JPH0379832A - Engine mount - Google Patents

Abstract

PURPOSE: To assure the minimum elasticity of a dilatant element even when it becomes hard by setting rigidity of an auxiliary insulator mechanically serially connected to the dilatant element as an elasticity of an insulator of a mount connected in parallel multiplied by a specific number. CONSTITUTION: Rubber and metal bushes 27, 29 compose an elastic mount through which an engine support 11 is supported on a plunger 17 of a dilatant element 14, and an elasticity modulus of the rubber and metal bushes 27, 29 is a value of 2-5 times an elasticity of a rubber and metal mount 13 in representative design. Structure of this engine mount 10 corresponds to a mechanical equivalent circuit, and an auxiliary insulator 27 is serially connected to a parallel circuit of the dilatant element 14 and the rubber and metal mount 13. In an operation condition of a traveling vehicle to jump up rigidity to an excessive value by shearing of dilatant liquid and exceeding a critical value of shearing speed, the mount 10 has the minimum elasticity. This minimum elasticity is mainly decided by the elasticity modulus of the auxiliary insulator 27.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an engine mount for an automobile. [Prior Art] At least one insulator made of an elastic body that performs vibration isolation through elastic deformation at least within a limited frequency range of generated vibrations and mutually supports the vibrating mass, and the natural vibration of the mount/mass system. a dilant element provided to reduce the vibration amplitude within the range, in which a flow movement and/or shear movement is induced by the action of the relative movement of the vibrating mass, taking advantage of the viscous properties of the dilant liquid. , when the minimum value of shear (γ) (γkrit) and the threshold value (■s) of shear rate (γ) are exceeded in this dilant liquid, the vibration amplitude within the natural vibration range of the mount/mass system is reduced. , the dilant element has, on the one hand, a critical value of shear (γ) (γkrit) and a critical value of shear rate (÷) (■
s) is reached or exceeded, and on the other hand the characteristic minimum value (γkrit) of the shear (γ) of the shear of the dilant liquid associated with the excitation of high-frequency acoustic vibrations whose maximum amplitude is smaller than the vibration amplitude occurring within the natural vibration range. An engine mount designed to be larger than this value is already known from DE 34 05 907 A1. This known engine mount is for vibration-insulating support of the engine on the vehicle body or running frame of the vehicle, and is a rubber elastic insulator that provides an elastic connection between the engine and the vehicle body (in a mechanical parallel circuit). body and insulators
and a dilant element that serves to dampen the resonant increase in the amplitude of vibrations expected in the mass system. In a special embodiment, the dilant element of the known mount has a mount block that is rigidly connected to the vehicle body. The mounting block has a chamber filled with dilant fluid, into which a plunger connected to the engine projects. The plunger is inside a storage chamber filled with dilant liquid.
It provides an environment for the annular passage or annular gap. Within this annular gap, the dilant wave is periodically caused to flow as the plunger sinks. In that case, the shear γ and shear rate γ of the dilant liquid
It is exploited that when a critical value of . The dilant element is designed such that its stiffness jump occurs approximately within the natural vibration frequency of the insulator-mass system. This known mount furthermore provides that the shear critical value γkrit is not exceeded for vibration amplitudes below about 60 μm, and therefore even when the shear rate of the dielant fluid is above its critical value γ (this is true for high frequency, small amplitude ( acoustics) vibrations)
, no stiffness jump occurs and the vibration isolation properties are therefore determined by the insulator alone up to high frequencies. This means that the mount has good characteristics in terms of suppressing noise. Another engine mount that operates on the above-mentioned principle is also known from German Patent No. 37 38 716 A1. In the case of this known mount, the dilant element has, as a submersible body, flat shear plates extending parallel or approximately parallel to each other and similar flat shear plates extending parallel or approximately parallel to this. are doing. The former shear lamellas move together with masses connected to each other through an insulator, the latter shear lamellas move together with another mass, one shear lamina moving with the mass consists of two shear lamellas of the other moving with each other mass. It protrudes between the thin plates. The shear lamella that moves with one mass, such as the mass of the vehicle's engine, and the shear lamella that moves with another mass, such as the mass of the vehicle's body, are hingedly supported. This engine mount geometry allows for nevertheless favorable small dimensions when designing the dilant elements for the given high dynamic loads, so that critical shear and shear rates are achieved within the natural vibration range of the mount mass system. It is chosen so that the viscosity of the dilant increases slowly if the value is exceeded, and so that it must suffer from low dynamic stiffness up to high frequencies. However, the two known engine mounts mentioned above have at least the following drawbacks. When the dilant element reacts in the stiffening sense described above, i.e. when the engine vibrates with very low frequency and large amplitude relative to the vehicle body, this reaction of the dilant element produces a perceptible shock, which is transmitted to the driver. The driver feels uncomfortable at the very least, which worsens driving comfort. Furthermore, after the stiffness jump occurs, the mount no longer insulates but transmits the acoustic vibrations generated by the engine, i.e., vibrations between 20 Hz and 2 kHz, to the vehicle bodywork, causing a large continuous noise load on the vehicle. It has the disadvantage of causing [Problem to be Solved by the Invention] The object of the invention is to provide an engine mount of the type mentioned at the outset, with the aim of ensuring that even if the dilant element undergoes a stiffness jump and becomes, as it were, stiffened, the mount still has a minimum elasticity. The objective is to improve the system so that it does.

[Means to solve the problem]

According to the invention, this purpose is achieved by mechanically connecting in series with the dilant element an auxiliary insulator whose stiffness is equal to or less than the modulus of elasticity of the insulator of the mount connected in parallel to the dilant element. This is achieved by ~5 times the value. The mechanical series circuit of the auxiliary insulator and the dilant element according to claim 2 is paralleled to the insulator of the mount, or according to claim 3 the auxiliary insulator is connected to the insulator of the mount and the dilant element. By means of an auxiliary insulator provided in such a way that it is connected in series in a mechanical parallel circuit with the element,
In both cases, a certain minimum elasticity of the engine mount according to the invention is maintained. In the first case, the total elastic modulus corresponds to the sum of the elastic moduli of both insulators, and in the latter case it is determined by the elastic modulus of the auxiliary insulator. [Effects of the Invention] According to the present invention, a sufficiently good vibration insulating effect can be achieved in the entire frequency range of acoustic vibrations mainly generated by engine vibrations, even when the dilant element itself is stiff or almost stiff. At the same time, the shock sensation associated with the reaction of the dilant element is reduced, and driving comfort is significantly improved. [Examples] The present invention will be described in detail below with reference to embodiments shown in the drawings. The engine mount 10 shown in FIG. 1 and described in detail later includes:
On a vehicle body 12 schematically showing a road vehicle, a vehicle engine, which is shown only as a part of the engine sabot 11, is attached.
It is used to insulate and support vibrations. This engine mount 10 comprises, in the case of a -M-shaped engine mount, a main insulator 13 in the form of a rubber-metal mount, a diluent element 14 with a pot-shaped housing 16 which is firmly attached to the bodywork 12 of the vehicle.
, and a plunger 17 which is rigidly connected to the engine-side metal portion 20 of the main insulator 13 or, as shown, is formed integrally therewith. The internal chamber 18 of the pot-shaped housing 16 of the dielant element 14 , which is closed on the upper side by the (bell-shaped) main insulator 13 , is divided by a diaphragm 19 into a lower chamber 18 and an upper chamber 18 . The outer edge of the diaphragm 19 is attached to the housing 16 and the inner edge to the plunger 17 in a hermetically sealed manner. Lower chamber 1 of internal chamber 18
8 is completely filled with dilant liquid, and the upper chamber 18
is closed on the upper side by a rubber-metal mount and a central region of the plunger 17, filled with air and with a compensating opening 2
1 to the atmosphere. The lower part 22 of the plunger 17, which is received by the lower chamber 18 filled with dilant liquid, is formed in the form of an inner plate. The width W of the annular gap 24 between the outer edge 23 of the plunger lower portion 22 and the inner wall surface of the cylindrical pot-shaped housing 16 is determined as follows. That is, when the engine 11 vibrates perpendicularly to the vehicle body 12, that is, when it vibrates in the direction of the double arrow 26, the annular gap 2
4, the shear critical value γkrit and the shear rate critical value γ
It is determined that when S is exceeded, the viscosity of the dilant fluid in the annular gap 24 becomes extremely high, whereby the plunger 17 is firmly connected to the housing 16 of the dilant element 14. Furthermore, the width W of the annular gap 24 is always set when the vibration frequency of the engine 11 relative to the vehicle body 12 is within the natural vibration frequency range of the insulator/mass system 11.12.13, typically within the frequency range of 5 to 10 Hz. , it is determined that a jump in rigidity of the mount 10 occurs based on the coupling between the plunger 17 and the housing 16. The structure of the engine mount 10 described above essentially corresponds to the structure of the engine mount with dilant elements known from DE 34 05 907 A1. In contrast to this known engine mount, the engine mount 10 in FIG. 1 is provided with another insulator 27 (hereinafter referred to as auxiliary insulator). In the embodiment shown, the engine 11 is supported elastically via this auxiliary insulator 27 on a mounting part known per se, which has a main insulator 13 and a dilant element 14 . In the embodiment shown, the auxiliary insulator 27 is designed as an elastic element of a rubber-metal bushing inserted into a hole 28 in the engine support 11. The central metal bushing 29 of this rubber-metal bushing is firmly connected to the central metal part 20 of the rubber-metal mount forming the main insulator 13 or to the plunger 17 of the dilant element 14. This rubber-metal bushing 27,29 is a resilient mount through which the engine support 11 is supported on the plunger 17 of the dilant element 14. This rubber
The elastic modulus of the metal bushings 27, 29 has a value of 2 to 5 times the elastic modulus of the rubber-metal mount 13 in typical designs. The structure of the engine mount 10 described above corresponds to the mechanical equivalent circuit shown in FIG. In operating conditions of the cart in which the stiffness jumps to excessive values by exceeding the critical value γkrit of the shear γ and the critical value γS of the shear rate γ in the dilant fluid, the mount 10 still exhibits a minimum elasticity. have. This minimum elasticity is now determined primarily only by the elastic modulus (elastic stiffness) of the ordinal insulator 27 and is therefore well defined. It should be noted that the auxiliary insulator 27 having the function described with reference to the embodiment of FIG. 1 can also be arranged between the dilant element 14 and the vehicle body 12. The engine mount 10 in FIG. 1 has its central axis extending vertically in the operating state! ! It is formed rotationally symmetrically with respect to 25. This engine mount 10 therefore exhibits neutral elastic behavior with respect to vibrations directed at right angles to its central axis 25, and the engine 11 exhibits a neutral elastic behavior with respect to vibrations directed at right angles to its central axis 25.
A stiffness jump occurs only for the vibration mode when the vibration movement is parallel to 5. The engine mount 30 shown in FIG. 3 differs from the engine mount 10 shown in FIG. 1, firstly in the shape of the dilant element 31, and secondly in the arrangement structure of the auxiliary insulator 32. In this embodiment, the auxiliary insulator 32 is a rubber-metal mount 13 forming the main insulator.
between the central metal part 20 of the engine mount 30 and the dilant element 31, a mechanical equivalent circuit as shown in FIG. 4 results for this engine mount 30. Here, a special series circuit of auxiliary insulator 32 and dilant element 31 is connected in parallel to main insulator 13 . In the engine mount 30 of FIG. 3, the same symbols are attached to the same functional parts as those of the engine mount 10 of FIG. 1, and the explanation of the structure and function of these parts will be omitted here. In the engine mount 30 of FIG. 3, the elasticity that still exists after the dilant element 31 has stiffened is determined by the sum of the elastic modulus of the main insulator 13 and the elastic modulus of the auxiliary insulator 32. In the illustrated embodiment, the diluent element 31 of the engine mount 30 has two shear elements 33,34. These shear elements 33, 34 are connected to the housing 1
6 includes the center axis 25 of the mount 30, and is arranged symmetrically with respect to a vertical center plane perpendicular to the plane of the paper. Its longitudinal center plane extends parallel to the longitudinal center plane of the vehicle in the advantageous position of use of the mount 30. The auxiliary insulator 32 is designed here as an elastic element of a rubber-metal bushing. This elastic element is attached to a downwardly projecting pin 36 in FIG. 3 of the central metal portion 20 of the rubber-metal mount 13 forming the main insulator. On the outer metal bushing 37, thin plate shear bodies 41, 42 are supported so as to be swingable about shafts 38, 39 extending parallel to the longitudinal axis of the vehicle. In the embodiment shown, these shearing bodies 41, 42 each have three flat shearing plates 43, 44° 45 whose planes are oriented relative to the pivot axis 38, 39. extending in parallel. As can be seen from FIG. 3, these thin plate-like shear bodies 41 and 42 are comb-shaped or three-pronged fork-shaped. In FIG. 3, a U-shaped thin plate-like shear body 49 is attached to a mount body 47, 48 arranged on the bottom 46 of the housing 16.
, 50 are the swing shafts 3 of the thin plate down shear bodies 41 and 42 on the upper side.
8.39 and is pivotably supported about an axis 52.53 extending parallel to the axis 52.53. Similarly, the shear thin plates 54 and 56 formed in a flat plate shape are connected to the upper thin plate shear bodies 41 and 4.
The two shear plates 43, 44 of 2 project between 44° and 45°, in which case, in the illustrated rest position of the mount 30, the shear plates are arranged equidistant from each other. The shear type 57, 58, which is filled with dilant liquid and has an approximately rectangular cross section, has an outer shear thin plate 43.
45 and end walls (not shown) connecting them to each other. These new models 5
7, 58 are elastic bellows 5961 extending between the upper thin plate-like shear bodies 41, 42 and the mount body 5253;
The inner chamber 18 of the housing 16 is closed in a liquid-tight manner. Thin plate-like shear body 41.4 having the above-described shape and arrangement structure
The engine mount 30 with 2 and 49.51 is
When the engine 11 and the vehicle body 12 move relative to each other along the vertical longitudinal axis 25 of the mount 30 and when the engine 11 and the vehicle body 12 move relative to each other parallel to the longitudinal axis of the vehicle, the dilant element 31 is renewed. It has the property of stiffening in relation to the response of elements 33,34. On the other hand, when the engine 11 vibrates in the lateral direction of the vehicle relative to the vehicle body 12, the engine mount 30 maintains its elasticity even if the vibration amplitude is large. Note that the mount 10 in FIG. 1 can also be realized by a dilant element as described with reference to FIG. 3. Conversely, the mount 30 described with reference to FIG. 3, which corresponds to the isochoric circuit of FIG. 4, can also be realized with the dilant element 14 described with reference to FIG. Furthermore, it is of course also possible to use other elastic elements instead of rubber-metal bushings to realize the auxiliary insulation 27, 32, such as, for example, leaf springs, coil springs or disc springs.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an engine mount according to the invention, FIG. 2 is a mechanical equivalent circuit diagram of the engine mount in FIG. 1, and FIG. 3 is a sectional view of different embodiments of the engine mount according to the invention. FIG. 4 is a mechanical equivalent circuit diagram of the engine mount in FIG. 3. 10...Engine mount, 11...Engine support, 12...Vehicle body, 13.
... Insulator, 14... Dilant element, 16... Housing, 27... Insulator, 30... Engine mount, 31... Dirant element, 32... Insulator.

Claims (1)

[Claims] 1. At least one insulator consisting of an elastic pair that performs a vibration insulating action by elastic deformation at least within a limited frequency range of generated vibrations and mutually supporting a vibrating mass, and a mount/mass system. and a dilant element provided to reduce the vibration amplitude within the natural vibration range of the
Using the viscous properties of the dilant fluid, which causes flow motion and/or shear motion in this dilant element by the action of the relative motion of the vibrating mass, the minimum value of shear (γ) (γkrit) and the shear rate (■ ) when the threshold value (■s) is exceeded,
The vibration amplitude within the natural vibration range of the mount-mass system is reduced, and its dilant elements, on the one hand,
The critical value of shear (γ) (γkrit) and the critical value of shear rate (γ) (■s
) is reached or exceeded, and on the other hand the characteristic minimum value (γkrit) of the shear (γ) is the value of the shear of the dilant liquid associated with the excitation of high-frequency acoustic vibrations whose maximum amplitude is less than the vibration amplitude occurring within the natural vibration range. Dilant elements (
14, 31), an auxiliary insulator (27, 32) is mechanically connected in series, and the rigidity of this auxiliary insulator (27, 32) is a mount connected in parallel to the dilant element (14, 31). An engine mount characterized in that the elastic modulus of (10, 30) is 2 to 5 times the elastic modulus of the insulator (13). 2. The mechanical series circuit of the auxiliary insulator (32) and the dilant element (31) is connected in parallel to the insulator (13) of the mount (30). Engine mount. 3. Engine mount according to claim 1, characterized in that the auxiliary insulator (27) is connected in series in a mechanical parallel circuit of the insulator (13) and the dilant element (14). 4. The auxiliary insulator (27) is a rubber/metal bush (27,
forming the elastic element of the rubber-metal bushing (27)
, 29) is firmly connected to the central metal part (20) of the insulator (13) formed as a rubber, metal mount, and the elastic element (27) is inserted into the hole of the engine support (11). The engine mount according to claim 3, characterized in that the engine mount is firmly fitted into the engine mount (28). 5. Engine mount according to claim 3, characterized in that the auxiliary insulator (27) is arranged between the housing (16) of the dilant element (14) and the vehicle body (12). 6. Claim characterized in that the auxiliary insulator (32) is arranged between the central metal part (20) of the rubber-metal mount forming the insulator (13) and the dilant element (31). Engine mount described in 2. 7. Engine according to claim 2, characterized in that the auxiliary insulator (32) is arranged between parts of the housing (16) of the dilant element (31) or of the mount (30) rigidly connected thereto. mount. 8. Modulus of elasticity of auxiliary insulators (27, 32) and main insulator (1
8. The engine mount according to claim 1, wherein the ratio of 3) to the elastic modulus is determined to be 2 to 3, preferably 2.