JPS61119832A - Power unit mounting device - Google Patents

Abstract

PURPOSE:To enable the transmission of vibration to be reduced over a wide frequency range by providing a means for changing the spring constant of a second elastic member to change the resonance frequency of a resonance system of the second elastic member. CONSTITUTION:When vibration of constant displacement is applied to the power unit side of a mounting device, a mass body 21 is vibrated by exciting force accompanying pressure rise in a chamber 24. Then, the mass body 21 is vibrated by its own inertia force in the reverse phase displacement Y falling behind the power unit side displacement X. The motion of the mass body 21 in the direction Y expands the chamber 24 to lower the pressure in the chamber 24. Thus, the vibration transmitting force transmitted to the mounting device is reduced to provide the low vibration transmitting ratio over a wide range.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mounting device for elastically supporting a power unit on a support body, and particularly to an improvement in a mounting device for a power unit that elastically supports a mass body in an intermediate portion.

(Prior art) Generally, a mounting device that seals a liquid inside secures a large damping force to damp the vibration of the power unit.
The purpose is to reduce the static-dynamic ratio of the spring constant (static-dynamic ratio - dynamic spring constant / static spring constant) to prevent vibration and noise.

As a conventional power unit mounting device of this type, one shown in FIG. 7 is known. Nissan Service Bulletin No. 442 No. 95N August 1956 In Fig. 7, the first plate member l is attached to the power unit or mounting bolt 2.
The second
The plate member 3 is attached to the power unit or the other side of the vehicle body by a mounting bolt 4. The plate member 6 is integrally attached to the plate member 1 via the diaphragm 6 by a caulking member 7,
In the space surrounded by these, an air chamber 8 and a liquid chamber 9 are formed with a diaphragm 6 in between.

The caulking member 7 and the plate member δ are connected by a circular support elastic body 10, and the support elastic body 1o, the plate member 5, and the plate member 8
The space surrounded by and is defined as a liquid chamber 11.

The liquid chamber 9 and the liquid chamber 11 are communicated through a ground ice pipe 12 fixed to the plate member 5.

This mounting device is used in such a manner that the relationship between the loss factor, the transmission characteristics, and the frequency is as shown in FIG. 8, and the portion of low vibration transmission is located at the most problematic frequency.

(Problem to be Solved by the Invention) However, in such a conventional power unit mounting device, if the vibration transmission of one frequency is set to be reduced, it cannot be applied to other frequencies. There has been a problem in that it can only be applied to vehicle sound and vibration phenomena mainly caused by (means for solving the problem). It is an object of the present invention to provide a power unit mounting device that can solve the problems, and to achieve this purpose, the power unit mounting device of the present invention uses a member for mounting on the power unit side, a member for mounting on the vehicle body side, and a member for mounting on the vehicle body. a first elastic member that connects the members; a mass body disposed between the two mounting members; a second elastic member that elastically supports the mass body between the two mounting members; and the second elastic member. The invention is characterized in that it is provided with means for making the spring constant of the spring variable.

(Function) By providing a means for varying the spring constant of the second elastic member in this way, it is possible to change the resonance frequency of the resonant thread in which the mass body is the mass and the second elastic member is the spring, over a wide frequency range. Transmission of vibration from the power unit to the vehicle body can be reduced.

(Example) The mounting device of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, the power unit side mounting member 10 consists of a frame 11, a plate member 12 caulked to one end of the frame 11, and plate members 13 and 14 caulked to the other end of the frame 11. is attached to the power unit side bracket 16 with a mounting bolt 15. The vehicle body side mounting member 17 is attached to a vehicle body side mounting plact 19 with a mounting bolt 18, and the vehicle body side mounting member 17 and the plate member 14 are connected by a cylindrical support elastic member 20. The mass body 21 has its side portion connected to the frame 11 via an elastic member 22, and its lower end connected to the plate member 18 via an elastic member 28. A sealed chamber 24 is formed by the plate member 13, the elastic member 23, the support elastic member 201, and the vehicle body side attachment member 17, and the chamber 24 accommodates a liquid. Further, the chamber 25 surrounded by the frame 11, the plate member 12, the plate member 18, and the elastic member z8 is an air chamber, and the pressure introduction port 2 communicating with the inside of the chamber 25 is an air chamber.
Air is supplied and discharged from 6 through the connecting pipe 27, and a predetermined air pressure is applied. 86 is an air pressure measuring device in the chamber 25.

The mechanism for controlling the air pressure within the chamber 25 is constructed as shown in FIG. 28 indicates the main body of the mounting device, and the connecting pipe 27 has a supply pulp 29 and a discharge pulp 8.
Concatenate with 0. A reservoir tank 81 is connected to this supply pulp 29, and a near compressor δ2 is connected to the reservoir tank 81. 88 is the relief pulp of the reservoir tank 81. 84 is the control unit rar
) A pressure signal sent from a pressure sensor (not shown) provided in the mounting device main body 28 and an engine rotation signal sent from a rotation sensor (not shown) provided in the engine 85 are input, outputs a supply signal and a discharge signal.

Next, the effect will be explained. When the vehicle body side of this mounting device is fixed and the power unit side is vibrated with a constant displacement, the mass body 21 is At this time, the mass body 21 is vibrated with a phase displacement Y in the opposite direction, lagging behind the displacement x of the power unit jlA due to its own inertia force or the like. Movement of the mass body 21 in the Y direction expands the chamber 24 and moves in a direction that lowers the pressure within the chamber 24. Therefore, the vibration transmission force transmitted from the power unit to the mounting device can be reduced.

The mass body 21 has a resonance point at a certain frequency (fn) and when it resonates, X and Y are in opposite phase to each other, so in the region below the resonance frequency, the vibration transmission force of the entire mounting device gradually decreases as it approaches the resonance frequency. do. Thereafter, as the vibration transmitted from the power unit to the mounting device passes through the resonance frequency and the phase of the mass body 21 with respect to X changes, the transmitted force gradually increases, reaches a maximum value, and then converges to a constant value. When this characteristic is measured with respect to the dynamic spring constant while keeping the resonance frequency of the mass body 21 at a constant frequency, the result is as shown in FIG. 8. When the loss factor and vibration transmission characteristic are measured, the result is as shown in FIG.

The mounting device of the present invention has a resonance frequency of the mass body +
In this embodiment, the resonance frequency of the mass body 21 is varied by controlling the spring constant of the elastic part 2δ. There is. That is, the spring constant of the elastic member 28 is controlled in two stages by the air pressure within the chamber 25.

When compressed air is not supplied to the chamber 25 (open to the atmosphere), the mass body 21 vibrates freely due to the small spring constant of the second elastic body 22 that supports it, causing resonance on the low frequency side. Therefore, the transfer characteristic (dynamic spring constant) reaches its minimum around 20 H2, as shown by the solid line in FIG. 4, and then gradually increases. In addition, when compressed air is supplied, the mass body 21 is replaced by the second elastic body 22.
Since the spring constant of becomes large, resonance cannot be caused by itself, and the mass body z1 produces an effect as a mass damper,
The transfer characteristics are as shown in Fig. 4. Therefore, the transfer characteristic maintains a substantially flat transfer characteristic up to a resonance point around 80 Hz, and then increases and decreases. Specifically, when these transfer characteristics are applied to countermeasures for the problem of sound and vibration phenomena in vehicles, the resonant frequency (fIHz) when compressed air is not supplied corresponds to the idling vibration of a vehicle equipped with a four-cylinder engine, and compressed air is If the resonant frequency (f, H2) when supplied is set to the rotation speed at which muffled noise occurs at medium speeds, the force transmitted from the power unit to the vehicle body when this phenomenon occurs will be greatly reduced, and the sound and vibration performance against this phenomenon will be improved. do. Control regarding supply and discharge of compressed air is performed by a control unit 84 shown in FIG. 2 using an engine rotation signal and a mounting internal pressure signal as judgment signals. The control unit detects that the second-order component of engine rotation increases from the frequency below f8H2 in
, H2, it sends a signal to open the supply pulp to supply compressed air to the mounting body. Then, it is detected by a signal from the air pressure detector 86 (see FIG. 1) that the pressure within the mounting device has reached the set pressure, and the supply of compressed air is stopped. engine rotation'
The 22nd order product decreases from frequencies above f8H2, and f,H
When the signal corresponding to 2 is input, it sends a signal to open the discharge pulp to discharge the pressure in the chamber 25. By controlling in this way, this mounting device can obtain the characteristics shown by the solid line in FIG. 5, and can obtain a low imaging transmissibility over a wide range.

FIG. 6 is a diagram showing another embodiment of the present invention.

This embodiment uses the fluid within the orifice 65 as the mass body. In FIG. 6, the power unit side mounting member consists of an annular plate member 40 and a plate member 41, and is attached to a mounting bracket 48 to the power unit by bolts 42.
It is installed on. A diaphragm 44 and a partition plate 45 are sandwiched between plate members 40 and 41, and an air chamber 46 and a liquid chamber 4 are formed.
form 7. The mounting members on the vehicle body side are a plate member 48 and a frame body 49.
It consists of platen 5 for installation on the vehicle body side with bolts 50.
It is installed on 1. The first elastic member 52 is baked and bonded at both ends to the plate members 40 and 48, respectively, and the second elastic member 53 is baked and bonded to the inside of the frame 49, and the mass in the orifice is transferred through the liquid chamber. support indirectly. These elastic members 52 and 58 and the partition plate 45 allow the liquid chamber 5 to
form 4.

The bottom of the frame 49 is closed by a plate member 55, and a restraint plate 56 and a solenoid 57 for driving the restraint plate 56 are arranged inside the frame 49. The solenoid 57 is fixed to the plate member 55 and is driven and controlled by a control unit 59 based on a signal from an engine rotation speed sensor 58.

Next, the operation of the mounting device of this embodiment will be explained. In the mounting device of this embodiment, the engine rotation speed is detected by the engine rotation speed sensor 58, and the operation of the solenoid 67 is controlled by the control unit 59 based on the signal from the engine rotation speed sensor 58. When the control unit 59 controls the solenoid 57, it is determined that the engine is idling if the engine speed is 1000 rPm or less.
In order to cause resonance at a high frequency of 0 Hz or higher, the solenoid 57 is turned on and the restraining plate 56 is pressed against the lower surface of the elastic member 58 to harden the expansion spring element of the elastic member 5a. If the fluid in the orifice 55 is made into a mass body in this state, it will not resonate independently.Therefore, as shown by the dotted line in FIG. (20-26 for a 4-Kiryu engine tower vehicle)
Make sure the Hz ranges match. Further, if the engine speed is equal to or higher than IQOOrpm, it is determined that the engine shake is occurring, and the control unit 59 turns off the solenoid 67. Therefore, the expansion spring element of the second elastic member 58 becomes soft, and the fluid within the orifice 55 resonates as a mass body. In this state, as shown by the solid line in FIG. 4, the resonance frequency at which the vibration transmissibility of the mounting device becomes minimum is set to match the engine shake frequency (for example, 10 Hz). In this way, in this embodiment, the elastic member 58 has an expansion spring! ! IIg is changed to 02 stages by the restraining plate 56, thereby the orifice 5
The resonant frequency of the resonant system whose mass is the mass of the fluid in 5 is z
Both engine shake and idling vibration are reduced by changing the frequency in stages, and as in the above-described embodiment, it is possible to reduce the vibration generated in the power unit over a wide frequency range.

(Effects) As detailed above, the power unit mounting device of the present invention includes a member for mounting on the power unit side, a member for mounting on the vehicle body side, a first elastic member connecting the members for both mountings, and a first elastic member for connecting the two mounting members. The structure includes a mass body disposed between them, a second elastic member that elastically supports the mass body between the two mounting members, and means for making the spring constant of the second elastic member variable. Not only can it significantly reduce the vibration level of engine shake and idle vibration, which are problematic vibration phenomena in vehicles, but it can also reduce the vibration transmission rate over a wide range, making it a reliable tool for reducing various types of vibrations that occur in the power unit. It has the effect of improving the riding comfort of the car, the muffled noise, etc. 1, and can greatly improve the marketability.

[Brief explanation of the drawing]

1 is a sectional view showing the configuration of an embodiment of the power unit mounting device of the present invention, FIG. 2 is a diagram showing the configuration of the control mechanism of the mounting device of FIG. 1, and FIG. 8 is a sectional view of the mounting device of FIG. 1. A characteristic diagram showing the characteristics when the resonant frequency of the mass body is kept at a constant frequency in the device. Figure 4 is a characteristic diagram comparing the characteristics with the state in which pressure is applied to the air chamber of the mounting device shown in Figure 1. , FIG. 5 is a characteristic diagram showing the characteristics when the pressure in the air chamber of the mounting device shown in FIG. 1 is controlled according to the present invention, FIG. 6 is a sectional view showing the configuration of another embodiment of the present invention, and FIG. The figure is a sectional view showing the configuration of a conventional mounting device for a power unit of this type, and FIG. 8 is a characteristic diagram showing the characteristics of the mounting device of FIG. 7. 10...Power unit side mounting member 11...Frame body 12, 13.14...Plate member 15...Mounting bolt 16...Power unit side bracket 17...Vehicle side mounting member 18...Installation Bolt 19... Vehicle body side mounting bracket 20... Support elastic member 21... Mass body 22.
...Elastic member 28...Elastic member 24, 25
...Chamber 26...Pressure inlet 27...
Connection pipe 28... Mounting device main body z9... Supply pulp aO... Discharge pulp 31
...F-Hatank 9,82...Air compressor 33...Relief pulp 84...Control unit 35...Engine 86...
Air pressure detector 40.41...Plate member 42...
・Bolt 48...Mounting bracket 44...Diaphragm++5...Partition plate 46...Air chamber h7...Liquid chamber 48...Plate member 49・
...Frame body 50...Bolts 51...Brackets 52, 58...Elastic members 54...Liquid chamber Patent applicant Nissan Motor Co., Ltd. Fig. 1 B Fig. 2 Fig. 3 4 figure 20 40 60 course 100 order l
Y number (H value) Figure 5 Figure 6

Claims (1)

[Claims] 1. A power unit side mounting member, a vehicle body side mounting member, a first elastic member connecting these two mounting members, a mass body disposed between the two mounting members, and this mass body. A mounting device for a power unit, comprising: a second elastic member elastically supported between the two mounting members; and means for varying a spring constant of the second elastic member. 2. The power unit mounting device according to claim 1, wherein the spring constant of the second elastic member is controlled by compressed air from outside the mounting device. 3. The power unit mounting device according to claim 2, wherein the supply and discharge of the compressed air is controlled by an engine rotation signal. 4. A patent claim in which the spring constant of the second elastic member is switched in two stages, the first resonance frequency is set to the idle rotation speed of a four-cylinder engine, and the next resonance frequency is set to the engine rotation speed that generates a medium-speed muffled sound. A mounting device for a power unit according to items 1, 2, and 3.