JPH0628978B2 - Power unit mounting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to a mounting device for mounting a power unit on an automobile body via an elastic mount,
In particular, it relates to a technique for changing the spring constant and damping force of the mount according to the running state of the vehicle.

<< Prior Art >> For example, JP-A-58-161617 and US Pat. No. 270.
No. 5118 discloses a mounting device for a power unit, which uses a mount in which a non-compressible fluid is enclosed and a plurality of mounts are connected by a fluid conduit.

In the former device, the fluid chamber of each mount is divided into an upper chamber and a lower chamber. The upper chamber of one mount and the lower chamber of the other mount are connected by independent conduits. With respect to the bounce vibration of the power unit, a low bounce rigidity is obtained by the moving spring constant when the fluid moves between the upper and lower chambers communicating with each other in both mounts. Further, the roll rigidity is increased because the fluid is not moved between the upper and lower chambers against the roll vibration of the power unit.

In the latter device, each mount has one fluid chamber and the two mount fluid chambers are connected by a conduit having an orifice. When transient large torque fluctuations of the power unit occur, vibration is damped by fluid movement through the orifice.

<< Problems to be Solved by the Invention >> The power unit generates low-frequency large-amplitude vibration (sway) when the vehicle is suddenly accelerated or decelerated. Therefore, it is necessary to sufficiently increase the spring constant and damping force of the mount to suppress this low frequency large amplitude vibration. In this respect, the conventional technique described above is effective.

However, when the vehicle is running smoothly at a substantially constant speed or stopped, if the spring constant and damping force of the mount are set large as described above, high-frequency engine vibration will It is easily transmitted and causes occupant discomfort. In other words, it is preferable that the spring constant and damping force of the mount are small except for the state where low frequency large amplitude vibration is generated, and the vibration transmission to the vehicle becomes small.

As described above, the preferable characteristics of the mounting device differ depending on the running state of the vehicle, but the conventional device has not satisfied such requirements.

The present invention has been made in view of the above-mentioned conventional problems, and changes the mount spring force and the damping force of the mount with good responsiveness according to the operating state of the vehicle, and at the time of sudden acceleration / deceleration, the low frequency of the power unit is used. (EN) Provided is a mounting device for a power unit, which can effectively suppress a large vibration amplitude and can effectively prevent engine vibration from being transmitted to a vehicle body in other states.

<< Means for Solving Problems >> Therefore, in the mounting device of the present invention, a plurality of mounts for elastically supporting the power unit with respect to the vehicle, and a characteristic changing means for changing at least one of the spring constant and the damping force of these mounts are provided. Basically, there is provided switching control means for switching the characteristic changing means to a plurality of modes in accordance with the driving state of the vehicle. Further, the switching control means,
A control means is provided for correcting the mode switching response in accordance with at least one of the spring constant and the damping force before switching (see FIG. 1).

<< Operation >> The spring constant and damping force of the mount are variably controlled by the switching control means to a mode suitable for the operating state of the vehicle.
Particularly, the substantial switching response from the soft mode to the hard mode, which has a large characteristic difference, is higher than that from the normal mode to the hard mode, which has a small characteristic difference, and high-precision control without a control delay is realized.

<< Example >> In FIG. 2, 10 is a vehicle body, 12 is a mount, 14 is a power unit, and 16 is a bracket of the power unit 14. Three or more mounts 12 are provided to elastically connect the bracket 16 of the power unit 14 and the vehicle body 10 and elastically support the power unit 14 to the vehicle body 10.

The mount 12 includes a cylindrical case 18 fixed to the vehicle body 10, a thick rubber elastic wall 20 fixed so as to close an upper end opening of the case 18, and a thin rubber elastic wall closing a lower end opening of the case 18. And a non-compressible fluid (liquid) inside the fluid chamber 24 formed by these three parts.
Is enclosed. The bracket 16 is attached to the upper elastic wall 20, and the load of the power unit 14 is applied to this portion.

Inside the fluid chamber 24, there is an intermediate wall 26 that divides the space into upper and lower parts.
Is attached. The intermediate wall 26 is provided with an orifice 28 that communicates the upper and lower spaces, and a movable plate 30 that is slightly movable in the vertical direction. With this configuration,
The fluid in the fluid wall 24 can flow in the upper and lower spaces with appropriate resistance.

The fluid chambers 24 of the two mounts 12 forming a pair are connected to each other by a conduit 32. Solenoid valve 3 is provided in the middle of this conduit 32.
2 is provided. When the valve 34 is opened, the two fluid chambers 24 communicate with each other to allow the fluid to move, and when the valve 34 is closed, the two fluid chambers 24 become independent. The two mounts 12 forming a pair are arranged on both sides of the crankshaft of the engine.

A pneumatic actuator 36 for restricting the bending displacement of the elastic film 22 is attached to the lower portion of the mount 12. The pneumatic actuator 36 has a built-in diaphragm 38 that is vertically displaced by air pressure as described below, and a pressing plate 40 that interlocks with the diaphragm 38 is attached immediately below the elastic film 22.

It is the negative pressure source 42 (using engine intake pressure) and the solenoid valve 44 that actuate the pneumatic actuator 36. When the solenoid valve 44 is in the illustrated state (non-excited state), the negative pressure source 4
The pressure of 2 acts equally above and below the diaphragm 38.
At this time, the diaphragm 38 is located below by the force of the spring 46, and therefore the holding plate 40 is also located below, and the elastic film 2
2 can be bent and displaced downward.

When the solenoid valve 44 is excited and switched from the illustrated state, the lower chamber of the diaphragm 38 communicates with the atmosphere and the diaphragm 38
The pressure of the negative pressure source 42 acts only on the upper chamber of the. The diaphragm 38 rises due to this pressure difference. At the same time, the holding plate 40 also rises, pushing up the elastic film 22 and holding it against the intermediate wall 26. As a result, the elastic film 22 is constrained and cannot flex freely.

In the apparatus of this embodiment, the solenoid valve 34 is used for the two fluid chambers 24.
By controlling whether the elastic membrane 22 is constrained by the pneumatic actuator 36 and changing the spring constant and the damping force of the mount 12 in the following three states (hard mode). , Soft mode, normal mode)
To produce. This control is performed by the controller 48 including a microcomputer.

-Hard mode The solenoid valve 34 is de-energized and closed, and the fluid chamber 24 of each mount 12 is made independent.

The solenoid valve 44 is de-energized, the pneumatic actuator 36 is not operated, and the elastic film 22 is not restrained.

-Soft mode: The solenoid valve 34 is excited and opened to connect the fluid chambers 24 of the two mounts 12 to each other.

The electromagnetic valve 34 is excited to operate the pneumatic actuator 36 to restrain the elastic film 22.

-Normal mode: The solenoid valve 34 is excited and opened to connect the fluid chambers 24 of the two mounts 12 to each other.

The solenoid valve 44 is de-energized, the pneumatic actuator 36 is not operated, and the elastic film 22 is not restrained.

In the above hard mode, the spring constant and the damping force of the mount 12 become large, and the low frequency large amplitude vibration of the power unit 14 can be effectively controlled.

In the soft mode, the spring constant and the damping force of the mount 12 become small, the vibration of the power unit 14 is well absorbed, and the vibration transmission to the vehicle body 10 becomes small.

The normal mode is an intermediate property between the hard mode and the soft mode, and the roll absolute spring constant is kept constant even if the engine frequency increases.

In this embodiment, the period from the start of the engine due to cranking to a stable idle rotation state until the elapse of a fixed time Ts (for example, 20 seconds) from that time,
As will be described later, the hard mode is set when a sudden acceleration / deceleration operation is performed, the soft mode is set in the idle rotation state or the low speed running state, and the normal mode is set in the running state at a certain speed or more.

In order to perform the switching control of the above three modes, as shown in FIG. 2, an output signal of a rotation sensor 50 for detecting whether the engine is rotating or stopped, and a starter switch for starting the engine. The state signal of 52 and the output signal of the negative pressure sensor 54 that detects the negative pressure of the intake pipe of the engine are input to the controller 48. Based on these input signals, the controller 48 controls according to the procedure shown in the flowchart of FIG.

In FIG. 3, the controller 48 first determines whether or not the engine is stopped (step 100), and if rotation is stopped, sets the characteristics of each mount 12 to the hard mode and sets the stop flag to "1". (Steps 101,10
2). When the starter switch 52 is turned on and cranking is performed to start the engine, the engine starts rotating, and the process proceeds from step 100 to step 200. In step 200, it is determined whether or not the stop flag is "1".
When the rotation start is first detected from the rotation stopped state, the stop flag is "1", and in this case, the process proceeds to the step 201 side.

In step 201, starter switch 52 is turned on.
Wait for the turn off. When the engine starts to rotate due to cranking, the starter switch 52 is turned off. Catch this off timing, step 20
In step 2, a timer for counting the Ts time is started, and in step 203, the time of this timer is awaited. After Ts time has elapsed after the engine is started, the routine proceeds to step 204, where the stop flag is set to "0" and the routine proceeds to step 205.

In step 205, the negative pressure value P of the engine intake pipe at this time
Is sampled from the negative pressure sensor 54. Next steps
In 206, the negative pressure change rate ΔP is calculated from the difference between the latest negative pressure value P and the previously sampled negative pressure value. This ΔP is a detection level of the acceleration / deceleration change described above, and when a sudden acceleration / deceleration operation is performed on the vehicle, first, the intake pipe negative pressure largely changes and the negative pressure change rate ΔP increases. Note that ΔP is an absolute value.

Next, the routine proceeds to step 300, where the negative pressure change rate ΔP is the set value a 1
It is determined whether or not the above. If it has not reached a 1, the routine proceeds to step 301, where the negative pressure value P and the set values P1 and P2 are compared.

The fact that the negative pressure value P is within the range of the set values P1 and P2 means that it is in the idle rotation state or the low speed traveling state. In this case, the process proceeds to step 302 and the characteristics of each mount 12 are set to the soft mode. .

The negative pressure value P being equal to or higher than the set value P2 means that the engine speed is relatively high and the vehicle is in a normal traveling state. Further, the negative pressure value P being less than or equal to the set value P1 means that the engine speed is too low. In both cases, the routine proceeds to step 303, where the characteristics of each mount 12 are set to the normal mode.

After performing step 302 or 303, step 100 → 200
→ 205 → 206 → 300, and again the negative pressure change rate ΔP
And the set value a1.

By performing a sudden acceleration / deceleration operation, the negative pressure change rate ΔP becomes the set value a1.
If so, in step 304, it is determined whether or not the current mode is hard, and if not, it is determined in step 305 whether or not the current mode is soft. If the current mode is soft, proceed to step 305 → 306 to switch to the hard mode.

If the current mode is normal, the process proceeds from step 305 to step 307, and the negative pressure change rate ΔP is compared with the set value a2. The set value a2 is larger than the set value a1. If the negative pressure change rate ΔP is smaller than the set value a2, the process proceeds to step 301 described above, and the soft mode or the normal mode is set according to the negative pressure value P. Negative pressure change rate ΔP is set value a
If it is 2 or more, the process proceeds from step 307 to 306, and the hard mode is set.

When the hard mode is entered after passing through step 306, and when ΔP ≧ a 1 when the next step 300 is executed, step
Proceed from 304 to 308 to determine whether the mode before switching to hardware is soft or normal. If the previous mode was soft, proceed to step 306 to maintain hard mode.

If the previous mode was normal, step 307
Proceed to and compare ΔP with a 2. If ΔP ≧ a2, the process proceeds to step 306 and the hard mode is maintained. Δ
If P <a2, the process proceeds to step 301 to return to the soft mode or normal mode.

In this way, the characteristics of each mount 12 are set to the soft mode or the normal mode depending on the magnitude of the intake pipe negative pressure value P when Ts has elapsed after the engine is started. When the rate of change ΔP of the negative pressure value P becomes larger than the appropriate set value a1 or a2 by performing a sudden acceleration / deceleration operation, step 30
At 6, the characteristics of each mount 12 are switched to the hard mode.

The set value of the negative pressure change rate ΔP that serves as a reference for switching from the soft mode to the hard mode is a1, and the set value of the negative pressure set value ΔP that serves as a reference for switching from the normal mode to the hard mode is a2. a1 is a value smaller than a2.

Setting value a1 when switching from soft mode to hard mode
Is smaller than the set value a2 at the time of switching from the normal mode to the hard mode for the following reason. The characteristic difference is larger when switching from soft mode to hard mode,
If this switching is not realized at a substantially high speed, it is not possible to effectively suppress large fluctuations of the power unit. Since the characteristic difference in switching from the normal mode to the hard mode is not so large, it is not necessary to perform this switching at high speed. Therefore, the set value a for which the negative pressure change rate ΔP is relatively small
When the value exceeds 1, the soft mode is switched to the hard mode so that the actual switching can be performed without delay after the power unit is shaken due to sudden acceleration / deceleration.

In the above embodiment, the acceleration / deceleration change of the vehicle is detected based on the differential value of the negative pressure value of the intake pipe, but the present invention is not limited to this. For example, an acceleration sensor may be provided in the vehicle and the acceleration / deceleration change may be directly detected based on the output of the acceleration sensor. It is also possible to detect acceleration / deceleration changes from accelerator operation and brake operation.

Further, the solenoid valve 34 of the above embodiment is controlled to be fully closed and fully open, but the present invention is not limited to this.
The mount of each mount 1 is controlled by continuously controlling the opening degree of the solenoid valve 34.
The characteristics of 2 may be changed continuously. An example of the characteristic switching control in this case is shown in FIG. 4 corresponds to in FIG.

In the embodiment of FIG. 4, the soft mode and the normal mode are the same as in the previous embodiment. The hard mode is slightly different, and in the hard mode in the previous embodiment, the solenoid valve 34
However, in this embodiment, the opening degree of the solenoid valve 34 in the hard mode is determined according to the negative pressure change rate ΔP.

The correspondence relationship between the negative pressure change rate ΔP and the valve opening degree V (ΔP) of the solenoid valve 34 is stored in the memory of the controller 48 in advance in the form of a map. As this map, as shown in FIG. 5, two types of maps 1 and 2 having different characteristics are prepared. Map 1 is used when the soft mode is switched to the hard mode, and map 2 is used when the normal mode is switched to the hard mode.

Description will be given along the flow of the flowchart of FIG. In step 400, it is determined whether the negative pressure change rate ΔP has become equal to or greater than the set value a. If it has not reached a, the routine proceeds to step 401, where the negative pressure value P and the set values P1 and P2 are compared. P is P1
If it is between P2 and P2, the soft mode is set in step 402. If P is P1 or less or P2 or more, the normal mode is set in step 403.

When the negative pressure change rate ΔP becomes equal to or greater than the set value a by performing a sudden acceleration / deceleration operation, it is determined in step 404 whether the current mode is hard or not, and in step 405 whether the current mode is soft or not is determined. judge. If the current mode is soft, the routine proceeds to step 406, where the valve opening V (ΔP) is determined from the map 1 and set to the hard mode at step 407. The valve opening in this hard mode is V (ΔP).

If the current mode is normal in step 405, the process proceeds to step 408, the valve opening V (ΔP) is determined on the map 2, and the hard mode is set in step 407 according to the valve opening.

When ΔP is a or more and the current mode is hard, it is determined in step 409 whether the previous mode is soft, and if so, the process proceeds to step 406, and if not, the process proceeds to step 408. As is clear from the characteristics, the characteristics of the map 1 have a smaller opening degree of the solenoid valve 34 and become a hard mode with stronger intensity. By adopting this map 1 for switching from the soft mode to the hard mode, and adopting the map 2 having relatively light intensity for switching from the normal mode to the hard mode, the substantial responsiveness at the time of switching of the former is achieved. It will be higher than that.

Further, the specific configuration of the mount 12 and the configuration of the characteristic changing means for changing the spring constant and the damping force of the mount are not limited to the illustrated embodiment, and various implementations are possible.

<Effects of the Invention> As described in detail above, according to the mounting device for a power unit according to the present invention, the mounting of the power unit is extremely responsive in the rapid acceleration / deceleration state of the vehicle in which the low frequency large amplitude vibration is about to occur in the power unit. Changes the characteristics of
The vibration can be effectively suppressed. Further, in other states, the characteristics of the mount automatically change, and it is possible to effectively prevent the engine vibration from being transmitted to the vehicle.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating constituent elements described in claims, FIG. 2 is a block diagram of an apparatus of an embodiment of the present invention, and FIG. 3 is a flowchart of a first embodiment of control operation in the same apparatus. FIG. 4 is a flow chart of the second embodiment of the control operation, and FIG. 5 is a view of the valve opening control characteristic 2 in the second embodiment.
It is a figure which shows two maps. 10 ... Vehicle, 12 ... Mount 14 ... Power unit 22 ... Elastic membrane, 24 ... Fluid chamber 32 ... Conduit, 34 ... Solenoid valve 36 ... Pneumatic actuator 50 ... Rotation sensor 52 ... Starter switch 54 ... Negative pressure sensor

Claims (1)

[Claims] 1. A plurality of mounts for elastically supporting a power unit with respect to a vehicle, a characteristic changing means for changing at least one of a spring constant and a damping force of these mounts, and the characteristic changing means according to a driving state of the vehicle. A switching control means for switching control to a plurality of modes is provided, and the switching control means includes a control means for correcting the switching response of the mode according to at least one of a spring constant and a damping force before switching. The mounting device for the power unit.