JP2841121B2 - Anti-vibration support device for 3-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine mounted on a construction machine such as a backhoe or a bulldozer, and more particularly to an apparatus for supporting a three-cylinder engine in a vibration-proof manner.

[0003]

2. Description of the Related Art Conventionally, as a vibration isolating support structure for a three-cylinder engine mounted on a construction machine of this type, four vibration isolating rubbers are arranged in front, rear, left and right as viewed from a plane, and all of these rubber are used. It is installed at the same height below the center of gravity of the engine unit.

In a tractor, not a construction machine, two right and left rubber cushions are arranged on the front side and one rubber cushion is arranged on the rear side. (See JP-A-59-45219).

[0005]

Generally, vibrations generated in an engine are divided into yawing, pitching, rolling, and vibration. Of these, the co-ordinate force is hardly a problem in a three-cylinder engine, and the other three types of vibrations are not transmitted to the cabin where the operator is located when installed on construction equipment. It is important to do it. Note that yawing is vibration that causes the entire engine unit to swing left and right around the center of gravity when viewed from a plane, and pitching is vibration that swings up and down around the center of gravity similarly when viewed from the side. Rolling refers to a vibration that swings right and left around a center of gravity in a vertical plane when viewed from the rear or the front.

However, in the above-mentioned conventional construction machine in which all four vibration-isolating rubbers are arranged at positions lower than the center of gravity in the front-rear and left-right directions, the problem is not so significant in the case of a small engine. In particular, the large-sized one having a large size has a disadvantage that the vibration damping effect is not sufficient at the time of low idling at about 1000 rpm, and the vibration is easily transmitted to the cabin side. On the other hand, the tractor support structure in which the three vibration-proof rubbers are arranged cannot sufficiently attenuate the vibration of the external force acting on the engine during turning in a construction machine that repeatedly turns the boom or the like. However, there is a drawback that is easily transmitted to the cabin side. SUMMARY OF THE INVENTION It is an object of the present invention to provide an anti-vibration support device in a three-cylinder engine mounted on a construction machine, in which the above-described three types of vibrations can be efficiently attenuated, particularly during low idling.

[0007]

According to the present invention, in order to solve the above-mentioned problems, an engine unit including an engine main body and devices installed integrally with the engine main body is installed via four vibration-isolating rubbers. At
One of a pair of left and right anti-vibration rubbers disposed on the front side with respect to the center of gravity of the entire engine unit and a pair of left and right anti-vibration rubbers also disposed on the rear side with respect to the center of gravity of the engine unit. A pair of anti-vibration rubbers are disposed at a position lower than the center of gravity, and the other pair of anti-vibration rubbers are disposed at a position higher than the center of gravity, and these anti-vibration rubbers pass through the center of gravity of the entire unit as viewed from the side. Alternatively, they are arranged on the same line passing near the center of gravity, and the one having the smallest spring constant of each anti-vibration rubber is arranged in a direction substantially corresponding to the direction of the rolling vibration of the engine unit.

[0008] In the above, the second invention of this application is:
A lid of a flywheel housing located at a rear portion of the engine body is provided with a vibration isolating rubber disposed at a rear side from the center of gravity.

[0009]

In the vibration isolating support device according to the present invention, four vibration isolating rubbers arranged front and rear and right and left are arranged on a line passing through the center of gravity of the entire unit or passing through the vicinity of the center of gravity. By directing the direction of the smallest spring constant in the rolling direction, the natural frequencies of pitching, yawing, and rolling are reduced to reduce vibration. in this case,
Desirably, it can be further reduced by shortening the span between the rubber cushions.

[0010]

1 and 2 showing an embodiment of the present invention, reference numeral 1 denotes an engine main body, and 2 denotes an HST as a transmission for transmitting the power of the engine main body 1 to the body side.
(Hydrostatic transmission), the engine body 1 and the HST 2 constitute an engine unit 3 that is integrally installed on the fuselage side. Reference numeral 4 denotes an airframe arranged on the side of the lower end of the engine unit 3, wherein the front side of the engine body 1 is
The left and right sides of the machine frame 4 are supported via vibration-proof rubbers 5,5. In this case, a V-shaped stay 6 is fixed to the upper surface of the body frame 4 as shown in FIG. 2, and one bracket of the vibration-proof rubber 5 is attached to one of the stays 6 inclined with respect to the engine body 1. It is fixed with bolts 7 that protrude more. As shown in FIG.
On the side surface of the cylinder block 8, another stay 9 having a substantially U-shape as viewed from a plane is fixed by a bolt 10, and one of the stays 9 projecting obliquely downward is provided with a bolt 11 projecting from the other metal fitting of the rubber body. Is inserted and fixed.

On the other hand, on the rear side of the engine body 1, a substantially arch-shaped vertical frame 12 is fixed so as to straddle the upper surfaces of the left and right body frames 4. A bolt 14 protruding from one of the brackets of the vibration-proof rubbers 13 is inserted and fixed. A stay 16 having an L-shaped cross section as viewed from the side is attached to the rear side of the engine body so as to cover the flywheel housing 15 at the rear. Bolts 17 protruding from the other metal fittings of 13 and 13 are inserted and fixed.
The entire engine unit 3 is supported via the switch 13.
In FIG. 1, reference numeral 18 denotes a cooling fan protruding from the front of the engine body 1, and 19 denotes a radiator mounted on the body frame 4 at the front of the cooling fan 18. It should be noted that another hydraulic device or transmission may be installed instead of the HST2.

In mounting the vibration isolating rubbers 5 and 13 as described above, the center of gravity G of the entire engine unit 3 is located at an intermediate point on a line connecting the center of gravity P of the engine body 1 and the center of gravity Q of the HST. As shown in FIG. 1, the front and rear vibration isolating rubbers 5 and 13 arranged with a height difference are arranged so as to pass through the center of gravity G or on a line L passing near the center of gravity. Also, as shown in the figure, the left and right anti-vibration rubbers 5 and 13 are arranged on a line K passing through the center of gravity G or passing near the center of gravity also when viewed from the rear surface. Further, as shown in FIG. 2, each of the vibration isolating rubbers 5 and 13 is arranged so that the XX direction, which is the softest direction, that is, the direction with the largest vibration isolating effect, is the rolling direction. Vibration is effectively attenuated. The reason is as follows.

Generally, in order for the engine to escape the resonance region, the natural frequency of the engine unit 3 must be set to 1 / √2 of the engine rotation. For example, the forced vibration frequency of the three-cylinder engine at a low idle speed of 1000 rpm is 16.7 Hz, but the resonance range at that time is I6.
7 × 1 / √2 = 11.8HZ. The low idle rotation speed is the lowest rotation speed to be used. If the natural frequency of the entire engine unit 3 is set lower than the resonance rotation speed, the resonance rotation speed is deviated from the entire rotation speed.
A structure with less vibration can be obtained. Regarding the yawing vibration and the pitching vibration, the four vibration-isolating rubbers 5 and 13 are arranged in a well-balanced manner on the line L passing through the center of gravity G of the entire unit 3 or passing near the center of gravity G as described above. Can be reduced to less than that. On the other hand, the rolling vibration caused by the explosive power of the engine 1 does not become so low even when the rotation speed decreases,
Therefore, as described above, by directing the one having the smallest spring constant of the anti-vibration rubbers 5 and 13 in the direction of the low link vibration, the vibration is attenuated, and all vibrations generated in the three-cylinder engine are efficiently attenuated. It was something that could be done.

In FIG. 1, the anti-vibration rubber indicated by a two-dot chain line indicates a case where the rear anti-vibration rubber 13 is arranged at the rear of the flywheel housing 15 as necessary. In this case, the front and rear vibration isolating rubbers 5 and 13 are located almost completely on the line L passing through the center of gravity G. Alternatively, it can be added in this manner according to the height of the center of gravity G.

FIG. 3 shows that the rear vibration isolating rubber 13 arranged higher than the center of gravity G is attached to the flywheel housing 1.
The L-shaped stay 21 is attached to the outer surface of the rear cover 20 of the housing 15 by bolts 2.
2, the horizontal portion at the upper end thereof is projected forward, a bolt 17 projecting above the vibration isolating rubber 13 is inserted and fixed in this horizontal portion, and the bolt 14 projecting to the other lower side is shown in FIG. As in the case of 1, it is inserted into the body frame 4 and fixed. The alternate long and short dash line in the drawing indicates a case where the horizontal portion of another stay 21 is projected backward and supported. In this case, the bolt holes for attaching the stays 21 are formed by utilizing the same bolt holes of the housing lid 20, that is,
The most desirable mounting position and angle of the vibration-proof rubber 13 can be selected by using the same housing lid 20 without replacing it.

[0016]

As described above, according to the present invention, four front, rear, left, and right anti-vibration rubbers are arranged on a line passing through or near the center of gravity of the entire unit, and each of the anti-vibration rubbers is connected to its engine. By directing the direction of the smallest spring constant in the rolling direction, the natural frequencies of pitching, yawing, and rolling are reduced to reduce vibration. In this case, desirably, the span can be further reduced by reducing the span between the vibration-isolating rubbers, so that it is possible to obtain an engine support structure for a construction machine with less vibration as a whole. According to the second aspect of the present invention, the mounting structure can be simplified without using a complicated stay by attaching the rear vibration isolating rubber to the lid of the flywheel housing at the rear of the engine body. By changing the position of the bolt holes, you can easily adjust the mounting angle and position of the vibration isolation rubber according to the height of the center of gravity, etc.
It is possible to easily change the stay without changing the shape. Further, by mounting the mounting bolt on the side of the housing lid, the load on the mounting bolt becomes a shearing load, and the number of bolts can be reduced.

[0017]

[Brief description of the drawings]

FIG. 1 is a side view of a support structure of an engine unit.

FIG. 2 is a rear view of a support structure of the engine unit.

FIG. 3 is a side view of a part of another support structure of the engine unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 3 Engine unit 5, 13 Anti-vibration rubber 20 Flywheel housing lid G Center of gravity

Claims (2)

(57) [Claims] The method according to claim 1 engine unit comprising an engine body and equipment to be installed together with the engine body
In the case of installation via four rubber cushions, a pair of left and right rubber cushions disposed on the front side with respect to the center of gravity of the entire engine unit, and two left and right rubber members also disposed on the rear side with respect to the center of gravity. Of the pair of vibration-isolating rubbers, one pair of vibration-isolating rubbers is disposed at a position lower than the center of gravity, and the other pair of vibration-isolating rubbers is disposed at a position higher than the center of gravity. rubber, as well as placing near or centroid passing through the center of gravity of the entire unit when viewed from the side on the same line Ru passing, the smaller the least spring constant of each vibration isolating rubber toward a substantially vibration direction of the rolling vibration of the engine unit An anti-vibration support device for a three-cylinder engine, which is disposed. 2. A three-cylinder engine vibration isolator according to claim 1, wherein a vibration isolating rubber arranged rearward from said center of gravity is attached to a flywheel housing lid located at a rear part of the engine body. Support device. [0001]