JPS5828456B2 - Balancer shaft bearing structure - Google Patents

Abstract

PURPOSE:To offer a bearing contruction which can enjoy secure oil supply even at the time of high speed operation by providing a means to make the lubrication hole extending in the radial direction in the on the oil bearing supply side, shorter than the one on the load side. CONSTITUTION:In a balancer shaft A having lubrication holes 06, 010 provided in the radial direction in the bearings 04, 05 on the oil supply side and the load side, respectively, and extending from a lubrication hole 09 excavated in the axial direction, the diameter 6' of the oil supply side bearing shall be larger than that of the load side bearing as well as a groove 12 with a smaller diameter that the load side bearing. The lubrication hole 6 excavated in the oil supply side bearing in the radial direction is put into communication with the abovementioned groove 12 so that the length of this hole 6 becomes smaller than that of the lubrication hole 010 excavated in the abovementioned load side bearing in the radial direction. In this construction, the fed oil flows as shown by an arrow 07, reaching the load side bearing 05 through the lubrication hole 6 is smaller than that of the lubrication hole 010, so that the centrifugal force at the time of high-speed operation can be suppressed small and a secure oil feeding can be expected.

Description

[Detailed description of the invention] The present invention relates to a bearing structure for a balancer shaft.

As an example of the structure of a conventional balancer shaft, the secondary balancer shaft of a 4-cycle in-line 4-cylinder engine is shown in FIG.

01a, Olb is the balancer shaft, 02 is the crankshaft, 03
a, 03b are balance weights, 04a, 04b
is the bearing on the oil supply side, 05a and Q5b are the bearing on the load side,
Balancer shafts 01a and 01b are used to balance the secondary inertia force.
rotate in opposite directions at a speed 2ω that is twice the rotational speed ω of the crankshaft 02.

FIG. 1 is an enlarged sectional view showing the bearing structure of the balancer shaft, and the diameter of the bearing part of the balancer shaft on the oil supply side bearing 04 side is slightly larger than the bearing part diameter of the load side bearing 05, and it has a shape that can be extracted. It is said that

Further, oil holes 06 and 010 are formed extending radially from the oil hole 09 along the axis, and oil supply indicated by arrow 07 reaches the load-side bearing surface through the oil holes 06, 09, 010.

In this configuration, the diameter of the bearing part is slightly larger on the oil supply side, and the rotation is twice that of the crankshaft, so the centrifugal force at high speeds becomes greater than the oil supply pressure, making oil supply difficult and potentially causing burnout.

The purpose of the present invention is to focus on the above points and to provide a bearing structure that can reliably supply oil even at high speeds.The main feature of this invention is that the oil hole extending in the radial direction of the bearing on the oil supply side is A means for making the length shorter than that of the load side bearing part is provided.

This reduces the centrifugal force generated in the oil hole on the oil supply side, and ensures reliable oil supply.

Embodiments of the present invention will be described below with reference to the drawings.

2 and 3 show one embodiment of the present invention, FIG. 2 is a sectional view showing the oil supply side bearing part of the balancer shaft, and FIG. 3 is a sectional view taken along the X-Y line in FIG. 2. be.

The difference from the conventional example is the structure of the bearing on the oil supply side.

In the figure, the diameter of the bearing on the oil supply side of the balancer shaft is larger than the diameter of the bearing on the load side, similar to that in Figure 1, and the shaft body can be extracted from the crankcase.

12 is a concave groove formed in the oil supply side bearing part of the balancer shaft;
In other words, it is an oil groove.

Reference numeral 6 denotes an oil hole that extends in the radial direction from the oil hole provided along the axis of the balancer shaft in the oil supply side bearing portion, and communicates with the concave groove 12.

The length a of the oil hole 6 can be adjusted appropriately, and is shorter than the oil hole (010 in FIG. 1) extending in the radial direction of the load side bearing.

In the case of the above configuration, oil supply flows as shown by arrow 07 (see FIG. 1), and the oil supply flows through the oil hole 6. It reaches the load-side bearing (05 in FIG. 1) through an oil hole provided along the axis and an oil hole 010 in the load-side bearing.

In this case, since the length a of the oil hole 6 of the oil supply side bearing is shorter than the length of the oil hole 010 of the load side bearing, the centrifugal force at high speed is also small and oil can be reliably supplied.

As described above, the present invention has the following effects.

(1) By making the length of the oil hole in the oil supply side bearing of the balancer shaft shorter than the length of the oil hole in the load side bearing, oil can be reliably supplied even at high speeds.

(2) Due to the difference in oil hole length, a higher oil pressure than the oil supply pressure can be obtained in the load-side bearing portion by the amount of centrifugal oil pressure, which is particularly effective during high-speed rotation.

Although the above description has been made regarding the secondary balancer axis, it can of course also be applied to the primary balancer axis.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the bearing structure of a conventional balancer shaft.
Fig. 2 is a cross-sectional view showing the structure of the bearing on the oil supply side of the balancer shaft according to one embodiment of the present invention, Fig. 3 is a cross-sectional view taken along the line X-X in Fig. 2, and Fig. 4 is a cross-sectional view showing the structure of the balancer shaft. FIG. 3 is a sectional view of the crankcase shown in FIG. 01... Balancer axis, 03... Balance weight,
04...Oil supply side bearing, 05...Load side bearing, 06,
6゜os, oio...oil hole, 12...concave groove.

Claims (1)

[Claims] 1. In a balancer shaft that has an oil hole extending radially from the oil hole provided along the shaft center in the oil supply side bearing part and the load side bearing part, the diameter of the oil supply side bearing part is made larger than that of the load side bearing part. At the same time, a concave groove having a smaller diameter than the load side bearing is provided, and an oil hole extending in the radial direction of the oil supply side bearing is communicated with the concave groove, so that the length of the oil hole is changed in the radial direction of the load side bearing. A bearing structure of a balancer shaft characterized by being configured to be shorter than the length of an extending oil hole.