideration should be given to raising the unsprung resonance frequency so as not to approach the resonance point, and the grounding property should be maintained. Is valid. The damping coefficient ratio is C / Cc = ｛C / 2
“(WK / 9.8)｝ × 100%, where
Since the damping coefficient is C = damping force C / piston speed of the shock absorber, the appropriate zone of C / Cc is 30 to 50%, and the piston speed is 0.3 m / s, the damping force of the shock absorber C = (30 to 50) × 0.006 × “(WK
/9.8).

The above determination flow is as shown in FIG. 5, and the unsprung natural frequency due to hard suspension is F "u = Fu (current unsprung natural frequency) + (F" -F) (sprung natural frequency) Change).

Here, the current unsprung natural frequency is Fu
= (1 / 2π) × (“Represented by (9.8 Ku / Wu). Ku; tire longitudinal spring constant, Wu; unsprung weight, these are representative values (Ku = 20,000 kg / m, Wu = 20)
kg) to obtain an approximate solution of Fu = 15.8 Hz.
Therefore, F "u = 15.8 + (F" -F) (change in sprung natural frequency).

Then, when a desirable tire longitudinal spring constant is obtained, K “u = (F” u × 2π) 2 × (Wu / 9.8)
Is represented by The tire flatness ratio, that is, the change ratio of the tire height / tire width A = α (K “u−Ku), where the coefficient α is the relationship between the tire flatness ratio and the tire longitudinal spring constant. It corresponds to the slope of the straight line shown.

On the other hand, when the unsprung natural frequency Fu cannot be increased by changing the tire flatness as described above, it is effective to reduce the weight of the road wheel at the same ratio. That is, Fu = (1 / 2π) × “(9.8 Ku /
From Wu), an increase in the tire longitudinal spring constant of Ku → K “u is equivalent to a decrease in unsprung weight (road wheel + tire) of Wu → W“ u.

Therefore, instead of changing the tire flatness, an equivalent effect can be obtained by reducing the weight of the road wheel. Therefore, W "u / Wu = Ku / K" u, W "u
= Wu × Ku / K “u, that is, W“ u−Wu = weight reduction required for the road wheel.

As described above, according to the present invention, the desired spring constant K "(K"
f: front-wheel-side spring constant, K “r: rear-wheel-side spring constant) and desirable damping force C * of the shock absorber (C * f: front-wheel-side damping force, C * r: rear-wheel-side damping force) Therefore, as compared with a conventional trial-and-error tuning method, tuning can be rationally performed based on the calculated value, and a desired ride quality can be obtained.

Further, since the change rate A of the tire flatness ratio suitable for the hard suspension tuning is instructed according to the above calculated value, it is possible to select a road wheel and a tire suitable for the hard suspension tuning desired by the user, and to reduce the weight. Can be promoted.

In the above-described embodiment, the damping force of the shock absorber of the desired hard suspension is determined after the spring constant of the desired hard suspension spring is determined. However, the order may be reversed. The operation can be diversified.

[0061]

According to the first aspect of the present invention, the spring constant of the spring before tuning, the damping force of the shock absorber,
And an arithmetic unit capable of inputting information on wheel loads. A desired spring constant of a front wheel or a rear wheel can be input into the arithmetic unit. Based on the input information, a spring constant of each wheel and a damping of a shock absorber are provided. Since the force can be calculated, the spring constant of the spring and the damping force of the shock absorber can be set rationally and appropriately based on the user's request, and the rational tuning can be performed and a good ride quality can be obtained. effective.

According to the second aspect of the present invention, since the spring constant is calculated based on the natural frequency of the spring, errors in the spring constant due to the magnitude of the vehicle weight can be prevented, and a stable and accurate spring constant can be obtained. . According to a third aspect of the present invention, an arithmetic unit capable of inputting information on a spring constant of a spring before tuning, a damping force of a shock absorber, and wheel load is provided, and a desired spring constant of a front wheel or a rear wheel is provided in the arithmetic unit. It is possible to calculate the damping force of the shock absorber based on the relational expression between the damping force of the shock absorber and the spring constant of the spring based on the input information, the damping coefficient ratio and its proper range. There is an effect that a damping force suitable for the spring can be selected according to the damping coefficient ratio.

According to the fourth aspect of the present invention, the unsprung resonance frequency is set higher than before tuning, and the flatness of the tire and the change ratio thereof can be calculated based on the frequency. By increasing the distance, adverse effects due to the approach can be prevented, and the tire's contact property can be maintained. The invention of claim 5 reduces the weight of the road wheel by approximately the same ratio instead of setting the unsprung resonance frequency to a high value. This has a suitable effect when the resonance frequency cannot be set high.

According to a sixth aspect of the present invention, a spring constant, a damping force, and a wheel load of a spring before tuning are measured and calculated through a damping force measuring device of a shock absorber, and the information can be input to the calculator. Therefore, this kind of tuning operation can be performed accurately and easily.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing the entire tuning according to the present invention.

FIG. 3 is a flowchart showing an operation state according to the present invention, showing a flow of determining a spring constant of a spring.

FIG. 4 is a flowchart showing an operation state according to the present invention, showing a flow of determining a damping force of a shock absorber.

FIG. 5 is a flowchart showing an operation state according to the present invention, showing a flow of changing a tire flatness factor.

FIG. 6 is a flowchart showing an operation state according to the present invention, which shows a reduction in the weight of a road wheel.

[Explanation of symbols]

2 Shock absorber 4 Shock absorber damping force measuring device 5 Wheel 8 Computing unit

Claims (6)

[Claims] In a suspension tuning apparatus provided with an arithmetic unit, an arithmetic unit capable of inputting information on a spring constant of a spring before tuning, a damping force of a shock absorber, and a wheel load is provided. Allows input of the desired spring constant for the front or rear wheels,
A suspension tuning apparatus characterized in that a spring constant of each wheel can be calculated based on the input information. 2. The suspension tuning apparatus according to claim 1, wherein the spring constant is calculated based on a natural frequency of the spring. 3. A suspension tuning device provided with an arithmetic unit, wherein an arithmetic unit capable of inputting information on a spring constant of a spring before tuning, a damping force of a shock absorber, and a wheel load is provided. Alternatively, it is possible to input a desired spring constant on the rear wheel side, and based on the input information, the relational expression between the damping force of the shock absorber and the spring constant of the spring, the damping coefficient ratio and the damping of the shock absorber based on the appropriate range thereof. A suspension tuning device characterized in that the force can be calculated. 4. The suspension tuning device according to claim 1, wherein the unsprung resonance frequency is set higher than before tuning, and the tire flatness ratio and its change ratio can be calculated based on the unsprung resonance frequency. 5. The suspension tuning apparatus according to claim 1, wherein the weight of the road wheel is reduced by substantially the same ratio instead of setting the unsprung resonance frequency to be high. 6. The apparatus according to claim 1, wherein a spring constant, a damping force, and a wheel load of the spring before tuning are measured and calculated through a damping force measuring device of a shock absorber, and the information can be input to the calculator. A suspension tuning apparatus according to claim 3.