JP2003337092A - Method for determining spring constant of dynamic torsion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a resonance frequency determined from the spring constant of static torsion after the spring constant of static torsion is determined is different from a true resonance frequency during rotation. <P>SOLUTION: A rotating shaft 4a of a dynamometer 4 is connected via a coupling 3 to a torque meter 2 fixed to a wall surface 1. The rotating shaft 4a of the dynamometer 4 is rotated to perform torsional vibration of a predetermined amplitude. Its vibration frequency is changed, and a Bode diagram is determined from the output of the torque meter 2. A resonance frequency fH is determined from the Bode diagram. The resonance frequency fH is substituted in a relational expression of the resonance frequency fH and the spring constant K to compute the spring constant K of dynamic torsion. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of determining a spring constant of dynamic torsion used for calculating a resonance frequency.

[0002]

2. Description of the Related Art FIG.
As described above, the output shaft of the engine 8 is connected to the rotary shaft 4a of the dynamometer 4 through the coupling 3 and the torque meter 2. In the engine 8, the torque changes during rotation, which induces torsional vibration of the crankshaft. When the cycle of this torsional vibration matches the engine pulsation as the resonance frequency peculiar to the crankshaft, it becomes a resonance state and vibrates violently, resulting in damage to the equipment. For this reason, it is necessary to know the resonance frequency peculiar to the shaft system and avoid operation near this frequency as much as possible. However, in a device for the purpose of testing an engine, a resonance state cannot be avoided.

Although various measures have been devised for suppressing large torsional vibrations near the resonance frequency, it is necessary to know the resonance frequency in advance, and the coupling 3
In the two-mass system in which the engine 8 is connected to one end and the dynamometer 4 is connected to the other end, it is calculated by the following formula. If the resonance frequency is f, then f = (1 / 2π) √ (K (J _E + J _D ) / J _E · J _D ) ... (1) Where K is the torsional spring constant of the coupling,
J _E is the engine inertia and J _D is the dynamometer inertia.

To obtain the resonance frequency f from the equation (1),
The torsional spring constant "K" of the coupling must first be determined. Conventionally, a device as shown in FIG. 2 is used to obtain the torsion spring constant “K”. The load W is applied to the other end of the coupling 3 whose one end is fixed to the wall surface 1 via the arm 6.
Is applied to the coupling 3 to apply a static torque T, the torsion angle θ of the coupling 3 with respect to the torque T is measured, and the torsion spring constant “K” when the coupling 3 is twisted from the relationship between T and θ Was being asked.

[0005]

However, if the spring constant "K" of the torsion is obtained by measuring the torsion angle θ by adding the static torque T, the damping effect does not appear, and the obtained spring constant of the torsion is obtained. Even if "K" is substituted into the equation (1) to obtain the resonance frequency f, it becomes different from the true resonance frequency f during rotation.

Therefore, an object of the present invention is to provide a method for determining the spring constant of dynamic torsion that solves the above problems.

[0007]

In order to achieve the above object, the method of indexing the spring constant of dynamic torsion according to claim 1 is configured so that the other end of the shaft, one end of which is connected to a fixed torque meter, is connected. Is rotated to perform torsional vibration, the vibration frequency is changed to obtain a Bode diagram from the output of the torque meter, the resonance frequency is obtained from the Bode diagram, and the relationship between the torsion spring constant and the resonance frequency is obtained. It is characterized in that the spring constant of torsion is calculated from the equation.

The resonance frequency can be obtained by substituting the spring constant obtained by the method for determining the spring constant of the dynamic torsion into the above relational expression.

In the structure of the method for determining the spring constant of the dynamic torsion according to the second aspect, the shaft is rotated to perform torsional vibration, and the vibration frequency is changed to obtain the rotation fluctuation from the output of the rotation detector. The Bode diagram is obtained from the rotation fluctuation, the resonance frequency is obtained from the Bode diagram, and the torsion spring constant is calculated from the relational expression between the torsion spring constant and the resonance frequency.

By substituting the spring constant obtained by such a method for determining the spring constant of dynamic torsion into the above relational expression, the resonance frequency can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for determining a spring constant of dynamic torsion according to the present invention will be described below.

(A) First Embodiment First, the first embodiment will be described. A rotary shaft 4a of a dynamometer 4 is connected to a torque meter 2 fixed to a wall surface 1 via a coupling (shaft) 3 as shown in FIG. The rotating shaft 4a of the dynamometer 4 is rotated to perform torsional vibration with a constant amplitude. The excitation frequency is changed, the Bode diagram is obtained from the output of the torque meter 2, and the resonance frequency f _H is obtained from the Bode diagram. On the other hand, the following relationship holds between the resonance frequency f _H and the spring constant K of the dynamic torsion.

[0013] _{f H = (1 / 2π)} √ (K / J D) ··· (2) (2) When obtaining the K from the _{equation, K = J D (2πf H} ) 2 ··· (3) becomes , The resonance frequency f _H and the dynamometer inertia J _D
By substituting and into the equation (3), the spring constant K of the dynamic torsion can be obtained.

The resonance frequency f can be obtained by substituting the spring constant K of the dynamic torsion thus obtained into the above equation (1). Since the resonance frequency f obtained here includes a dynamic element, it has a value close to the actual state.

(B) Second embodiment Next, the second embodiment will be described.

In the first embodiment, the Bode diagram is obtained by detecting the output of the torque meter, and the resonance frequency f is calculated from the Bode diagram.
_Although the spring constant K of the dynamic torsion was calculated by calculating _H and substituting the resonance frequency f _H into the equation (3), the rotation fluctuation was calculated from the rotation detector 5 of the dynamometer of FIG. 1 instead of the torque meter. It is also possible to obtain the Bode diagram from the rotation fluctuation and obtain the spring constant K of the dynamic torsion from the Bode diagram in the same manner as in the first embodiment.

[0017]

As is apparent from the above description, according to the method for determining the spring constant of dynamic torsion according to claims 1 and 2, not the spring constant of static torsion but the spring constant of dynamic torsion is obtained. As a result, a more accurate resonance frequency can be obtained close to the operating state. Therefore, it is possible to prevent the occurrence of breakage of the device due to the vibration due to the resonance.

[Brief description of drawings]

FIG. 1 is a configuration diagram for carrying out Embodiments 1 and 2 of a method for determining a spring constant of dynamic torsion according to the present invention.

FIG. 2 is a configuration diagram for carrying out a conventional method of indexing a spring constant of static torsion.

FIG. 3 is a configuration diagram of a device for performing an engine test.

[Explanation of symbols]

2 ... Torque meter 3 ... Coupling 4 ... Dynamometer 4a ... rotary shaft 5 ... Rotation detector

Claims (2)

[Claims] 1. A Bode diagram is obtained from the output of the torque meter by rotating the other end of a shaft, one end of which is connected to a fixed torque meter, to perform torsional vibration, changing the vibration frequency, A method for determining a spring constant of dynamic torsion, characterized in that the resonance frequency is obtained from the Bode diagram and the spring constant of torsion is calculated from a relational expression between the spring constant of torsion and the resonance frequency. 2. The shaft is rotated to perform torsional vibration, the vibration frequency is changed to obtain the rotation fluctuation from the output of the rotation detector, the Bode diagram is obtained from the rotation fluctuation, and the Bode diagram is calculated from the Bode diagram. A method for determining a spring constant of a dynamic torsion, which comprises obtaining a resonance frequency and calculating a spring constant of the torsion from a relational expression between the spring constant of the torsion and the resonance frequency.