JPS63111265A - Cylinder block structure of engine with balancer - Google Patents

Abstract

PURPOSE:To improve the rigidity of a cylinder block and to prevent seizure of a balancer bearing by solidly forming a crank bearing portion, a balancer bearing portion and ribs connecting therebetween by material having higher rigidity than light alloy and casting these portions in light alloy. CONSTITUTION:A cylinder block 1 comprises a cylinder portion 5 and a skirt portion 8, wherein balancer bearings 9p, 9q respectively supporting balancers 7p, 7q are provided on the right and left side walls of the skirt portion 8. In this case, as the respective balancer bearings 9p, 9q are formed in the same manner on the right and left, only one balancer bearing will be explained. The balancer bearing is formed as a part of a case-iron frame W having high rigidity, which is solidly formed extending over a crank bearing portion 12b, vertical ribs 15p, 15q and inclined ribs 16p, 16q, and case into the skirt portion 8 made of light alloy. Fastening bolts 10p, 10q are screwed in the upper and lower portions of the balancer bearing 9p to tense an annular portion W1 of the frame W.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of an engine cylinder block equipped with a balancer that cancels the unbalanced inertia force of the engine.

[Prior art] A balancer is provided to cancel the unbalanced inertial force of the engine, which excites the bending vibration mode in the direction perpendicular to the output shaft of the engine/transmission system, which causes noise and vibration in automobiles. is well known. In order to rotatably support such a balancer, a balancer bearing is usually provided in the skirt portion of the cylinder block.For example, two balancers and a balancer bearing that supports them are arranged around the outer circumference of the cylinder bore. The cylinder block was made into a more compact shape (Japanese Patent Application Laid-Open No. 1986-
106248) etc. have been proposed.

On the other hand, it is well known that in order to reduce the weight of an engine from the standpoint of improving fuel efficiency, a cylinder block made of a light alloy whose main component is aluminum is used.

However, although such light alloys have the advantage of being lightweight, they have the disadvantage of low rigidity. Therefore, in light alloy cylinder blocks such as the front 5 cylinder block with a parallel bearing installed in the spout section,
As shown in FIG. 3, in the cylinder block 31,
The explosive load is applied downward to the crank bearing 32, and the inertia of the left and right balancers is applied to the balancer bearing 3, respectively.
3.34, the cylinder block 31 having the original shape shown by A is deformed into the shape shown by B, and as a result, the crank bearing 32 and the left and right balancer bearings 33 and 34 are deformed, respectively. and balancer bearing 33.
34 are respectively displaced in the direction of the crank bearing 32. At this time, for example, the model calculation shows that the lateral displacements of the left and right parallel bearings 33, 34 are 25 μm and 24 μm, respectively, and the vertical displacements are 69 μm and 79 μm, respectively.

However, since the oil clearance of the balancer bearing 33.34 is generally 50 to 80 μm, the above displacement amount may exceed the oil clearance, and in this case, there is a problem that the balancer bearing 33.34 may seize. It was hot. In order to prevent this, increasing the wall thickness, adding ribs, etc. have been proposed, but these methods require layout improvements and have the problem of increasing the size of the cylinder block and increasing cost.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems.
Deformation of the crank bearing and deformation and displacement of the palancer bearing due to the explosive load applied to the crank bearing and the inertia force of the balancer applied to the palancer bearing can be suppressed, and seizure of the palancer bearing can be reliably prevented. The purpose of the present invention is to provide a light alloy cylinder block for a compact engine with a balancer.

[Structure of the Invention] In order to achieve the above object, the present invention provides a light alloy cylinder block for an engine with a balancer, in which a balancer bearing is disposed laterally outward of the crank bearing when viewed in the cylinder row direction. A bearing part, a rib connecting the crank bearing part and the bottom deck, a balancer bearing part, and a rib extending in a direction connecting the center line of the balancer bearing and the center line of the crank bearing part, and extending between the balancer bearing and the crank bearing. The ribs connecting the parts are integrally formed with a material having higher rigidity than the light alloy mentioned above,
Provided is a cylinder block structure for an engine with a balancer, which is characterized by being cast in a light alloy.

[Effects of the Invention] According to the present invention, a crank bearing portion, a balancer bearing portion, a rib connecting the crank bearing portion and a bottom deck,
The rib that connects the crank bearing and the palancer bearing is integrally formed from a highly rigid material such as cast iron, and this is cast into a light alloy as a frame to form the cylinder block, increasing the rigidity of the cylinder block. The plate thickness of the bulkhead such as the crank bearing can be reduced, making it possible to make the cylinder head more compact.The improved rigidity also prevents deformation of the crank bearing and balancer bearing due to explosive loads and inertia of the balancer. It is possible to suppress the displacement of the bearing and reliably prevent seizure of the parantor bearing.

Preferably, the frame portion of the balancer bearing portion is bolted to the light alloy portion of the skirt portion of the cylinder block, thereby pulling the balancer bearing portion laterally outward and pulling the rib connecting the balancer bearing portion and the crank bearing portion. By applying stress, this tensile stress can more effectively suppress deformation or displacement of the palancer bearing, thereby making it possible to more reliably prevent seizure of the palancer bearing.

[Example] Examples of the present invention will be specifically described below.

As shown in FIG. 1, the cylinder block 1 includes a cylinder part 5 whose upper end and lower end grip a cylinder liner 4 fitted into a top deck 2 and a bottom deck 3, respectively;
Crankshaft 6, connecting rod (not shown)
A skirt portion 8 that defines a space 20 inside for storing etc.
It basically consists of.

In the skirt portion 8, two wires are provided at approximately midpoint in the vertical direction between the left and right walls in FIG. balancer 7 p, 7 q
Parallel bearing 9p that supports the shaft.

9q is provided. These left and right balancer bearings 9p and 9q in FIG. 1 have almost the same configuration and are symmetrical to each other. Therefore, only the balancer bearing 9p on the left side in FIG. 1 will be described as a representative. A crank bearing portion 12b, which will be explained later, and a vertical rib 15p,
It is formed as a part of a highly rigid cast iron frame W that is integrally formed astride the slanted ribs i6p and 16q, and is cast into the light alloy skirt portion 8 of the cylinder block l. The above frame W has a parallel bearing 9
It is formed into an annular shape at the part p, and the frame W
From the annular part Wl, the upper part W enters slightly above and slightly below the skirt part 8, respectively.

and a lower infiltration part W3 (hereinafter referred to as the palancer bearing 9p, the upper part of the skirt part 8, and the lower infiltration part W).

The combined part with the part having W3 is the balancer bearing part 9.
It's called 'p. ). Then, at a position above the balancer bearing 9'p of the balancer bearing 9'p, the wall of the inner heparancer bearing 9'p is moved from the outside of the skirt part 8.
A tightening bolt 10p is screwed through '. The tightening bolt lOp does not contact the light alloy portion of the wall of the balancer bearing portion 9'p outside the upper insertion portion W2 of the frame W, and on the other hand, the upper insertion portion W and the balancer bearing portion 9′p The upper penetration part W of the wall frame W is designed to be screwed to the inner light alloy part, and the tightening bolt lO
By tightening p, the upper penetration part W of the frame W,
is facing outward in the axial direction of the top tightening bolt (upper left direction in Figure 1)
It seems that people are drawn to it. Similarly, at a position below the balancer bearing 9p of the balancer bearing 9'p, a tightening bolt lip is screwed through the wall of the balancer bearing 9'p from the outside of the skirt part 8 to the inside.
The tightening bolt 11p, like the tightening bolt lOp, is adapted to pull the lower penetration portion W of the frame W outward in the axial direction of the tightening bolt lip (in the upper left direction in FIG. 1).

Therefore, by tightening the above two tightening bolts lOp and lip, respectively, the annular portion W+ (parancer bearing 9p) of the frame W is pulled substantially outward in the axial direction of the tightening bolts top and ttp. .

The structure around the balancer bearing 9q on the right side of FIG. 1 is also similar to the structure around the left balancer bearing 9p, and corresponding members are given the same numbers and the subscript q.

Meanwhile, in the space 20 defined inside by the skirt part 8 of the cylinder block 1, there are a bearing gap 12a and a crank bearing part 12b formed as a part of the cast iron frame W. A crank bearing 12 is provided which is joined by tightening mounting bolts 13p and 13q, and the crank bearing 12 rotatably supports the crankshaft 6. Above.

The rank bearing portion 12b has a straight line connecting the mounting bolts 13p, 13q and the cylinder head mounting bolts 14p, 14q for mounting the cylinder head (not shown) to the cylinder block 1, respectively, near the left and right ends thereof. It is connected to the bottom deck 3 via vertical ribs 15p, 15q formed by a part of the frame W, which are provided by extending from the top, and left and right balancer bearings 9p, 9q.
The parallel bearings 9 p and 9 are connected to the parallel bearings 9 p and 9 via inclined ribs 16 p and 16 q formed as part of the frame W extending on the respective straight lines connecting the center line of the crank bearing 12 and the center line of the crank bearing 12 . q (skirt portion 8).

The crank bearing portion 12b, vertical ribs 15p, 15q, and inclined ribs 16p, 16q formed as a part of the cast iron frame W are integrally cast into a light alloy cylinder block l. With such a configuration,
The increase in the wall thickness of the bulkhead part of the cylinder block l is suppressed, the cylinder block l is made more compact, and by being reinforced by the highly rigid frame W,
The rigidity of the cylinder block l is increased to suppress deformation caused by the explosive load or the inertial force of the balancers 7p and 7q. Furthermore, the crank bearing part 12b connects to balancer bearing parts 9'P and 9'q (skirt part 8) at both left and right ends via horizontal ribs 17p and 17Q formed only of light alloy and extending in the left-right direction, respectively. combined with
The rigidity of the cylinder block l in the left and right direction is increased.

Note that oil pan rails 18p and 18q are provided at the lower end of the skirt portion 8 on the left and right sides, respectively, to which oil pans (not shown) are attached.

Hereinafter, the functions of this embodiment will be explained one by one with reference to FIG. It should be noted that since the left and right parts of the cylinder block l have the same structure and function, only the left part will be described.

First, as mentioned in the official document, the cylinder block 1 is reinforced with a frame W around the bulkhead part to increase its rigidity, so a downward explosive load F1 is applied to the crank bearing 12.
or the balancer 7p is attached to the balancer bearing 9p.
Even if a downward inertial force F, . is applied, the deformation of the cylinder block l as shown in FIG. 3 is suppressed.

Furthermore, by tightening the two tightening bolts 10p and 11p, an inward force Fs is applied to the light alloy portion of the balancer bearing portion 9°p outside the frame W, respectively.

At the same time that F6 acts, frame W acts as a reaction.
Forces F, F, which are directed outward in the axial direction of the tightening bolts top and lip are generated in the upper penetration part W and the bottom penetration part W3, respectively, and the resultant force of F and F4 causes the inclined rib 16p to move outward. The pulling force is F, and this force F? The direction of the inclined rib 16 is determined by the resultant force of the explosive load F1 and the inertia force F of the balancer 7p.
Since the direction of the resultant force F8 acting to cause displacement of the balancer bearing 9p is opposite to that of the resultant force F8, which acts to cause displacement of the balancer bearing 9p, the force that displaces the balancer bearing 9p in the direction of the central axis of the crank bearing 12 at the time of explosion is canceled out by the above-mentioned tensile force F, and the balancer bearing 9p is Displacement of the bearing 9p can be effectively suppressed.

As described above, according to this embodiment, the rigidity of the cylinder block 1 is strengthened by frame casting, and the tightening bolts 10p, lip
By reducing the stress that displaces the balancer bearing 9p due to the tightening force, deformation of the crank bearing and deformation and displacement of the balancer bearing are effectively suppressed, and seizing of the balancer bearing is reliably prevented.

It should be noted that the engine in this embodiment is provided with a function of varying the rotational phase difference between the crankshaft and the balancer, so that when an explosive load is applied to the crank bearing, the rotational phase of the balancer is shifted to give an outer component to the inertial force. Alternatively, it is more preferable to shift the rotational phase of the balancer at all times of high rotation so that the force that causes deformation or displacement of the balancer is suppressed by the above-mentioned outer component of the inertial force of the balancer.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a light alloy cylinder block for an engine with a balancer, showing an embodiment of the present invention. FIG. 2 is an enlarged schematic view of the area around the balancer bearing in FIG. 1, showing the force acting on the balancer bearing. FIG. 3 is a schematic diagram showing deformation of the cylinder block due to the explosion load and the inertia force of the balancer. l...Cylinder block, 3...Bottom deck, 6
...Crankshaft, 7p, 7q...Balancer, 9p
, 9 q... Balancer bearing, 9' p, 9' q.
・・Balancer bearing part, 12・・Crank bearing, 12a・
...Bearing cap, 12b...Crank bearing part, 15p, 15q...Vertical rib, 16p, 16q...
・Slanted rib, W...frame.

Claims (1)

[Claims] (1) In a light alloy cylinder block of an engine with a balancer, in which the balancer bearing is disposed laterally outward of the crank bearing when viewed in the cylinder row direction, the crank bearing and
a rib that connects the crank bearing and the bottom deck;
The balancer bearing portion and the rib that extends in the direction connecting the center line of the balancer bearing and the center line of the crank bearing portion and connects the balancer bearing and the crank bearing portion are made of a material having higher rigidity than the above-mentioned light alloy. An engine cylinder block structure with a balancer that is integrally formed with aluminum and cast in light alloy.