Fluid-sealed engine mount of vehicle

A fluid-sealed engine mount includes a variable orifice whose cross-section is changed according to a magnitude of engine vibration, thereby keeping a damping performance substantially unchanged at a time of large displacement vibration of an engine as compared to a time of small displacement vibration of the engine.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. § 119(a) the benefit of Korean Patent Application No. 10-2019-0042246 filed on Apr. 11, 2019, the entire contents of which are incorporated herein by reference.

BACKGROUND

(a) Technical Field

The present disclosure relates to a fluid-sealed engine mount, more particularly, to the fluid-sealed engine mount that controls behavior of an engine mounted on a vehicle body and insulates vibration.

(b) Description of the Related Art

Generally, an engine mount is used in a vehicle to control the behavior of an engine and to insulate vibration. A conventional engine mount applies a fluid-sealed engine mount in order to insulate engine vibration appearing in a wide frequency band.

In the conventional fluid-sealed engine mount, a flow path for fluid movement is disposed between an upper liquid chamber and a lower liquid chamber, in addition to an insulator for vibration insulation, and the vibration of the engine is absorbed by the insulator and the fluid.

Since across-sectional area and a length of the flow path is set in the conventional fluid-sealed engine mount, a large difference in damping force and frequency may occur for each vibration magnitude of the engine. Generally, in the conventional fluid-sealed engine mount, as the magnitude of the vibration increases, the damping force reduces and the frequency increases.

The conventional fluid-sealed engine mount can attenuate vertical vibration of the engine in a predetermined frequency range to control the engine vibration during traveling, and the damping performance varies according to the magnitude of vibration input to the engine mount. Particularly, there is a problem in that in the conventional fluid-sealed engine mount, the damping performance with respect to large displacement behavior (movement) in which the engine moves in the vertical direction of the vehicle is relatively lower than the damping performance with respect to a bottom displacement behavior of the engine. Specifically, in the fluid-sealed engine mount, the pressure acting on the fluid sealed inside the engine mount at the time of the large displacement behavior of the engine is increased as compared with small displacement behavior thereof, and therefore, since the flow rate of the fluid increases, frictional resistance caused by the flow of the fluid in the flow path (orifice) in which the fluid flows becomes large. There is a problem in that in the fluid-sealed engine mount, the flow of the fluid is reduced as the frictional resistance increases, and as a result, the damping force for engine vibration is reduced.

That is, the conventional fluid-sealed engine mount requires a relatively large damping force at the time of the large displacement behavior of the engine as compared to the small displacement behavior of the engine, and there is a problem in that the damping force at the large displacement behavior of the engine is further reduced as compared to the small displacement behavior of the engine.

SUMMARY

The present disclosure provides a fluid-sealed engine mount having a variable orifice whose cross-section is changed according to a magnitude of engine vibration, thereby keeping a damping performance substantially unchanged at a time of large displacement vibration of an engine as compared to a time of small displacement vibration of the engine.

Therefore, the present disclosure provides a fluid-sealed engine mount including an insulator formed at the lower portion of a mount core connected with an engine to insulate vibration by the movement according to the engine vibration; a membrane unit disposed under the insulator to separate an upper liquid chamber formed inside the insulator from a lower liquid chamber formed under the upper liquid chamber; a contact rib provided at the lower portion of the insulator to be disposed in a state contacting the surface of the membrane unit, and having a contact width contacting the surface of the membrane unit changed according to the movement of the insulator; and a variable orifice formed at the lower portion of the insulator to enable the fluid flow between the upper liquid chamber and the lower liquid chamber, and having a cross-section area changed according to the contact width of the contact rib by being disposed adjacent to the contact rib.

The engine mount has the following characteristics.

As the insulator is pressed downward by the engine vibration, the contact width of the contact rib contacting the surface of the membrane unit can be increased. As the insulator is pulled upward by the engine vibration, the contact width of the contact rib contacting the surface of the membrane unit can be reduced.

A bending part contacting the surface of the membrane unit in a state bent toward the upper liquid chamber can be provided at the lower end portion of the contact rib. The lower portion of the insulator can be bonded to the inner circumferential surface of an outer pipe unit that is fixed to a vehicle body through a mount bracket. A fixed rib disposed at the outside of the contact rib to surround the variable orifice can be provided at the lower portion of the insulator, and the fixed rib can be fixed to the inner circumferential surface of the outer pipe unit in a state stacked on the surface of the membrane unit. A first fluid flow hole for fluid flow between the upper liquid chamber and the variable orifice can be formed at one side of the contact rib. A second fluid flow hole for fluid flow between the lower liquid chamber and the variable orifice can be provided at one side of the membrane unit. The variable orifice is formed in an annular shape along the circumferential direction of the insulator, and maintained at a certain length without changing according to the movement of the insulator.

The membrane unit can be composed of a membrane plate press-fitted into the outer pipe unit; and a membrane disposed at the central portion of the membrane plate to be elastically deformed by the pressure difference between the upper liquid chamber and the lower liquid chamber. The outer pipe unit can be composed of a first outer pipe provided with a support end formed by stacking the inner circumferential surface contacted with the lower portion of the insulator and the upper surface of the membrane plate; and a second outer pipe having the first outer pipe and the membrane plate press-fitted therein to be vertically disposed.

The mount bracket can include a casing part to which the outer pipe unit is press-fitted and fixed, and the outer pipe unit can enter the casing part until the upper end of the insulator contacts the inner surface of the casing part. The upper end of the insulator is lowered by the load due to the weight of the engine when the mount core is connected with the engine to be separated from the inner surface of the casing part.

In the fluid-sealed engine mount according to the present disclosure, it is possible to increase the damping force at the time of the large displacement vibration of the engine as compared to at the time of the small displacement vibration of the engine by changing the cross-section of the variable orifice according to the magnitude of engine vibration, thereby securing the damping rate of the same level with respect to the small displacement vibration and the large displacement vibration of the engine.

The above and other features of the disclosure are discussed infra.

In the drawings, reference numbers refer to the same or equivalent sections of the present disclosure throughout the several figures of the drawing.

DETAILED DESCRIPTION

Further, the control logic of the present disclosure may be embodied as non-transitory computer readable media on a computer readable medium containing executable program instructions executed by a processor, controller or the like. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards and optical data storage devices. The computer readable medium can also be distributed in network coupled computer systems so that the computer readable media is stored and executed in a distributed fashion, e.g., by a telematics server or a Controller Area Network (CAN). A fluid-sealed engine mount requires a damping force greater than when the small displacement behavior of an engine occurs in order to keep the damping performance (damping rate) of the engine mount regardless of the magnitude (amplitude) of engine vibration, when a relatively large amplitude vibration is input due to occurrence of the large displacement behavior (movement) of the engine.

The damping force w of a fluid-sealed engine mount can be calculated as in the following Equation 1.
ω2=(2πf)2=(a×Cv)/(ρ×l)  Equation 1

Herein, ω refers to a damping force of the fluid-sealed engine mount, f refers to a frequency of input vibration, a refers to a cross-sectional area of an orifice for moving (an upper liquid chamber↔a lower liquid chamber) fluid sealed in the engine mount, Cvrefers to volume stiffness, ρ refers to the density of fluid, and l refers to the length of the orifice.

As can be seen from Equation 1, the damping force ω of the fluid-sealed engine mount is proportional to the cross-sectional area a of the orifice and inversely proportional to the length l of the orifice.

In particular, the fluid-sealed engine mount according to the present disclosure is configured to include a variable orifice whose cross-sectional area is changed according to a magnitude of engine vibration. Since the fluid-sealed engine mount applies the variable orifice, it is possible to increase the damping force at a time of a large displacement behavior as compared to a time of a small displacement behavior of the engine, and therefore, it is possible to keep the damping performance at substantially the same level as the time of the small displacement vibration of the engine.

Hereinafter, an engine mount of the present disclosure will be described with reference to the accompanying drawings.

As illustrated inFIGS. 1 and 2, a fluid-sealed engine mount100of the present disclosure is configured to include an insulator110, a membrane unit130, a variable orifice116, etc.

The insulator110is integrally provided in a mount core120connected to the engine, is made of rubber having strong elasticity, and can be vulcanized and molded under the mount core120. The mount core120can be coupled to the engine through a bolt member122and move integrally with the engine. The insulator110is connected to the engine by the mount core120and moves according to the engine vibration inputted through the mount core120. The insulator110insulates the vibration while moving according to the vibration of the engine. The engine vibration can occur in the vertical direction of the vehicle.

The upper portion of the insulator110can be formed to be bonded to the mount core120to surround the mount core120, when the insulator110is molded. The lower portion of the insulator110can be formed to surround an upper liquid chamber162in which the fluid is sealed. In addition, a contact rib112, a fixed rib114, and the variable orifice116can be formed under the insulator110.

The contact rib112and the fixed rib114are formed to surround the variable orifice116. The contact rib112can be disposed inside the variable orifice116and the fixed rib114can be disposed outside the variable orifice116. The contact rib112and the fixed rib114can be disposed in a state stacked on the upper surface of the membrane unit130. The lower surface of the fixed rib114can be stacked in a state contacting the upper surface of the membrane unit130.

The lower end portion of the contact rib112can be stacked on the upper surface of the membrane unit130in a state bent toward the upper liquid chamber162. The lower end portion of the contact rib112slidably contacts the surface of the membrane unit130. When the engine vibration is input to the mount core120, the contact rib112vertically moves by interlocking with the behavior of the insulator110. The movement amount and the movement direction of the contact rib112can be changed according to the magnitude and the direction of vibration input from the engine. The contact width (the contact amount) contacting the surface of the membrane unit130can be changed according to the movement amount and the movement direction thereof. The contact rib112can be further bent or unfolded according to the magnitude and the direction of the input vibration. The initial contact amount (i.e., the initial contact width) (see a inFIG. 2) of the contact rib112that contacts the surface of the membrane unit130before the vibration is transferred to the mount core120can be referred to as a first contact value, and the first contact value can be set to a certain value. The contact width of the contact rib112that contacts the surface of the membrane unit130is greater than the first contact value, when the engine vibration is input to the mount core120in the direction of pressing and compressing the insulator110and the contact width of the contact rib112can be increased in proportion to the magnitude of the engine vibration. The first contact value can be set based on a state where the upper end of the insulator11has been separated from the inner surface of a casing part172of a mount bracket170by the load according to the weight of the engine connected to the mount core120. The insulator110can be inserted into the casing part172until the upper end of the insulator110contacts the inner surface of the casing part172, in an assembled state before the mount core120is connected with the engine (seeFIGS. 6B and 6C). The upper end of the insulator110is separated at a certain interval from the inner surface of the casing part172by the load of the engine, in an assembled state where the mount core120has been connected with the engine (seeFIG. 2). When the engine mount100is mounted between the vehicle body and the engine, the load according to the weight of the engine connected to the mount core120acts on the insulator110.

The contact rib112is disposed between the upper liquid chamber162and the variable orifice116, and formed to be deformed according to the magnitude of vibration input to the mount core120. The contact rib112is disposed at a position to surround the lower portion of the upper liquid chamber162under the insulator110, is disposed outside the upper liquid chamber162, and inside the variable orifice116. When the insulator110vertically moves by the vibration, the contact rib112also moves vertically. As the contact rib112moves downward, the contact rib112can be bent more and more, and as the contact rib112moves upward, the contact rib112can be gradually unfolded and restored.

Specifically, the contact rib112can be integrally molded with the insulator110to be disposed under the insulator110. The contact rib112can be molded by bending the lower portion thereof toward the center of the membrane unit130. The bent lower portion of the contact rib112can be referred to as a bending part112a. The bending part112acan be deformed according to the behavior of the contact rib112.

The fixed rib114is supported by an outer pipe unit140disposed outside the lower portion of the insulator110and the membrane unit130disposed under the insulator110. The fixed rib114can be supported by stacking the lower surface of the fixed rib114on the membrane unit130, in a state where the outer circumferential surface there has been bonded to the inner circumferential surface of the outer pipe unit140. This fixed rib114can be maintained in its original shape by the outer pipe unit140and the membrane unit130even when the insulator110and the contact rib112are deformed by the input vibration. That is, the fixed rib114can be maintained in a constant shape regardless of whether the insulator110and the contact rib112are deformed.

The variable orifice116is a flow path for fluid flow and movement between the upper liquid chamber162and a lower liquid chamber164. As illustrated inFIGS. 1 to 3, the variable orifice116is disposed between the contact rib112and the fixed rib114. The variable orifice116can be provided at the lower portion of the insulator110with the lower end thereof opened. The opened lower end of the variable orifice116can be sealed by the membrane unit130disposed under the insulator110. That is, the variable orifice116can be disposed between the insulator110and the membrane unit130.

The cross-sectional area of the variable orifice116can be changed according to the movement of the insulator110. This is because when the upper portion of the insulator110moving with the mount core120is vertically moved, the contact rib112formed at the lower portion of the insulator110also move vertically and is deformed. As the variable orifice116is disposed adjacent to the contact rib112, the cross-sectional area for fluid flow can be changed by deformation of the contact rib112. The contact rib112slides on the surface of the membrane unit130when being deformed by interlocking with the behavior of the insulator110. The variable orifice116can be formed in an annular shape along the circumferential direction of the membrane unit130and the circumferential direction of the insulator110. The circumferential length of the variable orifice116is constantly maintained at all times regardless of whether the insulator110is moved.

Meanwhile, the membrane unit130can be configured to separate the upper liquid chamber162formed inside the lower portion of the insulator110and the lower liquid chamber164disposed under the upper liquid chamber162. The membrane unit130can include an outer membrane plate134and an inner membrane132. The membrane plate134can be formed in a flat plate shape having the central portion opened. The membrane132can be bonded to the central portion of the membrane plate134to seal the central portion of the membrane plate134. The membrane132can be integrally fixed by being formed and vulcanized at the central portion of the membrane plate134. The membrane132can be elastically deformed by a fluid pressure difference between the upper liquid chamber162and the lower liquid chamber164, and such deformation can partially insulate the engine vibration.

The membrane plate134can be press-fitted into and fixed to the outer pipe unit140. The membrane plate134is disposed between the upper liquid chamber162and the lower liquid chamber164in a state fixed to the inside of the outer pipe unit140. A second fluid flow hole134afor fluid flow between the variable orifice116and the lower liquid chamber164can be formed at one side of the membrane plate134. A first fluid flow hole112bcan be formed at one side of the contact rib112. The first fluid flow hole112benables the fluid flow between the upper liquid chamber162and the variable orifice116. The first fluid flow hole112band the second fluid flow hole134acan be spaced at a certain interval apart from each other with respect to the circumferential direction of the variable orifice116. A block part118for blocking the fluid flow can be provided at a position on the variable orifice116corresponding between the first fluid flow hole112band the second fluid flow hole134a. The fluid moving between the upper liquid chamber162and the lower liquid chamber164flows along the circumferential direction of the variable orifice116due to the block part118, when passing through between the first fluid flow hole112band the second fluid flow hole134a.

The lower liquid chamber164can be sealed by a diaphragm150disposed under the membrane plate134. The diaphragm150can be assembled and fixed between the membrane plate134and the outer pipe unit140. The diaphragm150can be elastically deformed to support the sealed state of the lower liquid chamber164when fluid movement occurs between the upper liquid chamber162and the lower liquid chamber164.

The outer pipe unit140can be composed of an inner first outer pipe142and an outer second outer pipe144. The first outer pipe142can be press-fitted into and fixed to the second outer pipe144. The first outer pipe142can be formed to have the vertical length (the vertical height) shorter than the second outer pipe144by a certain length. Therefore, the lower end (or the lower surface) of the first outer pipe142supports the membrane plate134that is press-fitted into the second outer pipe144and can become a support end142afor fixing the position of the membrane plate134. The membrane plate134can be stacked on the support end142ato be disposed under the first outer pipe142. Then, a curling part144afor supporting the diaphragm150can be provided at the lower end of the second outer pipe144. The inner circumferential surface of the first outer pipe142can be bonded to the lower portion of the insulator110.

Herein, an assembly procedure of the fluid-sealed engine mount configured as described above will be described with reference toFIGS. 4 to 6C.

As illustrated inFIG. 4, the first outer pipe142is first press-fitted into the second outer pipe144to constitute the outer pipe unit140. Next, the mount core120and the outer pipe unit140are set in the mold for molding the insulator110, and the resin for insulator is injected into the cavity for insulator of the mold to mold the insulator110. The bending part112aof the contact rib112is formed in a state that has been slightly bent toward the upper liquid chamber162at the time of molding the insulator110, but the insulator110including the contact rib112is molded with an elastic material such as rubber, and therefore, the contact rib112is elastically deformed, such that the insulator110can be detached from the mold without the locking of the contact rib112.

Then, as illustrated inFIGS. 5A and 5B, the membrane unit130is press-fitted into the outer pipe unit140. The membrane unit130is press-fitted into the second outer pipe144until the surface of the membrane plate134is in closely contact with the support end142aof the first outer pipe. At this time, the contact rib112and the fixed rib114facing the upper surface of the membrane plate134are stacked on and contact the upper surface of the membrane plate134.

Then, as illustrated inFIG. 5C, the diaphragm150is stacked under the membrane plate134, and the lower end portion of the second outer pipe144is curled toward the diaphragm150. The curled end portion (i.e., the curling portion) of the second outer pipe144is supported so that a sealing part152of the diaphragm150is in close contact with the lower surface of the membrane plate134. The sealing part152can be formed to be protruded from the edge of the diaphragm150, and can be formed to extend along the circumferential direction of the diaphragm150.

Subsequently, as illustrated inFIGS. 6A and 6B, the outer pipe unit140is press-fitted into and fixed to the casing part172of the mount bracket170. The outer pipe unit140is pressurized and enters the casing part172until the upper surface of the insulator110contacts the upper inner surface of the casing part172. At this time, as illustrated inFIG. 6C, the upper portion of the mount core120penetrates the upper end of the casing part172to be coupled with a dust cover124. The dust cover124is disposed above the casing part172to cover the opened upper end of the casing part172.

The mount bracket170includes a bracket part174formed integrally with the casing part172, and the bracket part174can be mounted and fixed to the vehicle body or a chassis frame of the vehicle, etc.

As illustrated inFIGS. 7A and 7B, in the fluid-sealed engine mount100configured as described above, when the insulator110is vertically moved by the input vibration, the cross-sectional area of the variable orifice116surrounded by the contact rib112and the variable orifice116is changed. When the insulator110vibrates upward, the insulator110is pulled upward and tensioned, such that the cross-sectional area of the variable orifice116can be increased. When the insulator110vibrates downward, the insulator110is pressurized downward and compressed. When the insulator110is compressed, the contact rib112is pressed downward, such that the sectional area of the variable orifice116can be reduced. When the contact rib112is deformed by being pulled or pushed, the bent lower end portion (i.e., the bending part) of the contact rib112, which is in contact with the surface of the membrane plate134, is also deformed. When the contact rib112is pressed to the membrane unit130side, the lower end portion of the contact rib112can be further bent to enlarge the bending part112a. When the contact rib112is pulled toward the mount core side, the lower end portion of the contact rib112can be unfolded to reduce the bending part112a. That is, the length of the bending part112acan be increased or reduced according to the deformation of the contact rib112. The bending part112acan slide on the surface of the membrane plate134when the contact rib112is deformed. When the bending part112aslides to the membrane132side, the cross-sectional area of the variable orifice116can be reduced. When the bending part112aslides to the outer pipe unit side, the cross-sectional area of the variable orifice116can be increased.

The cross-sectional area of the variable orifice116can be increased or reduced in proportion to the magnitude of vibration input to the mount core120. Therefore, when the maximum vibration in the direction of pulling the insulator110upward is input to the mount core120, the engine mount100has the maximum damping force. The damping force of the engine mount100can be reduced as the magnitude of the input vibration is reduced. The engine vibration is transferred to the vehicle body through the engine mount100when the engine moves downward. Therefore, when the engine mount100has the maximum damping force, the vibration input from the engine can be maximally insulated and minimized.

That is, the engine mount100can generate the damping force when the large displacement of the engine occurs greater than the damping force when the small displacement thereof. Therefore, when a relatively large vibration is input to the engine mount100, the damping performance (the damping rate) of the same level as that in the case where small vibration is input to the engine mount100can be maintained.

That is, the engine mount100can secure the damping rate of the same level at all times with respect to the same frequency band regardless of the amplitude of the input vibration by the increase or the decrease in the damping force for each amplitude of the input vibration. In addition, the engine mount100can minimize the excitation caused by insufficient damping force when traveling on a road surface having large unevenness.

Meanwhile, as illustrated inFIG. 8, when the fluid pressure difference between the upper liquid chamber162and the lower liquid chamber164becomes a predetermined threshold pressure or more, a minute crack (gap) through which fluid minutely passes is formed between the contact rib112and the membrane unit130, while the contact rib112is minutely lifted. The fluid pressure difference between the upper liquid chamber162and the lower liquid chamber164can be reduced to be smaller than the threshold pressure by the minute flow of the fluid. Therefore, when the fluid pressure difference is the threshold pressure or more, it is possible to prevent cavitation (joint) caused by the flow of fluid passing through the variable orifice116. When the fluid pressure difference is smaller than the threshold pressure, the contact rib112is in close contact with the upper surface of the membrane unit130again and the flow of the fluid between the contact rib112and the membrane unit130does not occur.

In addition, since the structure for separating the upper liquid chamber162and the lower liquid chamber164is simplified as compared to from the conventional fluid-sealed engine mount, the vertical height of the engine mount100is reduced and the manufacturing cost is reduced. In addition, since the vertical height of the engine mount100is reduced, the input point rigidity can be enhanced.

As described above, although the embodiments of the present disclosure have been described in detail, the claims of the present disclosure is not limited to the above-described embodiments, and various modifications and improvements by those skilled in the art using the basic concept of the present disclosure defined in the appended claims can also be included the claims of the present disclosure.