JPH0628979B2 - Power unit mounting device - Google Patents

Description

The present invention relates to a mounting device for a power unit.

(Prior Art) Recently, from the viewpoint of reducing fuel consumption and improving habitability in the passenger compartment, many automobiles (though generally small cars) are FR.
With the shift from the (front engine rear drive) system to the FF (front engine front drive) system, the weight of the vehicle centering on the vehicle body has been reduced.

On the other hand, in order to respond to the sophistication and diversification of the user demand level for automobiles, the tendency toward higher output of the engine itself at the same time as the above-mentioned tendency toward weight reduction of the vehicle body, such as mounting of a high-performance engine and a 4WD (4-wheel drive) power unit It is in. On the other hand, the improvement of the comfortability in the vehicle compartment also requires low vibration and quietness in the vehicle compartment.

However, the weight reduction of the vehicle body itself and the mounting of the high-power engine as described above are in a completely contradictory relationship from the viewpoint of low vibration and quietness in the vehicle interior. In particular, the engine portion is the largest source of vibrations for vehicle interior vibration and noise, and in order to satisfy both of the above requirements and to achieve low vibration and noise in the vehicle interior, The entire drive section including the above, that is, the mount structure itself for the vehicle body of the power unit must have an effective function corresponding to the above requirements.

Of course, the power unit generally has a mounting structure that absorbs vibration to some extent by mounting the power unit on the vehicle body through a rubber member having a predetermined elastic coefficient.

However, this mounting structure has the following drawbacks.

That is, the rubber member at each support point as described above cannot always sufficiently cope with the torque fluctuation that changes depending on the operating state because it has only a constant elastic coefficient (spring constant and damping constant). In particular, a large elastic displacement state is exhibited due to a transient drive torque fluctuation, and the power unit supported by them is largely displaced. Especially, when the transient drive torque is applied during acceleration or deceleration, it acts in the longitudinal direction of the vehicle body. It is easy to cause an extremely low frequency (~ 10 Hz) swaying vibration (surge vibration) or a low frequency (~ 30 Hz) shock vibration that acts on the vertical and front and rear of the vehicle body. Further, the effect of reducing general high-frequency vibration (engine speed secondary component) itself generated by steady engine rotation is not always sufficient.

The above-mentioned hiccup vibration and shock vibration are the lowest order vibrations excited in the drive system and the torsion system when a transient drive torque acts on the engine, especially during acceleration / deceleration of the vehicle,
This causes vibration in the front-rear direction of the vehicle body through the tires and suspension, and at the same time, the power unit receives the reaction force, and shocking input from the engine mount acts on the vehicle body to cause vibrations in the up-down and front-rear direction of the vehicle body. Form. Therefore, the hiccup vibration is generated mainly due to the torque fluctuation of the drive system and the torsion system, while the shock vibration is a combination of the vibration of the power unit and the vehicle body system.

Therefore, in order to eliminate the drawbacks caused by the rubber mount, the power unit has two upper and lower chambers, which are arranged on both the left and right sides of the rotation axis of the power unit and in which incompressible fluid is sealed, and the partition walls of the upper and lower chambers have the above-mentioned two chambers. It has a pair of left and right mounts to which the legs of the power unit are connected, and the lower chamber of the left mount and the upper chamber of the right mount are bounced by the fluid between the upper and lower chambers communicating with each other against bounce vibration. While low bounce rigidity is obtained by the moving spring constant when moving, the roll rigidity is increased by preventing fluid movement between the upper and lower chambers against the roll vibration of the power unit. It is possible to prevent large displacement of the power unit (low frequency vibration) during rolling and reduce general engine vibration (high frequency vibration). There has been proposed a mounting device for a power unit (see, for example, Japanese Patent Laid-Open No. Sho 5).
8-16161).

However, in this conventional technique, it is possible to surely absorb the vertical vibration at the time of bounce and the rolling vibration due to the displacement of the power unit at the time of rolling, respectively, but on the other hand, the purpose is essentially to increase the roll rigidity. Moreover, due to the high roll rigidity, the transmissibility of the fluctuation torque of the power unit due to the engine rotation during acceleration or deceleration to the base becomes large, and it is difficult to mitigate the vibrations and noises resulting from them.

On the other hand, as another conventional example other than the above, as disclosed in, for example, U.S. Pat. No. 2,705,118 and the drawings, a pair of mounts disposed on both sides of the rotary shaft of the power unit are provided as The power unit is configured to have one fluid chamber in which a compressive fluid is sealed, and the fluid chambers of both mounts are connected to each other by a conduit having an orifice so that a transient torque fluctuation is attenuated by the orifice. What you have done is already known.

By the way, the inventors of the present invention relate to this prior art, for the purpose of reducing the roll rigidity of the mounting device, that is, the basic configuration thereof, that is, the fluid chambers of the mounts arranged on both sides of the rotating shaft of the power unit. Various studies were repeated on the configuration in which the pipes are communicated with each other. Due to the resonance phenomenon of the fluid in the pipes, the roll rigidity of the mounting device is 6th in accordance with the change in the frequency due to the torque fluctuation of the power unit. It was found that it changes as shown in the figure. That is, the spring constant representing the roll rigidity described above is (1) almost equal to the static spring constant K at the time of fluid chamber communication because the fluid moves in the conduit in the low frequency range, and decreases as the frequency increases. And reaches the minimum value at the frequency fa.

(2) When the frequency further exceeds the minimum value frequency fa and increases due to the inertial force of the fluid in the conduit that is proportional to the square of the acceleration value, it becomes difficult for the fluid to flow in the conduit. However, at the frequency fe, it becomes equal to the non-communication spring constant (1 + N) K (N is the expansion / movement spring constant ratio of the elastic wall in the mount) when the fluid chamber is not in communication.

(3) It further increases beyond the above frequency fe and reaches the maximum value at the number frequency fn of the fluid in the conduit.

(4) In a frequency range higher than the natural frequency fn, the frequency decreases with an increase in the frequency and gradually approaches the non-communication spring constant (1 + N) K in a state where the fluid does not flow in the conduit.

Considering the above results, the roll rigidity can be reduced when the roll frequency of the power unit is in the low frequency range in the configuration of the above-described conventional technology, but in the high frequency range, the roll rigidity becomes as high as that in the non-communication period, and therefore, always Means that the roll rigidity cannot be kept low.

Therefore, in order to solve this drawback, the present inventors have arranged a pair of mounts in which incompressible fluid is sealed for elastically supporting the power unit on the base on both sides of the rotary shaft of the power unit. At the same time, a conduit for communicating the fluid chambers of the both mounts with each other to allow the movement of the fluid and associating the pressure change of both fluid chambers is provided, and further, a part of the wall of each fluid chamber is provided according to the change of the fluid chamber pressure. The elastic membrane deformation restraint means for selectively preventing deformation of the elastic membrane, and the elastic membrane deformation restraint by introducing negative pressure from a negative pressure source or opening to the atmosphere. A mounting device for a power unit provided with an actuator for activating the means has been previously proposed (Japanese Patent Application No. 60-6).
8306).

According to the configuration of the present invention, during roll vibration of the power unit, in the high frequency region where the fluid does not move in the conduit due to the increase in frequency, negative pressure is introduced into the negative pressure chamber of the actuator to restrain the elastic membrane deformation. When the function of the means is stopped and deformation of the elastic film is allowed, the volume change of the fluid chamber of each mount is absorbed by the deformation of the elastic film, and low roll rigidity can be maintained.

In the low frequency range, the negative pressure chamber of the actuator is opened to the atmosphere to prevent the elastic membrane from being deformed by the elastic membrane deformation restraint means. It can be absorbed by moving the roll, and the roll rigidity can be kept low by utilizing the communication effect area where the roll spring constant is minimized, so that the spring characteristic at the time of rolling can be always softened. .

Further, the elastic film deformation restraint means utilizes the negative pressure of the negative pressure source such as the negative pressure of the intake air in the engine intake pipe to introduce the negative pressure into the negative pressure chamber of the actuator or to the atmosphere in the negative pressure chamber. Since it operates by opening, the elastic film deformation restraint means can be reliably operated with large power by using the negative pressure as a pressure source.

(Problems to be solved by the invention) However, if a low roll rigidity is always obtained regardless of the operating state of the engine as described above, a large torque transiently occurs due to a change in the gear ratio, particularly during gear shifting. It will be rather negative in the case of fluctuations, and will cause large displacements.

Therefore, it is necessary to detect the above-described gear shift state in which the torque fluctuation is particularly large by some means, and increase the rigidity (mount characteristic) (hard) in the detected state.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above problems, and a mounting characteristic of a power unit configured by an engine and a transmission mechanism specified by a spring constant or a damping constant. In a mounting device of a power unit mounted on a vehicle body through a variable mount means, a rotation speed detection means for detecting an input rotation speed input from the engine to the speed change mechanism, and a detection value of the rotation speed detection means And a mount characteristic control means for controlling the mount characteristic of the mount means to the hardware side within a predetermined period when a change in the input rotational speed equal to or greater than a predetermined set value is detected.

(Operation) According to the above means, when a transient and large torque fluctuation occurs during gear shifting, the mounting characteristics specified by the spring constant or damping constant are hard (high rigidity) based on the input rotation speed to the transmission. ) Side, the displacement and vibration of the power unit during the torque fluctuation can be effectively prevented with particularly high responsiveness.

(Embodiment) FIGS. 2 to 4 show a mounting device for a power unit according to a first embodiment of the present invention.

First, FIG. 2 shows the system configuration of the entire apparatus of the above-mentioned embodiment. In FIG. 2, reference numeral 1 denotes a vehicle body frame to which the power unit 2 is mounted, for example, in the vehicle front engine room. The power unit 2 includes, for example, a horizontal engine body 4 and a transmission 5 (see FIG. 3) integrally connected to the output shaft side of the engine body 4.
The transmission 5 side of is a rubber mount member
(Not shown), the engine body 4 side is supported by a pair of mounting brackets 3A, 3B extending from the lower position to the left and right sides, and the spring constant or damping constant described below. Is mounted on the vehicle body frame 1 via a pair of mount characteristic variable type mount members (corresponding to mount means in claims) 7A, 7B.

The mounting members 7A and 7B are respectively fixed to the vehicle body frame 1 and have a cylindrical housing 8 whose upper and lower ends are open, and an upper end side opening of the housing 8 is hermetically sealed and attached to the mounting brackets 3A and 3B. Sleeve-shaped fastening bolt 9
Rubber wall 1 with predetermined elasticity joined through A and 9B
0A, 10B, elastic films 11A, 11B having a rigidity lower than that of the rubber walls 10A, 10B for sealing the lower end side opening of the housing 8, the rubber walls 10A, 10B and the elastic film 11A, Movable plate 1 for partitioning the enclosed space in the housing 8 formed by 11B into upper and lower chambers
2A, 12B, and the upper chamber side of the internal space of the housing 8 defined by the movable plates 12A, 12B is provided with a conduit 1 in which a rotary valve 13 is interposed therebetween.
4 and the lower chamber side defined by the movable plates 12A and 12B, the stopper portions 15A and 15B holding the movable plates 12A and 12B so as to be movable up and down on the peripheral side thereof. The damper orifices 16A and 16B are formed so as to communicate with each other.

An incompressible fluid 20 is enclosed in each of the lower chamber and the upper chamber and the conduit 14.

On the other hand, the rotary valve 13 is driven by an electromagnetic solenoid to control the communication state between the pair of mount members 7A and 7B according to the engine operating state.
(Open and close). This control signal is supplied from the control unit 21, which will be described in detail later.

Further, reference numerals 30A and 30B denote the mount members 7A,
7B shows negative pressure actuators respectively attached to the lower part of 7B, and these negative pressure actuators 30A and 30B are the negative pressure chambers 32A and 3B in the body cases 31A and 31B.
2B is divided into upper and lower chambers by diaphragms 33A and 33B, and the upper chamber side and the lower chamber side are communicated with each other 3
The diaphragm members 33A and 33B are supported by rod-shaped plunger members 37A and 37B, respectively.
The upper ends of 7A and 37B project above the upper surfaces of the body cases 31A and 31B to face the elastic films 11A and 11B of the mount members 7A and 7B, and the elastic films 11A and 11B are located at the protruding ends. There are provided circular position regulating plates 39A and 39B that can come into contact with. A coil spring 40 is provided between the upper surfaces of the body cases 31A and 31B and the plunger members 37A and 37B.
A and 40B are compressed and the coil springs 40A and 4A
0B constantly urges the plunger members 37A, 37B in the descending direction (the direction in which the position regulating plates 39A, 39B are separated from the elastic films 11A, 11B). Then, when the plunger members 37A, 37B are positioned at the lowermost ends, the distance between the position regulating plates 39A, 39B and the elastic films 11A, 11B is set to the stopper plates 15A, 15B and the elastic film 11 respectively.
The distance between the elastic membranes 11A and 11B becomes equal to
While allowing the deformation of 11B, on the other hand, when the plunger members 37A, 37B are raised against the biasing force of the coil springs 40A, 40B, the position regulating plate 39
A and 39B press the elastic film 7 against the stopper plates 15A and 15B to act to prevent the deformation.

The first communication passage 35 is provided with a negative pressure source via a negative pressure pipe 41, a check valve 42 and an accumulator 43.
It is connected to the (negative pressure pump) 45. Further, the second communication passage 36 is selectively communicated with the negative pressure pipe 41 or the atmosphere introducing portion 43 via an electromagnetic switching valve 46. The operating state of the electromagnetic switching valve 46 is controlled by the control unit 21 described later.

On the other hand, as shown in FIG. 3, the input shaft 50 of the transmission 5 is provided with a rotation speed sensor 51 for detecting the rotation speed thereof, and the detection value of the rotation speed sensor 51 is stored in the control unit 21. It is supposed to be entered.

The control unit 21 includes, for example, a microprocessor (CPU) as a center and a memory (ROM and RAM).
And an interface circuit.

Then, the control unit 21 compares the change rate a of the detected value of the rotation speed sensor 51 attached to the input shaft 50 of the transmission 5 with a predetermined set value a ₁ so that the change rate is equal to or more than a certain value. The negative pressure actuators 30A, 30B are provided with a change rate comparison circuit (not shown) for detecting the presence of the negative pressure actuator.
In addition, the rotary valve 13 is controlled as shown in FIG. The specific control contents will be described in detail below.

Next, the control operation of the negative pressure actuators 30A and 30B and the rotary valve 13 by the control unit 21 will be described in detail with reference to the flowchart of FIG.

First, after starting the control operation accompanied by turning on the starter switch (ignition switch) SW, it is determined in step S ₁ whether or not the engine speed is 0 (engine stopped state), and if YES, to step S ₂ . willing negative pressure actuator 30A above, 30B and inoperative, the timer set corresponding to the cranking time in step S ₃ after holding each rotary valve 13 in the closed state (t
₁ second) and the state is indicated as FLAG1 and the process proceeds to step S ₄ . If NO in step S ₁ above,
The process proceeds to step S ₄ as it is. When the negative pressure actuators 30A and 30B are not in operation, the electromagnetic switching valve 46 is switched to the negative pressure pump 45 side by a control signal from the control unit 21, and the negative pressure actuators 30A and 30B are operated.
The lower chamber side is communicated with the negative pressure pump 45. Therefore, in this state, the position regulating plates 39A, 39B of the negative pressure actuators 30A, 30B are
Is positioned at the lowermost end by the urging force of the coil springs 40A and 40B, the elastic films 11A and 11B are freed, and the closed state of the rotary valve 13 prevents the fluid movement between the mount members 7A and 7B. The mounting characteristics become hard (Fig. 6 cranking area).

Next, in step S _4, the current operating condition is determined whether the FLAG1, YES, i.e., if a cranking corresponding state yet, OFF from ON of the starter switch SW further proceeds to step S ₅ transition to, i.e. to check the start of the engine, further course of the cranking time t ₁ at step S _6, i.e. the flow proceeds to the next step S ₇ in terms of determining the start completion of the engine, the timer set FLAG to zero Reset it. Determination in step S _5, S ₆ is the determination result each is repeated until is YES.

When the operation of step S ₇ is completed, further proceeds to step S _8, the change rate a predetermined value a to input rotation speed of the differential value of the transmission input shaft 50 of the above
After determining that the value is greater than ₁ , the determination result is YE
In the case of S, the process directly proceeds to step S ₉ and the negative pressure actuators 30A, 30 are operated as in the case of step S _2.
B is deactivated and the rotary valve 13 is closed to control the mounting characteristics of the mounting members 7A and 7B in a hard manner (Fig. 6, shift region). In addition, the above step S
₈ , the rate of change a of the input speed is smaller than the predetermined constant value a ₁ (N
If it is O), the process proceeds to step S ₁₁ .

In step S _11, or negative pressure B intake pipe of the engine is the first reference value smaller than the second reference value B ₂ in greater than B ₁ partitioning the operating region of the engine of FIG. 6 If YES (in this case, it means the idling state), the process proceeds to step S ₁₂ , and if NO (in this case, the steady traveling state), the process proceeds to step S ₁₃ . .

In step S _12, first, the negative pressure of the electromagnetic selector valve 46 by switching control to the air-side actuator 30A, 3
Negative pressure actuator 3 by introducing atmospheric pressure to the lower side of 0B
0A, 30B is operated, the position control plate 39
A and 39B are raised to restrain the displacement of the mount members 7A and 7B elastic membranes 11A and 11B, while the rotary valve 13 is opened to allow the movement of fluid between the mount chambers of the mount members 7A and 7B. Make the mounting characteristics soft (Fig. 6, idling area). This effectively absorbs and dampens vibrations during idling.

On the other hand, in step S ₁₃ , the negative pressure actuator 30
A, 30B non-operation, the position control plate 39
A and 39B descend and the elastic films 11A and 11B are controlled to be free, while the rotary valve 13 is opened. As a result, no fluid movement occurs between the mount chambers of the mount members 7A and 7B, and the vibration at this time causes the elastic film 11 to vibrate.
It is absorbed by the deformation of A and 11B, and the mounting characteristics are controlled to a normal state between soft and hard (Fig. 6 steady running area). As a result, the secondary vibration component due to the engine speed that occurs during steady operation is effectively absorbed and damped.

The relationship between the vibration component and, for example, the spring constant corresponding to each engine operation control range is as shown in FIG. 6, and in the end, the control of the mount characteristic in the above-described embodiment depends on each range. Therefore, the optimum spring constant (or damping constant) is selected and set.

Next, the flow chart of FIG. 5 shows the control operation of the mounting device for the power unit according to the second embodiment of the present invention.

In this second embodiment, step S ₉ indicating the steps S ₉ to S ₁₀ portion of the flowchart of Fig. 4 in FIG. 5, S ₁₃
Is obtained by the program changed to S _16, other parts are identical to the program of FIG. 4.

That is, the input rotation speed variation rate a of the transmission input shaft at step S ₈ that is determined is greater than a predetermined value a ₁ and (YES), first, the value of the input rotational speed N at that time in step S ₉ Remember b ₁ . Then, the process proceeds to step S ₁₃ and the rate of change of the input rotational speed N after the elapse of a predetermined time.
It is repeatedly determined whether or not dN / dt is larger than the predetermined value a ₁ . Then, the result is NO, that proceeds to step S ₁₄ at the case where the rate of change is decreased, the change width, i.e. | N-b ₁ | is determined whether or not larger than a predetermined value b On the other hand, in the case of NO, the process directly returns to step S ₁ , while in the case of YES, it is regarded as a gear shift operation and the same operation as steps S ₉ and S _{10 in} FIG. 4 (steps S ₁₅ and S ₁₆ ) is performed. Mount member 7 within a predetermined time (t ₂ seconds)
The mounting characteristics of A and 7B are hard controlled. As a result, the shift state can be detected with high responsiveness from the change in the rotation speed of the transmission input shaft, and the mounting characteristics corresponding to the shift state can be efficiently shifted.

(Effects of the Invention) As described above, the present invention is a power unit in which a power unit including an engine and a speed change mechanism is mounted on a vehicle body through a mount characteristic variable type mounting means specified by a spring constant or a damping constant. In the mounting device, a rotation speed detecting means for detecting an input rotation speed input from the engine to the speed change mechanism, and a change in the input rotation speed more than a predetermined set value is detected based on the detection value of the rotation speed detecting means. And a mount characteristic control means for controlling the mount characteristic of the mount means to the hardware side within a predetermined period when the above is performed.

Therefore, according to the present invention, when a transient and large torque fluctuation occurs during gear shifting, the mount characteristic specified by the spring constant or the damping constant is controlled to the hard (high rigidity) side with reference to the input rotation speed to the transmission. Therefore, the displacement and vibration of the power unit during the torque fluctuation can be effectively prevented with particularly high responsiveness.

[Brief description of drawings]

1 is a block diagram showing the configuration of the entire system of a mounting device for a power unit according to the first embodiment of the present invention, and FIG. 3 is a transmission section of the device according to the first embodiment of the present invention. Partially cutaway sectional view, 4th
FIG. 5 is a flow chart showing the control operation of the control unit of the apparatus of the same embodiment, FIG. 5 is a flow chart showing the control operation of the mounting apparatus of the power unit according to the second embodiment of the present invention, and FIG. It is a mount characteristic view. 1 …… Body 2 …… Power unit 4 …… Engine body 5 …… Transmission 7A, 7B …… Mounting member 13 …… Rotary valve 21 …… Control unit 30A, 30B …… Negative pressure actuator 46 …… Electromagnetic switching valve 50… … Transmission input shaft 51 …… Rotation speed sensor

Claims (1)

[Claims] 1. A mounting device for a power unit, wherein a power unit configured by an engine and a speed change mechanism is mounted on a vehicle body via a mount characteristic variable type mounting means specified by a spring constant or a damping constant, and the transmission mechanism is changed from the engine to the speed change mechanism. The rotation speed detection means for detecting the input rotation speed input to the, and the mounting characteristics of the mounting means when a change in the input rotation speed above a predetermined set value is detected based on the detection value of the rotation speed detection means. A mounting device for a power unit, comprising: mounting characteristic control means for controlling the hardware side within a predetermined period.