Hydraulic Mount and Motor Vehicle Having such a Hydraulic Mount

Abstract

The invention relates to a hydraulic mount (2), comprising a supporting spring (36), a working chamber (4), which is at least partially surrounded by the supporting spring (36) and is filled with a hydraulic fluid, an equalization chamber (6), a hydraulic mount (8), which is arranged between the working chamber (4) and the equalization chamber (6), a throttle channel (10) for the exchange of hydraulic fluid, which throttle channel is formed between the working chamber (4) and the equalization chamber (6), a control membrane (12), which is designed to change a working chamber volume (14) of the working chamber (4), and an actuator (16) for deflecting the control membrane (12), wherein the hydraulic mount (2) has a control channel (24), which .sup.40 leads from the working chamber (4) to the control membrane (12), and wherein a flow resistance of the control channel (24) is greater than a flow resistance of the throttle channel (10). The invention further relates to a motor vehicle having such a hydraulic mount (2).

Claims

1-15. (canceled)

16. A hydraulic mount comprising: a load-bearing spring; a working chamber at least partially surrounded by the load-bearing spring, wherein the working chamber is filled with a hydraulic fluid; an equalization chamber; a partition arranged between the working chamber and the equalization chamber; a throttle duct formed between the working chamber and the equalization chamber, wherein the throttle duct serves for exchange of hydraulic fluid; a control diaphragm which is designed for the variation of a working chamber volume of the working chamber; and, an actuator for deflection of the control diaphragm; wherein the hydraulic mount comprises a control duct which leads from the working chamber to the control diaphragm, and wherein flow resistance of the control duct is greater than flow resistance of the throttle duct.

17. The hydraulic mount as claimed in claim 16, wherein the flow resistance of the control duct in a vibration frequency range between 5 Hz and 15 Hz is greater than the flow resistance of the throttle duct in a vibration frequency range between 5 Hz and 15 Hz.

18. The hydraulic mount as claimed in claim 16, wherein the flow resistance of the control duct is at least five times the flow resistance of the throttle duct.

19. The hydraulic mount as claimed in claim 16, wherein the throttle duct has a low-pass characteristic with a cutoff frequency f1.

20. The hydraulic mount as claimed in claim 19, wherein the cutoff frequency f1 is between 10 Hz and 30 Hz.

21. The hydraulic mount as claimed in claim 16, wherein the control duct has a low-pass characteristic with a cutoff frequency of f2.

22. The hydraulic mount as claimed in claim 21, wherein the cutoff frequency f2 is between 2 Hz and 7 Hz.

23. The hydraulic mount as claimed in claim 19, wherein the control duct has a low-pass characteristic with a cutoff frequency of f2, and wherein the cutoff frequency f2 is lower than the cutoff frequency f1.

24. The hydraulic mount as claimed in claim 16, wherein a cross section of the control duct is smaller than a cross section of the throttle duct.

25. The hydraulic mount as claimed in claim 24, wherein the cross section of the throttle duct is at least twice the cross section of the control duct.

26. The hydraulic mount as claimed in claim 16, wherein a length of the control duct is greater than a length of the throttle duct.

27. The hydraulic mount as claimed in claim 16, wherein the control duct comprises flow resistance elements which project radially on the inside of the control duct.

28. The hydraulic mount as claimed in claim 16, wherein the control duct comprises flow diverting elements which project radially on the inside of the control duct.

29. The hydraulic mount as claimed in claim 16, wherein the control duct comprises flow resistance elements and flow diverting elements which project radially on the inside of the control duct.

30. The hydraulic mount as claimed in claim 16, wherein an inner wall of the control duct has a roughness of at least 1.4 m.

31. The hydraulic mount as claimed in claim 16, wherein the control duct leads from the partition to the control diaphragm.

32. The hydraulic mount as claimed in claim 16 further comprising a pressure chamber, wherein the control diaphragm is arranged between the control duct and the pressure chamber.

33. The hydraulic mount as claimed in claim 16, wherein the throttle duct and the control duct are formed separately from one another.

34. A hydraulic mount comprising: a load-bearing spring; a working chamber at least partially surrounded by the load-bearing spring, wherein the working chamber is filled with a hydraulic fluid; an equalization chamber; a partition arranged between the working chamber and the equalization chamber; a throttle duct formed between the working chamber and the equalization chamber, wherein the throttle duct serves for exchange of hydraulic fluid; a control diaphragm which is designed for the variation of a working chamber volume of the working chamber; an actuator for deflection of the control diaphragm; and, a control duct which leads from the working chamber to the control diaphragm; wherein the throttle duct has a low-pass characteristic with a cutoff frequency f1, wherein the control duct has a low-pass characteristic with a cutoff frequency of f2, and wherein the cutoff frequency f2 is lower than the cutoff frequency f1.

35. A motor vehicle comprising: a vehicle frame; an engine; and, an engine mount which produces a connection, with mounting action, between the engine and the vehicle frame; wherein the hydraulic mount comprises a load-bearing spring, a working chamber at least partially surrounded by the load-bearing spring, an equalization chamber, a partition arranged between the working chamber and the equalization chamber, a throttle duct formed between the working chamber and the equalization chamber, a control diaphragm which is designed for the variation of a working chamber volume of the working chamber, and an actuator for deflection of the control diaphragm; and, wherein the hydraulic mount comprises a control duct which leads from the working chamber to the control diaphragm, wherein flow resistance of the control duct is greater than flow resistance of the throttle duct, wherein the working chamber is filled with a hydraulic fluid, and wherein the throttle duct serves for exchange of hydraulic fluid;

Description

[0037] The invention will be described below, without restriction of the general concept of the invention, on the basis of exemplary embodiments and with reference to the drawings. In the drawings:

[0038] FIG. 1 shows a schematic cross-sectional view of the hydraulic mount in a first embodiment,

[0039] FIG. 2 shows a schematic view of the hydraulic mount along a section A-A, and

[0040] FIG. 3 shows a schematic cross-sectional view of the hydraulic mount in a second embodiment.

[0041] FIG. 1 shows a hydraulic mount 2. The hydraulic mount 2 comprises a load-bearing spring 36 in the form of a rubber element. Said load-bearing spring 36 is, in the conventional manner, in the form of a hollow body, wherein the top side of the load-bearing spring 36 has a cover 38. A connection element (not illustrated) for the fastening of an engine is normally attached to the cover 38. In a simple embodiment, the connection element is a threaded bolt which can be screwed to the engine. The bottom side of the load-bearing spring 36 is adjoined by the partition 8. The working chamber 4 is formed between the load-bearing spring 36, the cover 38 and the partition 8. The working chamber 4 is filled with a hydraulic fluid. This is preferably a mixture of oil and water. Situated adjacently below the partition 8 in the longitudinal direction L is the hollow cylindrical base housing 40, the interior space of which is divided by a flexible separating body 48. The separating body may for this purpose be produced from elastic material, and/or may be in the form of a rolling diaphragm. The separating body 48 is of ring-shaped form, such that a radially inside edge and a radially outside edge are fastened, spaced apart from one another, to the partition 8. The space enclosed by the partition 8 and the separating body 48 forms the equalization chamber 6 of the hydraulic mount 2. The equalization chamber 6 is preferably likewise filled with hydraulic fluid, which is preferably a mixture of oil and water. It can thus be seen from FIG. 1 that the partition 8 is arranged between the working chamber 4 and the equalization chamber 6.

[0042] For the damping of low-frequency vibrations which are exerted by the engine on the load-bearing spring 36 via the cover 38 and which thus also act on a working chamber volume 14 of the working chamber 4, a throttle duct 10 is provided which is formed between the working chamber 4 and the equalization chamber 6 and which serves for the exchange of hydraulic fluid. As illustrated in FIG. 1, the throttle duct 10 is for example formed by, or enclosed in, the partition 8. If the load-bearing spring 36 is compressed as a result of the vibrations, this normally leads to an increase of the pressure of the hydraulic fluid in the working chamber 4 and/or to a decrease in size of the working chamber volume 14 of the working chamber 4. In both cases, a volume flow of the hydraulic fluid takes place from the working chamber 4 through the throttle duct 10 into the equalization chamber 6. The throttle duct 10 has a diameter adapted such that dissipation occurs, and the vibrations acting on the load-bearing spring 36 are damped. The damping by way of the throttle duct 10 is however effective only for low-frequency vibrations. In the presence of relatively high-frequency vibrations, for example above 20 Hz, virtually no damping or prevention of vibrations whatsoever is effected by way of the throttle duct 10.

[0043] For the isolation of vibrations with a frequency of greater than 20 Hz, the hydraulic mount 2 has a control diaphragm 12 which is fluidically connected to the working chamber 4. For this purpose, a control duct 24 extends from the working chamber 4 to the control diaphragm 12, by way of which control duct the hydraulic connection from the working chamber 4 to the control diaphragm 12 is produced. In other words, the control duct 24 leads from the working chamber 4 to the control diaphragm 12. One end of the control duct 24 is open toward the working chamber 4. For this purpose, the control duct 24 is assigned to the partition 8, wherein at least one section of the control duct 24 may be formed by the partition 8. The remaining section of the control duct 24 may be connected cohesively, in positively locking fashion and/or in non-positively locking fashion to the partition 8. The other end of the control duct 24 is adjoined by the control diaphragm 12. Said control diaphragm closes said end of the control duct 24. Thus, the control diaphragm 12 communicates with the working chamber volume 14 of the working chamber 4.

[0044] The control diaphragm 12 is designed to be displaceable or elastically deformable in the longitudinal direction L. In accordance with its variability of said type, the working chamber volume 14 of the working chamber 4 increases or decreases in size. Said variability of the control diaphragm 12 is utilized advantageously to as far as possible isolate relatively high-frequency vibrations. For this purpose, the control diaphragm 12 is, at its side averted from the control duct 24 or from the working chamber 4, mechanically connected to an armature plunger 46 of an armature 20 of an actuator 16 of the hydraulic mount 2. The actuator 16 furthermore has a stator 18 which is fastened to the base housing 40, with the armature 20 being arranged so as to be mounted movably with respect to said stator. The actuator 16 is an electromagnetic linear actuator. Other actuators are however also conceivable.

[0045] As already discussed, the control diaphragm 12 serves for the isolation of high-frequency vibrations of the hydraulic mount 2 or of an engine with respect to a chassis. The actuator 16 for the actuation of the control diaphragm 12 is thus preferably activated only if such high-frequency vibrations occur. In the presence of low-frequency vibrations and/or in the presence of quasi-steady-state loads of the hydraulic mount 2, there is thus the risk in the case of known hydraulic mounts that the control diaphragm 12, with its hydraulic connection to the working chamber 4, reduces the dynamic stiffness of the hydraulic mount 2 for a low-frequency vibrations and/or quasi-steady-state loads, which can lead to an impairment of the damping of the low-frequency vibrations and/or of the quasi-steady-state loads. It is thus provided, for the hydraulic mount 2 according to the invention, that the flow resistance of the control duct 24 is greater than a flow resistance of the throttle duct 10. If low-frequency vibrations with large amplitudes now occur, relatively large amounts of the hydraulic fluid are conducted from the working chamber 4 through the throttle duct 10 into the equalization chamber 6 and vice versa. Dissipation then occurs in the throttle duct 10, which leads to damping of the low-frequency vibrations. Owing to the relatively high flow resistance of the control duct 24, only a very small amount, or an even negligibly small amount, of the hydraulic fluid passes through the control duct 24 to the control diaphragm 12. Therefore, the vibration characteristics of the hydraulic mount 2 in the presence of low-frequency vibrations are effectively at least substantially not influenced by the control diaphragm 12. It is rather the case that the throttle duct 10, and the two chambers 4, 6 that are fluidically connected by way of the throttle duct 10, dominate the low-frequency vibration characteristics of the hydraulic mount 2. A corresponding situation applies in the case of quasi-steady-state loads. By contrast, if high-frequency vibrations with small amplitudes occur, no exchange of large amounts of hydraulic fluid between the working chamber 4 and the equalization chamber 6 occurs through the throttle duct 10. This can be attributed firstly to said small amplitudes and secondly to the inertia and viscosity of the hydraulic fluid. The throttle duct 10 thus does not contribute to significant damping of the high-frequency vibrations. The high-frequency vibrations can however be at least partially isolated by the control diaphragm 12 owing to its hydraulic connection to the working chamber 4 by way of the control duct 24. There is no need for an exchange of large quantities of hydraulic fluid for this purpose. It is rather possible by way of the control diaphragm 12 for likewise high-frequency vibrations to be generated, which are transmitted by way of the hydraulic fluid in the control duct 12 to the hydraulic fluid in the working chamber 4. With the corresponding introduction of the high-frequency vibrations by way of the control diaphragm 12, the high-frequency vibrations of the hydraulic mount 2 that may arise in the working chamber 4 as a result of external loads on the hydraulic mount 2 are then isolated. With the control diaphragm 12 and the control duct 24, the hydraulic mount 2 is thus designed to isolate high-frequency vibrations of the hydraulic mount 2, which leads to a lowering of the dynamic spring rate of the hydraulic mount 2 in the range of such vibrations.

[0046] To ensure that the control diaphragm 12 has the least possible influence, or even no influence whatsoever, on the damping characteristics of the throttle duct 10 with regard to low-frequency vibrations, it is, as discussed, provided that the flow resistance of the control duct 24 is higher than the flow resistance of the throttle duct 10. This may be realized for example by virtue of the cross section of the throttle duct 10 being larger than the cross section of the control duct 24. The cross section may refer for example to the cross-sectional area of the respective duct. The cross section may alternatively also refer to the cross-sectional diameter of the respective duct. Viewing FIG. 1, it may thus be provided that the cross-sectional diameter d1 of the throttle duct 10 is twice as large as the cross-sectional diameter d2 of the control duct 24. To realize the relatively high flow resistance of the control duct 24, it may alternatively or additionally be provided that the length I1 of the throttle duct 10 is smaller than the length I2 of the control duct 24. The length I2 of the control duct 24 is preferably at least twice the length I1 of the throttle duct 10.

[0047] Referring to FIG. 2, it is pointed out that the throttle duct 10 and/or the control duct 24 may in each case be formed by multiple tubular connections. The respective duct cross section, the respective flow resistance and/or respective other physical characteristics of the throttle duct 10 and/or of the control duct 24 thus represent the corresponding physical characteristics, which are in each case added together and/or superposed, of said tubular connections. As can be seen from FIG. 2, the throttle duct 10 may be formed from four tubular connections, arranged so as to be distributed over the circumference of the partition 8, between the working chamber 4 and the equalization chamber 6, wherein the cross section of the throttle duct 10 is defined by addition of the individual cross sections of the tubular connections. A corresponding situation may apply to the control duct 24.

[0048] FIG. 3 schematically illustrates a further embodiment of the hydraulic mount 2. The hydraulic mount 2 is of substantially identical construction to the hydraulic mount 2 discussed with reference to FIG. 1. Analogous explanations, features and/or advantages thus apply. The hydraulic mount 2 from FIG. 3 however differs substantially with regard to the construction of the control diaphragm 12, of the armature 20 connected to the control diaphragm 12, and of the partition 8.

[0049] As can be seen from FIG. 3, the armature plunger 46 of the armature 20 leads through the partition 8. For this purpose, the armature plunger 46 may be mounted on and/or sealed off against the partition 8. The control diaphragm 12 adjoins that end of the armature plunger 46 which is averted from the stator 18. The control diaphragm 12 is inserted into a pressure chamber housing 22, wherein a pressure chamber 52 is formed between the control diaphragm 12 and the pressure chamber housing 22. The control diaphragm 12 is thus arranged between the control duct 24 and the pressure chamber 52. The pressure chamber housing 22 may be attached to the partition 8, specifically preferably to that side of the partition 8 which faces toward the working chamber 4. Alternatively, the pressure chamber housing 22 may be formed by the partition 8. The pressure chamber 52 may be filled with dried air, gas and/or a gas mixture. With the deflection of the control diaphragm 12, it is thus the case that not only the volume of the working chamber 4 but also the volume of the pressure chamber 52 is varied. Such a construction is basically known from the prior art and is also referred to as an inverted construction.

LIST OF REFERENCE SIGNS

Part of the Description

[0050] d1 Cross-sectional diameter [0051] d2 Cross-sectional diameter [0052] L Longitudinal direction [0053] l1 Length [0054] l2 Length [0055] Q Transverse direction [0056] 2 Hydraulic mount [0057] 4 Working chamber [0058] 6 Equalization chamber [0059] 8 Partition [0060] 10 Throttle duct [0061] 12 Control diaphragm [0062] 14 Working chamber volume [0063] 16 Actuator [0064] 18 Stator [0065] 20 Armature [0066] 22 Pressure chamber housing [0067] 24 Control duct [0068] 36 Load-bearing spring [0069] 38 Cover [0070] 40 Base housing [0071] 46 Plunger [0072] 48 Separating body [0073] 52 Pressure chamber