Liquid-filled mount

Abstract

To provide a liquid-filled mount that can achieve compatibility between conflicting characteristics required for a mount and that can optimize characteristics of the mount according to an operating state of a powertrain.SOLUTION: A liquid-filled mount 30 includes: an ultrasonic vibrator 40 that is disposed in a main liquid chamber 32 and converts applied high-frequency power into ultrasonic vibration; and an ECU 20 that controls driving of the ultrasonic vibrator 40. When an engine 10 is in a predetermined operating state (for example, an idling operating state in which lower stiffness is required as a characteristic of the mount), the ECU 20 drives the ultrasonic vibrator 40 to generate bubbles in damper oil (silicone oil) 37.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fluid-filled mount. [Background technology]

[0002] Conventionally, hydraulic mounts have been widely used to absorb and suppress vibrations transmitted from the powertrain, such as the engine and transmission, to the vehicle body (see, for example, Patent Document 1). For example, an engine or the like is supported on the vehicle body by multiple (three or four) hydraulic mounts. Each hydraulic mount is disposed between the engine or the like and the vehicle body, and absorbs and suppresses vibrations transmitted from the engine or the like to the vehicle body.

[0003] A liquid-filled mount has, for example, a primary liquid chamber (pressure-receiving chamber) to which vibrations are input via a rubber elastic body, and an auxiliary liquid chamber (balance chamber) that is connected to the primary liquid chamber via an orifice, with liquid sealed in the primary liquid chamber and the auxiliary liquid chamber. In a liquid-filled mount, vibrations from an engine or the like are absorbed and damped by liquid flowing between the primary liquid chamber and the auxiliary liquid chamber via the orifice. A liquid-filled mount is configured to exhibit high damping characteristics in the resonant frequency range (around 5 to 20 Hz) of the engine support system, for example. The frequency of vibrations absorbed and damped by the flow of liquid in the orifice is tuned by the cross-sectional area and length of the orifice. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-337348 Summary of the Invention [Problem to be solved by the invention]

[0005] The optimal characteristics (damping characteristics, rigidity, etc.) required of a fluid-filled mount vary depending on the operating state of the powertrain, such as the engine, to which it is mounted. More specifically, a fluid-filled mount is required to have high rigidity to reduce engine shake caused by, for example, starting, sudden acceleration, or sudden deceleration, and low rigidity to reduce engine vibration (especially idling vibration, etc.). In other words, a fluid-filled mount is required to have the contradictory characteristics of high rigidity and low rigidity in addition to the high damping described above.

[0006] The present invention has been made to solve the above problems, and aims to provide a hydraulic mount that can achieve the conflicting characteristics required of a mount and can optimize the mount's characteristics according to the operating state of the powertrain. [Means for solving the problem]

[0007] A liquid-filled mount according to one aspect of the present invention is a liquid-filled mount comprising: a mount case formed in an approximately cylindrical shape, inside which a main liquid chamber and an auxiliary liquid chamber communicating with the main liquid chamber via an orifice are formed along the axial direction; an elastic member provided on the end face of the mount case facing the main liquid chamber, which seals the main liquid chamber and the auxiliary liquid chamber liquid-tightly and to which the powertrain is attached; and damper oil sealed in the main liquid chamber and the auxiliary liquid chamber.The liquid-filled mount further comprises: an ultrasonic vibrator disposed in the main liquid chamber and vibrating in response to an applied electrical signal; and a control unit which controls the driving of the ultrasonic vibrator, wherein the control unit drives the ultrasonic vibrator to generate bubbles in the damper oil when the powertrain is in a predetermined operating state.

[0008] According to one aspect of the present invention, when the powertrain is in a predetermined operating state, an ultrasonic vibrator is activated to generate bubbles in the damper oil. Here, the bulk modulus of the bubbles (gas) is smaller than that of the damper oil (liquid). Therefore, as the amount of bubbles increases, the stiffness of the damper oil decreases. Therefore, by activating the ultrasonic vibrator to generate compressible bubbles in the damper oil, a mount with lower stiffness can be obtained. On the other hand, by stopping the activation of the ultrasonic vibrator and eliminating the bubbles, the mount can be restored to a higher stiffness (its original stiffness). Therefore, the stiffness of the hydrostatic mount (high stiffness and low stiffness) can be switched depending on the operating state of the powertrain, achieving both of these opposing characteristics. [Effects of the Invention]

[0009] According to the present invention, it is possible to achieve both of the contradictory characteristics required of a mount, and to optimize the mount characteristics according to the operating state of the powertrain. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing the configuration of a fluid-filled mount according to an embodiment. [Figure 2] 1 is a diagram showing the configuration of an engine to which a hydraulic mount according to an embodiment is applied; [Figure 3] 10 is a flowchart showing the procedure of a process for switching characteristics (rigidity) of a fluid-filled mount according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] A preferred embodiment of the present invention will be described in detail below with reference to the drawings. Note that, unless otherwise necessary, the same or equivalent parts in the drawings will be designated by the same reference numerals. Furthermore, the same elements in each drawing will be designated by the same reference numerals, and redundant explanations will be omitted. In this embodiment, a hydraulic engine mount will be used as an example of a hydraulic mount.

[0012] First, the configuration of a hydraulic mount 30 according to an embodiment will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view showing the configuration of the hydraulic mount 30. Figure 2 is a diagram showing the configuration of an engine 10 to which the hydraulic mount 30 is applied.

[0013] First, referring to Figure 2, an engine 10 to which a hydraulic mount 30 is applied will be described. The engine 10 may be of any type, for example, a horizontally opposed four-cylinder gasoline engine. The engine 10 is a direct injection engine that injects fuel directly into the cylinders. In the engine 10, air is drawn in through an air cleaner, throttled by a throttle valve provided in an intake pipe, passes through an intake manifold 11, and is drawn into each cylinder formed in the engine 10.

[0014] An injector 12 that injects fuel into the cylinder is attached to each cylinder of the engine 10. The injector 12 injects fuel pressurized by a high-pressure fuel pump directly into the combustion chamber of each cylinder.

[0015] The cylinder head of each cylinder is also fitted with a spark plug 13 that ignites the air-fuel mixture, and an igniter-integrated coil 14 that applies high voltage to the spark plug 13. In each cylinder of the engine 10, the air-fuel mixture of intake air and fuel injected by the injector 12 is ignited by the spark plug 13 and combusted. Exhaust gas after combustion is discharged through an exhaust pipe 15.

[0016] A cam angle sensor 16 for identifying the cylinders of engine 10 is attached near the camshaft of engine 10. A crank angle sensor 17 for detecting the rotational position of crankshaft 10a is attached near the crankshaft 10a of engine 10. A timing rotor 17a having, for example, 34 protrusions with two teeth missing, formed at 10° intervals, is attached to the end of crankshaft 10a. Crank angle sensor 17 detects the presence or absence of the protrusions on timing rotor 17a to detect the rotational position of crankshaft 10a.

[0017] These sensors are connected to the ECU 20. Also connected to the ECU 20 are an accelerator sensor 22 that detects the amount of depression (operation amount) of the accelerator pedal, a water temperature sensor 23 that detects the temperature of the cooling water (water temperature), and the like. The ECU 20 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute various processes, a RAM that stores various data such as calculation results, a backup RAM in which the stored contents are maintained by a battery, an input / output I / F, and the like. The ECU 20 also includes an injector driver that drives the injector 12, an output circuit that outputs an ignition signal, and the like.

[0018] The ECU 20 identifies the cylinder from the output of the cam angle sensor 16, and determines the engine rotation speed from the output of the crank angle sensor 17. The ECU 20 also acquires various information such as the intake air amount, intake manifold pressure, accelerator operation amount, air-fuel ratio of the mixture, and water temperature and oil temperature of the engine 10 based on detection signals input from various sensors. The ECU 20 then comprehensively controls the engine 10 by controlling the fuel injection amount, ignition timing, and various devices based on the acquired information.

[0019] The engine 10 is supported on the vehicle body (frame) 50 by multiple (three or four) hydraulic mounts 30. Each hydraulic mount 30 is interposed (disposed) between the engine 10 and the vehicle body 50, and absorbs and suppresses vibrations transmitted from the engine 10 to the vehicle body 50. Next, the configuration of the hydraulic mount 30 will be described with reference to FIG. 1.

[0020] The mount case (casing) 31 of the fluid-filled mount 30 is made of, for example, iron and is formed in a generally cylindrical shape. Inside the mount case 31, there are formed a primary liquid chamber (pressure-receiving chamber) 32 and an auxiliary liquid chamber (equilibrium chamber) 33 that communicates with the primary liquid chamber 32 via an orifice 34. The primary liquid chamber 32 and the auxiliary liquid chamber 33 are arranged along the axial direction of the mount case 31.

[0021] An elastic member 35 is attached to the end face (top face) of the mount case 31 on the side of the main fluid chamber 32. The elastic member 35 is made of, for example, rubber and is formed in a cylindrical or truncated cone shape. The engine 10 is fastened (mounted) to the elastic member 35 with bolts 38.

[0022] On the other hand, for example, a disk-shaped diaphragm 36 is attached to the end face (bottom face) of the mount case 31 on the auxiliary liquid chamber 33 side. The elastic member 35 and the diaphragm 36 liquid-tightly seal the inside of the mount case 31 (the main liquid chamber 32 and the auxiliary liquid chamber 33).

[0023] Damper oil (liquid) 37 is sealed in the primary liquid chamber 32 and the secondary liquid chamber 33. For example, silicone oil or the like is suitably used as the damper oil 37. For example, a gas containing nitrogen as a main component (nitrogen, air, etc.) is dissolved in the damper oil 37. Note that, from the viewpoint of preventing deterioration (oxidation) of the silicone oil, it is preferable that the gas does not contain oxygen.

[0024] In particular, the hydraulic mount 30 can achieve the contradictory characteristics (high rigidity and low rigidity) required of a mount, and has the function of optimizing the mount characteristics according to the operating state of the engine 10.

[0025] For this purpose, the fluid-filled mount 30 includes an ultrasonic transducer 40 that converts the applied high-frequency power into ultrasonic vibrations (i.e., vibrates in response to the applied electrical signal). The ultrasonic transducer 40 is mounted, for example, inside the primary liquid chamber 32.

[0026] The ultrasonic vibrator 40 includes, for example, an electrostrictive element that generates displacement (distortion) when a voltage is applied. A suitable electrostrictive element is, for example, lead zirconate titanate (PZT), which vibrates when an AC voltage is applied. The shape, size, mounting location, mounting method, vibration frequency, and other factors of the ultrasonic vibrator 40 are set (tuned) according to requirements. However, the vibration frequency must be a frequency that can cause cavitation depending on the type of damper oil (silicone oil) 37 and the gas dissolved therein. Instead of an electrostrictive element, a magnetostrictive element that generates displacement (distortion) when a magnetic field (magnetic field) is applied can also be used.

[0027] The drive of the ultrasonic vibrator 40 is controlled by the ECU 20 (corresponding to a control unit in the claims). Here, a high-frequency power generating unit 41 shown in Fig. 2 oscillates, for example, a high-frequency signal and uses the high-frequency signal to switch power supplied from a battery 42 to generate high-frequency power, which is supplied (applied) to the ultrasonic vibrator 40. The ECU 20 controls the generation and supply (application) of high-frequency power by the high-frequency power generating unit 41, thereby controlling (turning on / off) the drive of the ultrasonic vibrator 40.

[0028] When the engine 10 is in a predetermined operating state, the ECU 20 activates the ultrasonic vibrator 40, generating bubbles (bubbles primarily composed of nitrogen) in the damper oil (silicone oil) 37. Because the bulk modulus of the bubbles (gas) is smaller than that of the damper oil 37 (liquid), the stiffness of the damper oil 37 decreases as the amount of bubbles increases. Therefore, when the ultrasonic vibrator 40 is activated (turned on), compressible bubbles are generated in the damper oil 37, causing the characteristics of the liquid-filled mount 30 to have lower stiffness (the characteristics of the original elastic member 35). When the ultrasonic vibrator 40 is deactivated (turned off), the bubbles disappear, restoring the mount 30 to a higher stiffness (its original characteristics). The bubbles disappear (dissolve) within, for example, several seconds.

[0029] That is, when the engine 10 is operating in a state requiring a lower mount stiffness, the ECU 20 drives the ultrasonic vibrator 40. On the other hand, when the engine 10 is operating in a state requiring a higher mount stiffness, the ECU 20 stops driving the ultrasonic vibrator 40. This allows the stiffness (high stiffness and low stiffness) of the hydronic mount 30 to be switched depending on the engine 10 operating state.

[0030] More specifically, the ECU 20 drives the ultrasonic vibrator 40 when the engine 10 is idling, that is, when the accelerator pedal is released and the engine speed is substantially stable at or below a predetermined speed (e.g., 700 to 800 rpm). The generation of air bubbles in the damper oil 37 reduces the rigidity of the hydrodynamic mount 30, thereby reducing idling vibration. Meanwhile, the ECU 20 stops driving the ultrasonic vibrator 40 when the engine 10 is in an operating state other than idling. The disappearance (dissolution) of the air bubbles increases the rigidity of the hydrodynamic mount 30 (returning it to its original rigidity), thereby reducing engine shake.

[0031] Next, the operation of the hydraulic mount 30 will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the procedure for characteristic (rigidity) switching processing for the hydraulic mount 30. This processing is repeatedly executed by the ECU 20 at predetermined timings.

[0032] First, in step S100, it is determined whether or not the engine 10 is idling. If the engine 10 is not idling, the process proceeds to step S102. On the other hand, if the engine 10 is idling, the process proceeds to step S104.

[0033] In step S102, the driving of the ultrasonic vibrator 40 is stopped. Then, the air bubbles in the damper oil 37 disappear (dissolve), and the rigidity of the hydrophilic mount 30 is restored (made even more rigid). After that, the process temporarily exits.

[0034] In step S104, the ultrasonic vibrator 40 is driven. Then, bubbles are generated in the damper oil 37, which reduces the rigidity of the hydronic mount 30 and reduces idling vibration. After that, the process temporarily exits.

[0035] As described above in detail, according to this embodiment, when the engine 10 is in a predetermined operating state, the ultrasonic vibrator 40 is driven to generate compressible bubbles in the damper oil 37. This allows for a lower rigidity mount characteristic. On the other hand, by stopping the driving of the ultrasonic vibrator 40 and eliminating (dissolving) the bubbles, the higher rigidity mount characteristic (original characteristic) can be restored. Therefore, the rigidity (high rigidity and low rigidity) of the hydrostatic mount 30 can be switched depending on the operating state of the powertrain, making it possible to achieve both of these contradictory characteristics.

[0036] As a result, it is possible to achieve both of the contradictory characteristics (high rigidity and low rigidity) required of the mount, and it is possible to optimize the characteristics of the mount according to the operating state of the engine 10.

[0037] Furthermore, according to this embodiment, when the engine 10 is operating in a state that requires a lower mount stiffness, the ultrasonic vibrator 40 is driven, and when the engine 10 is operating in a state that requires a higher mount stiffness, the driving of the ultrasonic vibrator 40 is stopped. Therefore, the stiffness (high stiffness and low stiffness) of the hydrostatic mount 30 can be switched depending on the engine 10 operating state (depending on the requirement).

[0038] More specifically, according to this embodiment, the ultrasonic vibrator 40 is driven when the engine 10 is idling, and is stopped from being driven when the engine 10 is in an operating state other than idling. Therefore, by setting the rigidity low during idling, it is possible to absorb and suppress the transmission of idling vibration. On the other hand, by setting the rigidity high during times other than idling, it is possible to absorb and suppress the transmission of engine shake.

[0039] According to this embodiment, the ultrasonic vibrator 40 includes an electrostrictive element that converts applied high frequency power into ultrasonic vibrations (i.e., vibrates in response to applied electrical signals). Therefore, the ultrasonic vibrator 40 can be electrically controlled and can appropriately generate ultrasonic vibrations.

[0040] According to this embodiment, the damper oil 37 is silicone oil, and the main component of the bubbles is nitrogen, so that oxidation (deterioration) of the silicone oil can be suppressed.

[0041] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiments, an engine mount that supports the engine 10 has been described as an example, but the present invention can also be applied to a mount that supports a transmission, for example. In that case, the drive (control) of the ultrasonic vibrator 40 can be controlled by a TCU that controls the transmission, instead of the ECU 20 that controls the engine 10.

[0042] Furthermore, the material, shape, size, mounting location, mounting method, vibration frequency, etc. of the ultrasonic vibrator 40 are not limited to those in the above embodiment, but can be arbitrarily set (tuned) according to requirements, etc. Furthermore, for example, the outer shape of the mount case 31 can be any shape and is not limited to those in the above embodiment.

[0043] In the above embodiment, silicone oil is used as the damper oil 37, but other liquids may be used instead of silicone oil. Also, in the above embodiment, nitrogen or air is used as the gas, but other gases may be used instead of nitrogen or air. [Explanation of symbols]

[0044] 10 Engine 17 Crank angle sensor 20 ECU (control unit) 22 Accelerator sensor 23 Water temperature sensor 30 Liquid Mount 31 Mounting case 32 Main liquid chamber 33 Secondary liquid chamber 34 Orifice 35 Elastic member 36 Diaphragm 37 Damper oil (liquid) 38 volts 40 Ultrasonic transducer 41 High frequency power generation unit 42 Battery 50 Body (frame)

Claims

1. a mount case formed in a substantially cylindrical shape, and having a main liquid chamber and an auxiliary liquid chamber communicating with the main liquid chamber via an orifice formed therein along an axial direction; an elastic member provided on an end surface of the mount case on the side of the main liquid chamber, for liquid-tightly sealing the main liquid chamber and the auxiliary liquid chamber, and for mounting a power train; a damper oil sealed in the primary liquid chamber and the secondary liquid chamber, an ultrasonic vibrator disposed in the main liquid chamber and vibrating in response to an applied electrical signal; a control unit for controlling the driving of the ultrasonic transducer; The control unit is configured to drive the ultrasonic vibrator to generate bubbles in the damper oil when the powertrain is in a predetermined operating state.

2. The control unit driving the ultrasonic vibrator when the powertrain is in an operating state that requires a mount with lower rigidity; When the driving state of the powertrain is in a state where higher rigidity is required as a mount characteristic, driving of the ultrasonic vibrator is stopped.

2. The fluid-filled mount of claim 1.

3. the powertrain is an engine, The control unit driving the ultrasonic vibrator when the engine is in an idling state; When the engine is in an operating state other than an idling state, driving of the ultrasonic vibrator is stopped.

3. The fluid-filled mount of claim 2.

4. the damper oil is silicone oil, 4. The liquid-filled mount according to claim 3, wherein the main component of the bubbles is nitrogen.

5. 5. The fluid-filled mount according to claim 4, wherein the ultrasonic vibrator includes an electrostrictive element or a magnetostrictive element.

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