JPS62251414A - Cylinder block structure for engine - Google Patents

Abstract

PURPOSE:To effectively utilize space, by spreading the upper of cylinder block side walls, which form swollen parts with built-in balancer shafts, in the lengthwise direction of an engine to form spread chambers and forming an oil return passage through the spread chamber. CONSTITUTION:A pair of right and left balancer shafts 4, 5, built in swollen parts 8 of cylinder block side walls 1c, are provided to be arranged in upper both sides of a main bearing part 2 of a cylinder block 1. In the cylinder block side walls 1c, spread chambers 1d, which are formed protruding to the outside while spreading in the lengthwise direction of the cylinder block 1, are provided to be arranged in the upper of the swollen parts 8. An oil return passage 18, which extends in the vertical direction, passes through the spread chamber 1d, and the spread chamber 1d is opened downward so as to constitute one part of said oil return passage 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to a cylinder block structure for an engine in which a balancer shaft is built into the cylinder block.

(Prior Art) Conventionally, for example, as seen in Japanese Patent Publication No. 57-44863, imaging due to the secondary reciprocating inertia force generated in the vertical direction during the operation of a multi-cylinder engine has been developed. In order to counteract this, a technique is known in which a balancer shaft having a balance weight is rotated in conjunction with the rotation of the crankshaft.

Further, in order to incorporate the balancer shaft left into the cylinder block as described above, the cylinder block N wall is generally formed to bulge outward and is installed within this bulge. On the other hand, an oil return passage is formed in the cylinder block in the vertical direction so that oil from the cylinder head is returned to the oil pan.

(Problem to be Solved by the Invention) When the balancer shaft is built into the side wall of the cylinder block as described above, the eccentric load of the balance quake as the balancer shaft rotates causes a large load on its bearing part. Therefore, it is necessary to improve the support rigidity.

On the other hand, the return oil flowing down from the cylinder head through the oil return passage formed in the cylinder block is
The problem is that the oil enters the crankcase immediately from the oil return hole and is agitated by the crank shirt 1-, causing air to get mixed into the oil and make it turbid. Furthermore, oil mist is mixed into the blow-by gas, increasing the oil 8'S cost.

In view of the above circumstances, the present invention provides a cylinder block structure for an engine that improves the rigidity of the side wall of the cylinder block that incorporates the balancer shaft, prevents turbidity of return oil, and separates blow-by gas from A-il. 1] The purpose is to:

(Means for solving the problem) The cylinder tab 1 of the present invention has a balance 12
The cylinder block side wall above the bulge is expanded in the longitudinal direction of the engine to form an enlarged chamber, and an oil return passage is connected from above. There are four types characterized in that the expansion chamber is formed through the expansion chamber.

(Function) In the above cylinder block structure J3, an enlarged chamber is formed above the bulge of the cylinder block that houses the balancer shaft, and this enlarged chamber improves the rigidity of the side wall of the cylinder block, which in turn supports the balancer shaft. Improves rigidity. In particular, the expansion chamber allows reinforcement of the cylinder part of the cylinder block and the connecting joint part of a part of the Nuka-1.
Improves rigidity.

In addition, the direction of the return oil flowing down the oil return passage is changed in the enlarged chamber formed midway, and the flow velocity is moderated, and the number of oil ports that directly hit the crankshaft is reduced, eliminating oil turbidity due to air intrusion. Furthermore, the generation of oil mist is reduced, and the amount of oil mixed into the blow-by gas is reduced. Roughly speaking, the blow-by gas flows upward through the enlarged chamber, but the oil separation effect caused by the change in passage area and direction caused by the enlarged chamber separates and removes the oil mixed in the blow-by gas, reducing the number of oil consumption ports.

(Example) The present invention will be described in detail below with reference to the drawings.

Figure 1 is a sectional view of the cylinder block at the center of the bore, Figure 2
The figure is a sectional view of the bulkhead portion between the bores, FIG. 3 is a side view, FIG. 1 is a sectional view taken along the line I--I in FIG. 3, and FIG.

The cylinder block 1 has a plurality of bore portions 1a arranged in series in the upper center thereof, and a piston (not shown) is fitted into the bore portion a so as to be able to reciprocate up and down.

Further, the cylinder block 1 has a skirt portion 1b extending on both sides of the lower part, and a main bearing portion 2 for supporting a crankshaft 25 (see FIG. 4) is disposed below the bore portion 1a. The main bearing part 2 is installed between the cylinders of the bore part 1a arranged in series, and the main bearing part 2, the bore part 1813, and the skirt part 1b are connected by a bulkhead part 3 in the form of a partition wall.

Furthermore, a pair of left and right balancer shafts 4.5 are disposed on both sides of the upper part of the main bearing portion 2, which are built into the bulge portion 8 of the cylinder block side wall 1C. These left and right balancer shafts 4.5 are eccentrically formed balance weights 4a.
, 5a, front and rear ends and intermediate journal portions 4b,
5b is supported in a bearing 6.6 formed in the bulkhead part 3. The bulkhead portion 3, which is provided with bearing portions 6, 6 for supporting the balancer shirts 1-4, 5, is formed with through holes 7, 7 which communicate the space portions on both sides.

Furthermore, in the cylinder block fill wall 1C, an enlarged chamber 1d that is formed to protrude outward and expand in the longitudinal direction of the cylinder block 1 is disposed above the bulge 8 that houses the balancer shaft 4.5. It is set up. In the right side of FIG. 2, the enlarged chamber 1d has an oil return passage 18 extending in the vertical direction passing therethrough, and is open at the bottom so as to constitute a part of the oil return passage 18.

On the other hand, the enlarged chamber 1d on the left side similarly has a blow-by gas passage 17 extending vertically, and has an n-opening at the bottom so as to constitute a part of the blow-by gas passage 17.

A bypass passage 9 through which cooling water flows is formed below the bore portion 1a of the cylinder block 1, extending in the longitudinal direction of the cylinder block 1 and integrally formed with the bore portion 1a. Also, the bore portion 1 on the opposite side to this bypass passage 9
An oil gear lary 10 that similarly extends in the longitudinal direction of the cylinder block 1 is formed at the lower part of the cylinder block 1. The bypass passage 9 and the oil gear rally 10 are connected to the enlarged chamber 1.
d and 1d are formed adjacent to each other inwardly.

The lubricating oil is supplied to the bearings 6, 6 of the balancer shafts 4, 5 as shown in FIG.
is formed in the bulkhead portion 3, and this A-ile feeding passage]
A branch oil passage 12 horizontally branched from the middle of the shaft 1 is connected to the bearing parts 6.6 on both sides, and lubricating oil is pumped through this branch oil passage 12 to the bearing parts 6.6 on both sides.

J3, a cooling water passage 14 constituting a water gauge 12 is provided on the outer periphery of the bore portion 1a of the cylinder block 1. On the other hand, an inlet 9a of the bypass passage 9 is opened in the side surface of the cylinder block 1.
connected to a water pump (not shown) installed in the
This thermostat 15 closes the communication to the four-way pump. In addition, thermostat case 16
A heater return passage connection port 16a is formed in the heater return passage connection port 16a.

On the other hand, the drive mechanism for the balancer shafts 4 and 5 is as shown in FIG. A shaft 22 is provided in the cylinder block 1, and a chain sprocket 23 that rotates together with the gear 21 marked with # is fixed to the intermediate shaft 22. Furthermore, a chain sprocket 24 is provided at the front end of the balancer shaft 5 on the right side.

The chain sprocket 26 of the crankshaft 25, the intermediate shaft 22 and the right balancer shaft 5
A chain 27 is wound around each of the chain sprockets 23 and 24, and with respect to the rotation of the crankshaft 1 shift 25, the right balancer shaft 1 shift 5 remains unchanged, and the left balancer shaft 4 is rotationally driven via the intermediate shaft 22. The balancer shafts 4.5 are driven to rotate in mutually opposite directions. In addition, this balancer shaft 4.5 is
It is driven to rotate at twice the speed of the crankshaft 25, and its rotational phase is stepped such that the balance weights 4a, 5a are eccentrically positioned downward when the piston is at the top dead center or bottom dead center. Note that 28 is a chain tensioner, and 29.30 is a guide member.

In the above structure, the bulging part 8 housing the balancer shafts 4 and 5 on the cylinder block side u1c is formed so that the thermostat case 16 is continuous on the front end side, increasing rigidity, and from the middle part to the rear part. The expansion chamber 1d is formed continuously to increase rigidity.

Further, the enlarged chamber 1d of the oil return passage 18 reduces the flow rate of oil, and when the engine is in a cold open state, the return oil warmed by the engine operation comes into contact with the bypass passage 9. This heats the cooling water flowing inside the engine, making the upper temperature limit faster and improving warm-up performance.

(Effect of the invention) According to the present invention as described above, one foot of the balancer can be
ia! By forming an enlarged chamber by using the upper space +51 of the bulging part, the formation of this enlarged chamber is
・In addition, the rigidity of the entire cylinder block can be improved by connecting the cylinder block side wall and the bulge part with the upper and 2 enlarged chambers and reinforcing the joints in particular. Stiffness can be increased.

In addition, the expansion chamber reduces the flow rate of the return oil and reduces agitation by the crankshaft, thereby suppressing the incorporation of air bubbles into the oil and separating the oil from the blow-by gas.

[Brief explanation of drawings]

Fig. 1 is a sectional view at the center of the bore of the cylinder block I3 according to an embodiment of the present invention, Fig. 2 is a sectional view at J3 between the bores of the cylinder block, Fig. 3 is a side view of the cylinder block, Fig. 4 is a diagram showing the basic δ11 driving mechanism of the balancer shaft. 1...Cylinder tab [1 tsuk 1a...]
Boa part 1b...Skirt part 1C...
...Side wall 1d...Enlargement room 2...
...Main bearing part 3...Bulkhead part

Claims (1)

[Claims] (1) A balancer shaft equipped with a balance weight is housed in a bulge formed on the side wall of the cylinder block, and the side wall of the cylinder block above the bulge is expanded in the longitudinal direction of the engine to form an enlarged chamber. An engine cylinder block structure characterized in that an oil return passage is formed through the enlarged chamber.