JPH0247306Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a torsional damper used primarily for damping torsional vibration of a rotating shaft such as a crankshaft of an engine.

[Conventional technology]

Traditionally, it has been used as a torsional damper installed on the crankshaft of automobile engines.
As shown schematically in FIG. 5, an annular hub a is pivotally attached to the tip of the crankshaft, and a vibration ring c is coaxially disposed outside the hub a. A device that is connected via a ring b is widely known.

[Problem that the invention attempts to solve]

By the way, the natural frequency f of the above-mentioned torsional damper is as follows, where k is the spring constant of elastic ring b, and m is the inertial mass of vibration ring c. However, the elasticity of the rubber that is the material of the elastic ring b changes depending on the temperature; in other words, at low temperatures it becomes harder and the spring constant k increases, so the natural frequency f of the torsional damper increases, and at high temperatures Sometimes, on the contrary, it becomes soft and the spring constant k becomes small, so that the natural frequency f decreases. Therefore, a torsional damper that has been set with an appropriate natural frequency at room temperature will have a higher natural frequency than the appropriate value when it is cold, so the crankshaft will not be able to operate at low speeds such as when starting an engine. Since the vibrations are not sufficiently damped and the natural frequency becomes lower than the appropriate value at high temperatures, the crankshaft vibrations at high speeds are not sufficiently damped and noise generation becomes a problem. It was becoming.

In view of these problems, the present invention aims to provide a structure that can exhibit a good vibration damping function regardless of changes in temperature conditions.

[Means for solving problems]

In order to solve the above problem, the torsional damper of the present invention has a vibration ring which is a mass body, a main vibration ring connected to a hub via an elastic ring, and a main vibration ring located on the outer peripheral side of the main vibration ring. and at least one auxiliary vibrating ring which is made of a material having a larger thermal expansion coefficient than the main vibrating ring and whose interference with respect to the main vibrating ring is zero at a predetermined temperature.

[Effect]

That is, according to the present invention, when the temperature falls below the predetermined temperature, the outer peripheral side sub-vibration ring having a large coefficient of thermal expansion shrinks more than the inner peripheral side main vibration ring. These main
The auxiliary vibration rings are pressed against each other on their opposing circumferential surfaces and become integral, increasing the inertial mass and working to lower the natural frequency. Furthermore, when the temperature rises above the predetermined temperature, the outer auxiliary vibration ring, which has a larger coefficient of thermal expansion, expands more than the inner main oscillation ring and separates from the main oscillation ring. Only the main vibration ring connected to the hub via the ring becomes a de facto vibration ring, and the inertial mass becomes small, working to increase the natural frequency.

〔Example〕

Embodiments of the torsional damper of the present invention will be described below with reference to the drawings.

First, FIGS. 1 and 2 show a first embodiment, in which reference numeral 1 is a hub that is pivotally attached to the tip of the crankshaft of the engine, and 3 is a vibration ring that is coaxially arranged on the outside of the hub 1. be. The vibration ring 3
is the inner main vibration ring 3 made of cast iron.
a, and a sub-vibration ring 3b which is located on the outer circumferential side of the main vibrating ring 3a and is made of a material such as brass or aluminum having a larger coefficient of thermal expansion than the cast iron material, and the inner circumferential surface of the main vibrating ring 3a. An elastic ring 2 made of a rubber material is vulcanized and bonded between the outer peripheral surface of the hub 1 and the outer peripheral surface of the hub 1. Both main and sub vibration rings 3a, 3b
The diameter dimensions of the opposing circumferential surfaces 3a' and 3b' are the same when the temperature is 20°C (the interference between both 3a and 3b is zero), and when the temperature is lower than 20°C, the thermal expansion Because the auxiliary vibration ring 3b tends to contract more than the main vibration ring 3a due to the difference in coefficients, as shown in FIG.
a' and 3b' are tightly crimped, and when the temperature rises above 20°C, the sub-vibrating ring 3b expands more than the main vibrating ring 3a. 3a and 3b are separated from each other. Parts of the opposing circumferential surfaces 3a', 3b' are formed in a stepped shape to prevent the sub-vibrating ring 3b from falling off to the right in the figure when both the main and sub-vibrating rings 3a, 3b are separated from each other. In addition, a pulley member 4, which is fixed to the hub 1 with bolts 5 and extends toward the outer circumferential side of the vibration ring 3, is responsible for preventing the sub-vibration ring 3b from falling off in the left direction in the drawing. Reference numeral 6 denotes a sliding bearing attached to a part of the inner surface of the pulley member 4 and in contact with the auxiliary vibration ring 3b.

According to the above configuration, under a temperature condition of 20°C or less, both the main and sub vibration rings 3a and 3b are integrated and the inertial mass becomes large, so the spring constant is reduced by hardening of the elastic ring 2 in cold weather etc. It is possible to prevent the natural frequency from increasing due to increasing
On the other hand, when the temperature is higher than 20°C, both the main and sub vibration rings 3a and 3b separate from each other, and only the main vibration ring 3a performs its original function as a vibration ring, and its inertial mass becomes smaller. It is possible to prevent the natural frequency from decreasing due to a decrease in the spring constant due to the softening of the elastic ring 2 at high temperatures.

Next, in the second embodiment shown in FIG. 3, a sleeve 7 is interposed between the main vibration ring 3a and the elastic ring 2, and the movement of the sub vibration ring 3b existing on the outer periphery of the main vibration ring 3a in the thrust direction is prevented. In the third embodiment shown in FIG. 4, the elastic ring 2 is restricted by a cross-sectional annular holding portion 8 provided on the pulley member 4, and the elastic ring 2 is connected to the hub 1 by a pulley groove 4' on the outer peripheral surface. The auxiliary vibration ring 3b, which is press-fitted between the opposing peripheral surfaces of the main vibration ring 3a having In each example, as in the first embodiment, the main vibration ring 3
A and a sub-vibration ring 3b having a larger coefficient of thermal expansion than the main vibrating ring 3a move toward and away from each other at their opposing circumferential surfaces 3a' and 3b' in response to temperature changes.

In each of the above embodiments, only one auxiliary vibration ring 3b is used, but by providing a plurality of main vibration rings with mutually different coefficients of thermal expansion, it is possible to more finely adjust the natural frequency in response to temperature changes. Become.

[Effect of idea]

As explained above, the torsional damper according to the present invention includes a main vibration ring connected to a hub via an elastic ring, and a part on the outer circumferential side of the main vibration ring that expands thermally more than the main vibration ring. It is composed of sub-oscillation rings with large coefficients, and when the temperature drops below a certain level, these main and sub-oscillation rings become integrated due to the difference in contraction, acting to lower the natural frequency, and conversely, In some cases, the main and sub vibration rings separate due to the expansion difference and act to increase the natural frequency.
The hardening of the elastic ring increases the natural frequency, which prevents damage to the damping function when starting the engine (at low speeds), and the softening of the elastic ring at high temperatures reduces the natural frequency. This has an extremely excellent effect in that it can prevent the damping function from being impaired at high rotation speeds.

[Brief explanation of the drawing]

Fig. 1 is a half-cut sectional view showing an embodiment of the present invention in a state at low temperature, Fig. 2 is a half-cut sectional view showing the state at high temperature, and Fig. 3 is a half-cut sectional view showing the second embodiment. , FIG. 4 is a half-cut sectional view showing the third embodiment, and FIG. 5 is a schematic half-cut sectional view showing the conventional structure. DESCRIPTION OF SYMBOLS 1...Hub, 2...Elastic ring, 3...Vibration ring, 3a...Main vibration ring, 3b...Sub-vibration ring, 3a', 3b'...Opposing peripheral surface, 4...Pulley member, 4' ... Pulley groove, 5 ... Bolt, 6 ... Sliding bearing, 7 ... Sleeve, 8 ... Annular holding part, 9
... Concave stepped portion, 10 ... Flange-like member.

Claims (1)

[Scope of utility model registration request] The vibration ring 3 is connected to the hub 1 via the elastic ring 2.
A main vibration ring 3a connected to the main vibration ring 3a, and a material on the outer circumferential side of the main vibration ring 3a that is made of a material having a larger coefficient of thermal expansion than the main vibration ring 3a and has an interference with respect to the main vibration ring 3a at a predetermined temperature. A torsional damper comprising at least one sub-vibration ring 3b having a zero vibration.