JPH07310784A - Minimizing device for dynamic spring rigidity of elastomer mount in frequency selective manner - Google Patents

Abstract

PURPOSE: To improve a vibration isolating property at idling speed of an internal combustion engine by frequency-selectively minimizing dynamic spring rigidity of an elastomer mount. CONSTITUTION: Damping body mass 2 is connected in parallel to a main spring 4 supporting main mass 1, this damping body mass 2 is connected to the main mass 1 through a first damping body spring 6, and it is connected to and supported on a foundation 5 through a second damping body spring 7. Additionally a rubber body at an at least 8 deg. phase angle of which strongly damps is used as the main spring 4, and a rubber body the phase angle of 4 deg. to 6 deg. of which weakly damps is used as the damping body springs 6, 7. Additionally, the second damping body spring 7 has higher rigidity than that of the first damping body spring 6, and a ratio of rigidity is made 2:1. Thereafter, the total of rigidity of the both damping body springs 6, 7 is made in a range of 25-75 N/mm. That is, as a phase between main mass vibration and damping body vibration is inverted, resultant force is reduced in accordance with excessive increase of the resultant force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to an elastomer mount, such as having a sedative for a given frequency range,
In particular, it relates to a device for frequency-selectively minimizing the dynamic spring stiffness of an automobile engine mount.

[0002]

2. Description of the Prior Art In the case of the known sedative device shown in FIG. 1 as prior art, a sedative mass 2 is generally supported by a spring 3 on a main mass 1 of the oscillating system in a free-vibrating manner. According to such an arrangement structure, the forced vibration of the main mass 1 caused by the generation of the road surface reaction force, the generation of the spring force or the generation of the imbalance is determined by the sedative body mass 2 and the sedative body spring 3. When the resonance occurs, it is calmed down. This soothing of the main mass in the form of a reduction of the oscillating stroke reduces the forces introduced from the main spring 4 supporting the main mass 1 to the foundation 5, ie to the insulating side of the vibration system.

However, in the case of such a system, the following problems occur. The mass, which is supported only by the spring 4, produces an over-increased resonance at certain frequency conditions. Now, when the vibration of the main mass 1 is to be damped by the sedative body 2 at a predetermined resonance frequency, two natural vibrations occur in the entire system, and the first natural vibration is the first natural vibration at a relatively low frequency. The second natural vibration exists as a natural natural vibration without a sedative body at a relatively high frequency. This gives rise to two resonant frequencies, which also lead to increased forces on the foundation.

When such a sedative body is employed for acoustic damping at no load rpm in the case of an automobile engine mount, for example, the second resonance is always obtained when the no load rpm is high. Passing points, which can lead to considerably increased internal noise when starting the vehicle.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the vibration isolation of an internal combustion engine at no load rpm by minimizing the dynamic spring stiffness of such elastomer mounts in a frequency selective manner. is there.

[0006]

According to the invention, this task is based on the fact that a sedative mass is connected in parallel to a main spring supporting the main mass, the sedative mass being connected via the first sedative spring to the main mass. And is connected to and supported by the foundation via a second sedative spring.

[0007]

The sedative body is therefore excited by the movement of the main mass via the first sedative body spring, and then via the second sedative body spring, directs a force to the foundation. This exerts on the foundation the sum of the forces of the main spring and the second sedative body spring.
Since the sedative body reverses its phase when passing through the resonance point, that is, the phase between the main mass vibration and the sedative body vibration is reversed, the resultant force is reduced in relation to the excessive increase in the resultant force. This is because the forces derived from the main spring and the second sedative body spring cancel each other out.

The fact that only springs that are damped by their inherent material damping are additionally used for force offsetting. Therefore, it is preferable that a rubber body with a strong phase angle of at least 8 ° is used as the main spring, and a rubber body with a weak phase angle of 4 to 6 ° is used as the sedative body spring.

Furthermore, it is advantageous if both sedative springs have different stiffness. In that case, the second sedative body spring has a higher rigidity than the first sedative body spring, the rigidity ratio is preferably 2: 1 and the total stiffness of both the sedative body springs is 25-75N. Advantageously, it is in the range of / mm.

In the case of an engine mount with the device described above, according to the invention, a pot-shaped housing is provided which is connected to the body of the motor vehicle, the upper part of which allows the engine of the motor vehicle via a bearing spring as the main spring. The central mount plate is supported and has a bolt-like extension projecting downward into the housing, and a sedative mass formed in the shape of a hollow cylinder through a first sedative-body spring in the bolt-shaped extension. Coupled, the lower end of the sedative mass is connected via a second sedative spring to a bolt projecting upward from the housing bottom.

In this case, it is preferable that the sedative body spring is formed in a ring shape, and the outer peripheral surface thereof is vulcanized and connected to the inner peripheral surface of the mass of the sedative body, and the inner peripheral surface thereof is vulcanized and connected to the mount bolt or the vehicle body bolt.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of an embodiment according to the present invention will be described in detail below with reference to the drawings.

The sedative device in FIG. 1 showing the prior art has already been described in detail at the outset.

The principle of the scheme according to the invention is shown in FIG. In that case, the main mass 1 passes through the main spring 4 and the foundation 5
Supported by. Here, the sedative mass 2 is arranged in parallel with the main spring 4. This sedative body mass 2 is connected to the main mass 1 via a first sedative body spring 6 and guides the generated force to the foundation 5 via a second sedative body spring 7. When the vibration directions of the main mass 1 and the sedative body mass 2 are the same, first, a large force is introduced to the foundation 5, and when passing through the resonance point of the sedative body, the main spring 4 and the second sedative body spring 7 form the foundation. This leads to a reduction in the resultant force and hence a reduction in the dynamic stiffness, since the forces introduced in 5 cancel each other out.

The principle shown in FIG. 2 is realized in the embodiment of the engine mount shown in FIG. 3, which will be described below. In that case, first, the pot-shaped housing 10
Is provided, which is rigidly connected via its bottom plate 11 to the body of the motor vehicle. A hollow cone-shaped bearing spring is fitted as a main spring 4 in the upper part of the housing 10, which supports an engine, shown diagrammatically as a main mass 1, via a central mounting plate 12.

The mount plate 12 has a bolt-like extension 13 which projects downward into the housing 10.
At its lower end, a first sedative body spring 6 formed in a ring shape.
The sedative body mass 2 formed in the shape of a hollow cylinder is connected via the. The sedative body mass 2 is connected at its lower end via a second sedative body spring 7 to a bolt 14 projecting upward from the housing bottom plate 11.

When the principle shown in FIG. 2 is realized, the sedative body mass 2 is excited by the movement of the main mass 1 via the first sedative body spring 6 and via the second sedative body spring 7. Force is guided from the housing bottom plate 11 to the foundation (not shown). The resultant force introduced into the vehicle body when passing through the resonance point of the sedative body 2 is reduced because the forces introduced from the main spring 4 and the second sedative body spring 7 cancel each other out. In that case, in order to utilize the material damping inherent in such a rubber spring for the force canceling action, a weakly dampening sedative body spring with a phase angle of 4-6 ° and a strong phase angle of 8-12 ° or more. It is preferable to combine it with the main spring 4 that attenuates.

Furthermore, it is expedient that the first sedative body spring 6 and the second sedative body spring 7 do not exhibit the same rigidity.
The sum of the stiffnesses of the first and second sedator springs, together with the sedator mass, determines the natural frequency of the sedator and is therefore not freely selectable. In that case, the smaller the rigidity of the second sedative body spring 7 that guides the force to the vehicle body, the smaller the force that is used for offsetting. Therefore, it is preferable that the second sedative body spring 7 has a higher rigidity than the first sedative body spring 6. In this case, in order to ensure that the sedative body has a natural resonant frequency of approximately 25 Hz with a sedative body mass of approximately 1 to 3 kg, this stiffness ratio is approximately 2: 1 and the sum of the stiffnesses of both sedative body springs is It has been found to be advantageous to be in the range 25-75 N / mm.

Therefore, in the correspondingly dimensioned mount with sedative bodies connected in parallel, there is a reduction in the forces directed to the motor vehicle at no-load rotation and thus a reduction in dynamic stiffness. However, this effect comes at the expense of increased force introduction at frequencies below the unloaded rotational frequency.

The overall course of the dynamic stiffness is shown diagrammatically with respect to frequency in FIG. For best performance, the sedative body should be tuned to the frequency where stiffness is sought to be minimized, i.e. to the no-load rotational frequency which is about 25 Hz for a four cylinder engine. As can be seen from FIG. 4, the sedative body has a resonance frequency corresponding to an almost no-load rotation frequency of 30 Hz or less, and is 20 below the no-load rotation speed.
The introduction of increased force in the Hz range is shown.

This disadvantage as a whole is such that, as this range of increased dynamic stiffness is only passed when starting the engine, before reaching the no-load rpm, and only occurs momentarily. It can be easily tolerated in order to improve the vibration isolation at no-load rpm of the engine.

[Brief description of drawings]

FIG. 1 is a principle diagram of a sedative device in the prior art.

FIG. 2 is a principle diagram of a soothing device according to the present invention.

FIG. 3 is a cross-sectional view of an engine mount formed with a sedative mass based on the principle of FIG.

FIG. 4 is a diagram of the dynamic rigidity of the engine mount in FIG.

[Explanation of symbols]

 1 Main Mass 2 Sedative Mass 4 Main Spring 5 Foundation 6 First Sedative Spring 7 Second Sedative Spring 10 Housing 11 Housing Bottom Plate 12 Mount Plate 13 Bolt 14 Bolt

Claims (8)

[Claims] 1. A device for frequency-selectively minimizing the dynamic spring stiffness of an elastomer mount, such as having a sedator for a given frequency range, with a main spring (4) supporting a main mass (1). The sedative mass (2) is connected in parallel, this sedative mass (2) is connected to the main mass (1) via the first sedative spring (6) and the second sedative spring (7) is connected. A device for frequency-selectively minimizing the dynamic spring stiffness of an elastomer mount, characterized in that it is connected to and supported by the foundation (5). 2. A rubber body having a strong damping of a phase angle of at least 8 ° is used as the main spring (4), and a rubber body having a weak damping of a phase angle of 4 to 6 ° is used as a sedative body spring (6, 7). The device according to claim 1, wherein 3. Device according to claim 1, characterized in that both sedative body springs (6, 7) have different stiffnesses. 4. Device according to claim 3, characterized in that the second sedative spring (7) has a higher rigidity than the first sedative spring (6). 5. Device according to claim 4, characterized in that the stiffness ratio is 2: 1. 6. Device according to claim 4, characterized in that the sum of the stiffnesses of both sedative body springs (6, 7) lies in the range 25 to 75 N / mm. 7. A pot-shaped housing (10) is provided which is connected to the body of an automobile, the upper region of which supports the engine (1) of the automobile through a bearing spring (4) as a main spring, the center of which is supported. The mounting plate (12) has a bolt-like extension (13) projecting downward into the housing (10) and is hollow in this bolt-like extension (13) via a first sedative spring (6). The sedative body mass (2) formed in a cylindrical shape is coupled, and the lower end of the sedative body mass (2) projects upward from the housing bottom (11) via the second sedative body spring (7). 7. An engine mount with a device according to any one of claims 1 to 6, characterized in that it is connected to the engine mount. 8. A sedative body spring (6, 7) is formed in a ring shape, the outer peripheral surface of which is the inner peripheral surface of the sedative body mass (2), and the inner peripheral surface thereof is a mount bolt (13) or a vehicle body bolt (1).
The engine mount according to claim 7, wherein the engine mount is vulcanized and connected to 4).