JPH0579402A - Engine emission assembly - Google Patents

Abstract

PURPOSE:To increase the resonance frequency of vertical vibration of the engine emission assembly of a transverse engine. CONSTITUTION:In the engine emission assembly of a transverse engine, an engine crank shaft 20 and a differencial drive shaft 22 are set to nearly same positions in vertical direction of the engine. In this way, the center of gravity of the engine is made to agree with that of a differential device with regard to the positions in engine height direction. It is, thus possible to eliminate influence of swinging vibration of the mass of a differencial case 16 so as to increase the resonant frequency of the engine emission assembly in the longitudinal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine and mission assembly having reduced longitudinal vibration.

[0002]

2. Description of the Related Art There is known an engine / mission assembly in which a transaxle integrally provided with a differential device is mounted on a cylinder block of a horizontally mounted engine (an engine mounted with the longitudinal direction of the engine oriented in the vehicle left-right direction). (Kaisho 62-101052).
The invention of the above-mentioned publication discloses that ribs are provided on the differential side of the coupling portion between the engine and the transmission to increase lateral bending rigidity and reduce muffled noise in the vehicle interior.

[0003]

However, in the prior art, as shown in FIGS. 2 and 3, the drive shaft 2 is provided with a differential case 8 of the transaxle 6 in order to avoid the rear flare portion of the engine block 4. The coupling angle was set so as to be above or below when viewed from the engine crankshaft 10.

Therefore, the differential case, which is a heavy object, acts as a mass of the swing vibration when the engine / mission assembly makes a longitudinal vibration (vertical bending vibration in a vertical plane including the crankshaft axis).
The resonance frequency of the engine and mission assembly was lowered, which was a cause of muffled noise in the passenger compartment during acceleration. Further, even if a rib is provided at the engine / mission coupling portion as disclosed in Japanese Utility Model Laid-Open No. 62-101052, the lateral bending rigidity can be improved, but the longitudinal bending rigidity is not so effective.

It is an object of the present invention to increase the longitudinal bending rigidity of a horizontally mounted engine / transmission assembly to reduce longitudinal vibration.

[0006]

The means of the present invention for achieving the above object comprises the following engine and mission assembly. That is, in an engine mission assembly in which a transaxle integrally equipped with a differential device is attached to a horizontally installed engine, the position of the center of gravity of the engine and the position of the center of gravity of the differential device are made to substantially coincide with each other in the engine height direction. An engine and mission assembly characterized by

[0007]

In the engine / mission assembly of the present invention described above, the center of gravity of the engine and the center of gravity of the differential device substantially coincide with each other in the height direction, so that the center of gravity of the differential case within the vertical plane swings with respect to the center of gravity of the engine. Since the arm length becomes zero, no swing vibration occurs, and the relative longitudinal rigidity of the engine / mission assembly is improved. As a result, the resonance frequency of the longitudinal vibration of the engine / transmission assembly rises, the resonance frequency is separated from the engine vibration to the higher side, and the muffled noise in the vehicle interior at the time of high engine rotation is also reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the engine / mission assembly of the present invention will be described below with reference to FIGS. 1 and 4-9. Of these, FIGS. 4 to 6 show a case of a front engine front drive vehicle (FF vehicle) (first embodiment), and FIGS. 7 to 9 show a case of a four-wheel drive vehicle (4WD) (second embodiment). Shown respectively. FIG. 1 is commonly applied to the first and second embodiments.

First, a schematic common structure will be described with reference to FIG. At the rear end in the longitudinal direction of the cylinder block of the engine 12 placed laterally in the vehicle, a transaxle 14 having a differential device and a transmission device integrated is attached. The differential device comprises a differential case 16 with a differential gear assembly installed therein, and the transmission device comprises a transmission case 18 with a transmission installed therein.
6 and the mission case 18 are integrally formed.

The crankshaft 20 extends in the longitudinal direction of the cylinder block of the engine 12 and extends toward the transaxle 1.
4, the drive shaft 22 extends from the differential case 16 and transmits power to the wheels. The axis of the drive shaft 22 is the crankshaft 2.
The coupling angle between the engine 12 and the transaxle 14 is selected so that the axis center of 0 and the height in the vertical direction of the engine are substantially the same. The drive shafts 22 are located just beside the crankshaft 20 and extend parallel to each other. Since the center of gravity of the engine is substantially on the crankshaft 20 and the center of gravity of the differential device is substantially on the drive shaft 22, the center of gravity of the engine and the center of gravity of the differential device are substantially coincident with each other in the engine height direction. By comparing the arrangement of FIG. 1 with the conventional arrangements of FIGS. 2 and 3, the difference from the conventional configuration will become clear.

The cylinder block of the engine 12 has a flare portion 24 which extends to the left and right with respect to the longitudinal direction at the lower portion thereof, and the flare portion near the drive shaft 22 near the rear end in the longitudinal direction of the engine has a drive shaft 22. Not provided to avoid interference with. The flare portion of portion A in FIG. 1 is missing.

Next, a detailed configuration of each embodiment will be described.
As for the first embodiment, as shown in FIG.
2 includes a cylinder block 26, a cylinder head 28 mounted on the cylinder block 26, and a head cover 3 on the upper part.
0 and an oil pan 32 below the cylinder block 26.

In plan view, as shown in FIG.
At the rear end of the cylinder block 26, the housing of the transaxle 14 including the transmission case 18 integrated with the differential case 16 is fastened by the flange portions 34 and 36. As shown in FIGS. 5 and 6, a part of the differential case 16 is laterally offset from the longitudinal direction of the engine, and the drive shaft for driving the front wheels of the vehicle extends to the offset part. The drive shafts 22 are right next to the crankshaft 20 and are parallel to each other.

As shown in FIG. 6, a stiffener 38 composed of a pair of upper and lower ribs is stretched from the side wall of the cylinder block 26 to the flange 34 on the engine side. In the horizontal direction, the rigidity is improved. The stiffener members 38 are provided at the upper and lower positions of the drive shaft 22, respectively.

Further, as shown in FIGS. 4 and 5, a stiffener 40 is also provided between the flange 36 on the transaxle side and the differential case 16, and a stiffener 40 is provided between the engine and the transaxle. The horizontal rigidity is increased.

The second embodiment is shown in FIGS. 7 to 9, and in a 4WD (four-wheel drive) vehicle, the portion of the differential case 42 of the transaxle is integrated with the engine cylinder block 26 and the rib 44. Molding,
Alternatively, the FF of the first embodiment is formed by bolting.
The same function as that of the stiffener members 38 and 40 provided in the vehicle (improvement of rigidity of the connecting portion between the transaxle and the engine) is achieved. Reference numeral 46 is a drive shaft for transmitting power to the rear wheels. Since the other configurations are the same as those of the first embodiment, the description of the configuration of the second embodiment will be omitted by giving the same reference numerals to the corresponding parts.

Next, the operation common to the first and second embodiments will be described. The differential case 42, including the internal differential gear, is a considerable weight, and its center of gravity is approximately on the axis of the drive shaft 22. On the other hand, the rotational force due to the combustion pressure from the piston is transmitted to the crankshaft 20 on the engine side through the connecting rod, and the engine 12 is subjected to longitudinal (vertical) bending vibration about the axis of the crankshaft 20. Bend and vibrate horizontally.

If the conventional device shown in FIGS. 2 and 3 is used,
If the center of gravity of the differential device (approximately the axis of the drive shaft) is largely separated in the vertical direction from the center of gravity of the engine vibration system (almost the axis of the crankshaft), the center of gravity of the differential device will be in the vertical plane when the engine 12 vibrates vertically. It will show a swinging motion of swinging back and forth in the longitudinal direction of the engine. This means that the differential mass acts as an inertial mass to reduce the resonance frequency of longitudinal bending vibration of the engine / mission assembly.

On the other hand, in the present invention, since the drive shaft 22 is located at substantially the same height as the crankshaft 20 in the vertical direction of the engine, the arm length of the center of gravity of the differential device is zero, and The differential device will not vibrate. Therefore, it means that the resonance frequency of the longitudinal bending vibration of the engine / mission assembly is increased.

In the lateral direction, the axis of the drive shaft 22 is farther from the axis of the crankshaft 20 than in the conventional case, so that the resonance frequency of lateral bending vibration tends to decrease. However, in the present invention, in both the first embodiment and the second embodiment, since the connecting portion between the transaxle and the engine is reinforced in the horizontal direction by the stiffener members 38, 40, 44, the lateral bending vibration is generated. The resonance frequency of does not decrease.

In order to check the degree of improvement in rigidity according to the present invention, the resonance frequency in each case was analyzed and obtained by the finite element method. The results are as follows. Horizontal bending Vertical bending Case A 235 Hz 254 Hz Case B 223 Hz 263 Hz Case C (invention) 228 Hz 271 Hz Case D (invention) 254 Hz 277 Hz However, Case A: the drive shaft is below the crankshaft (in the case of FIG. 2). Case B: The drive shaft is above the crankshaft (in the case of FIG. 3). Case C: The drive shaft is right next to the crank shaft (in the case of FIG. 1), but without the stiffener member. Case D: The drive shaft is right next to the crank shaft (in the case of FIG. 1), but with a stiffener member.

As is clear from the above analysis, according to the present invention, the resonance frequency of longitudinal bending vibration is about 10-2 as compared with the conventional case.
It can be seen that the frequency increases by 0 Hz. Further, when the stiffener member is provided, the resonance frequency of lateral bending vibration can be increased.

Generally speaking, in order to avoid resonance of the engine / mission assembly in the normal operating speed range, the natural frequency of the engine / mission assembly is set to be about less than the engine vibration (about 200 Hz) that appears during acceleration or high speed rotation. Although it is set to the 20% higher side, in the present invention, the resonance frequency is further increased by 10 to 20 Hz, so that the vibration amplitude of the engine / mission assembly is suppressed and the muffled noise in the passenger compartment is also reduced.

Further, the added stiffener members 38, 4
By 0 and 44, the joint rigidity in the lateral bending direction and the twisting direction is also improved, and the muffled noise in the vehicle interior due to the vibrations thereof is also reduced.

Further, in the case of a 4WD vehicle, it has been difficult to tighten due to interference with the transfer case in the past, but in the present invention, the tightening portion on the left side of the rear flare portion of the cylinder block can be omitted, and the workability of assembling is improved. Has improved.

[0026]

According to the present invention, in the engine / transmission assembly of a horizontal engine, the center of gravity of the engine and the height of the center of gravity of the differential device are substantially aligned with each other in the vertical direction of the engine. The resonance frequency of the longitudinal vibration of the engine / mission assembly can be increased, and as a result, the muffled noise in the passenger compartment can be reduced.

[Brief description of drawings]

FIG. 1 is a basic front layout view of an engine / mission assembly of the present invention.

FIG. 2 is a front layout view of an example of a conventional engine / mission assembly.

FIG. 3 is a front layout view of another example of a conventional engine / mission assembly.

FIG. 4 is a side view of the engine / mission assembly according to the first embodiment of the present invention.

FIG. 5 is a bottom view of the engine / mission assembly according to the first embodiment of the present invention.

FIG. 6 is a perspective view of the engine / mission assembly according to the first embodiment of the present invention.

FIG. 7 is a side view of an engine / mission assembly according to a second embodiment of the present invention.

FIG. 8 is a plan view of an engine / mission assembly according to a second embodiment of the present invention.

FIG. 9 is a perspective view of an engine / mission assembly according to a second embodiment of the present invention.

[Explanation of symbols]

 12 engine 14 transaxle 16 differential case 18 mission case 20 crankshaft 22 drive shaft 26 cylinder block 34 flange part 36 flange part 38 stiffener member 40 stiffener member 42 differential case 44 rib

Claims (1)

[Claims] 1. In an engine / transmission assembly in which a transaxle integrally provided with a differential device is attached to a horizontally installed engine, the position of the center of gravity of the engine and the position of the center of gravity of the differential device are
An engine and mission assembly characterized by making the engine height direction almost the same.