JPS58148209A - Cam shaft driving gear - Google Patents

Abstract

PURPOSE:To prevent a shock to a cam shaft driving system, by providing a shock absorbing member to a driven member driving a cam shaft in a cam shaft driving gear of an internal-combustion engine. CONSTITUTION:Power of a crankshaft 3 is transmitted to a driving gear 20 fixedly provided to a cam shaft 10 through a gear 14, reduction gear 15 and idle gear 16, and the gear 20 is driven to rotatively drive the cam shaft 10. At such meshing, a shock is transmitted to the shaft 10 and to a gear driving system through the gear 20 to generate a cause of wearing or the like in the gear driving system, and the gear 20 is formed to double construction while a damper rubber 25 is provided between the cam shaft and a power transmission meshed part of gear teeth. Accordingly, a shock of the shaft 10 is relaxed and absorbed by the rubber 25 and transmission of the shock to the teeth is isolated in this part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a camshaft drive device for an internal combustion engine.

A type that uses a camshaft to control the opening and closing of the intake and exhaust valves of a vehicle's internal combustion engine connects the engine output shaft and the camshaft via a chain, sprocket, gear, etc., and drives the camshaft to rotate. The cam part engages with a rocker arm that presses the bushing rod, suppresses and releases the bushing rod against a spring, etc., and opens and closes the intake and exhaust valves.

In this type of internal combustion engine, the cam portion of the camshaft periodically collides with the compressed valve system, and the impact is transmitted to the drive system through the camshaft, causing wear and other causes, and damage to the drive system. Improvements are desired in terms of improved durability.

The present invention has been made to improve the above problems, and its purpose is to provide a buffer member to the driven member that drives the camshaft, to buffer and absorb the impact transmitted from the camshaft to the drive system of the camshaft. An object of the present invention is to provide a camshaft drive device that protects the drive system and improves its lifespan and durability.

Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory longitudinal sectional side view of an internal combustion engine, and FIG. 2 is a diagram.

The embodiment shows a four-cylinder engine with two cylinders in the front and rear, which has a sideward V-shape and has a horizontal crankshaft, and is a motorcycle military engine.

A crankshaft 3 is horizontally supported within the crankcase 2 of the engine 1. On the rank case 2, a total of four cylinder blocks 4, two each on the left and right sides, are fixed and raised in a V-shape in the front and back, and the cylinder heads 5 are respectively attached thereto.

Pistons 6 are slidably inserted into the cylinder blocks 4, and are connected to the crankshaft 3 via connecting rods 7, which are connected to the crankshafts 3 and 8 provided at both ends of the crankshaft in the figure. is ACG, and 9 is a torque limiter.

The above cylinder head 5... has two camshafts 10... on each of the front two cylinders and the rear two cylinders via a holder 11, which are horizontally supported in the front and back parallel to the crankshaft. The example is an overhead cam shirt) (
0HC) type is shown, but the formula for the site valve type etc. is arbitrary. As is known, the camshafts 10 are equipped with cam portions 10a, which engage with valve rocker arms 13 that press the valve stems 12a of the intake/exhaust valves 12 to open and close them, as shown in FIG. ing. A drive gear 14 is formed on the circumference of the portion facing between the left and right cylinder blocks and the cylinder head at the axially intermediate portion of the crankshaft 3, and a reduction gear 15 is meshed and connected to this.
0 idle gear 16 which meshes and connects the idle gear 16 to
correspond to the front and rear cylinder units (two are provided spaced apart in the front and rear, therefore, the two idle gears with respect to the reduction gear 15 are meshed with each other so as to be symmetrical in the width direction with approximately half the tooth width. The idle gear 16 has a double structure with an inner and an outer part, and a damper spring 17 is interposed between the two parts. Furthermore, O reduction gear 1 is configured to absorb relaxation with this gear.
The support shaft 15a of the idle gear 16 is interposed at the joint between the left and right parts 2a and 2b of the crankcase 2, as shown in FIG.
It is an axially two-part type that fits in the axial direction, and each part faces the recess 4b of the upper part 4a of the cylinder block, and each part 18
a.

18b is tied to the divided members 19a and 19b of the holder 19, and the cylinder block and the holder (located between the cylinder block and cylinder head, so it faces the respective boundaries on the left and right, so the space between the divided parts of the cylinder head may be used. ) are fitted in the axial direction 1 and support the idle gear.

A camshaft drive gear 20, which is a final gear, is provided in the axially intermediate portion of each of the two camshafts 10 provided in the front and rear on the left and right cylinders, respectively. The idle gear 16 meshes with the drive gear 20 of the camshaft on the front and rear cylinders at approximately half of each tooth in the width direction, thereby driving the camshaft.

The details of the drive gear 20 are as shown in FIGS. 2 and 4. A flange portion 21 is provided in the middle of the camshaft 10, and an inner disk 22 of the gear 20 is fastened to this with bolts 23. An outer ring 24 having teeth 20a and an inner diameter larger than the outer diameter of the disk faces the outer circumference of the disk 22.
A damper rubber 25, which is a ring-shaped buffer member, is exposed between the outer diameter part 22a of the damper rubber 25, and the inner and outer diameter parts of the damper rubber 25 are joined to the inner and outer diameter parts of the ring and the disk by integral baking, etc. Note that the outer ring 24 and the inner disk 25 are partially coupled to each other by pins 26 at intervals of 180° in the embodiment.

Next, to explain the operation and effect, the power of the crankshaft 3 is transmitted via the gear 14, the reduction gear 15, and the idle gear 16 to the drive gear 20 fixed to the camshaft 10, and the camshaft is driven by the gear 20. 10 is rotationally driven. By the way, the collision of the cam portion 10a of the camshaft 10 with the rocker arm 13 causes the stem 12 to move downward against the spring force, opening the intake/exhaust valves 12, and this is done periodically.

At the time of such collision, a shock is transmitted to the camshaft 10, and this is transmitted to the gear drive system via the gear 20, causing wear of the gear drive systems 16, 15, and 14. However, in the present invention, the gear 20 is In this structure, a damping lever 25 is interposed between the camshaft and the toothed power transmission meshing part. Therefore, the impact of the camshaft 10 is relaxed and absorbed by the rubber 25, and the transmission of the impact to the teeth is substantially blocked at this portion. Therefore, it is possible to suppress the propagation of shock caused by the valve opening/closing operation of the camshaft to the gear drive system as much as possible, thereby protecting the drive system, suppressing wear, and improving durability. By providing a damper spring to the gear, the above effect is further improved.

Figures 5 and 6 show modified embodiments.

In this embodiment, a drive shaft 118 is provided in a direction perpendicular to the crankshaft 103, and the shaft 118 and the crankshaft 10
3 are meshed and connected by bevel gears 114 and 115, and a drive gear 120 provided at the shaft end of the camshaft 110 is a bevel gear, and the shaft (cranks 118) is meshed and connected to the bevel gear 116 of the crankshaft 118, and the power of the J shaft 103 is transferred to the camshaft 110. As if to communicate to
In this embodiment as well, the gear 120 is divided into an outer 124 and an inner 122, and a damper rubber 125 is interposed between them, and the same functions and effects as described above are obtained.

Although the embodiments have been described above, the present invention is not limited to a gear transmission mechanism, but can be used in a cheg or sprocket type camshaft drive system, and the above-mentioned buffer member may be interposed in the sprocket.

In summary, the present invention has the advantage of suppressing and preventing the transmission of periodic impacts of the camshaft to the camshaft drive system as much as possible, and improving the lifespan and durability of the camshaft drive system.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an explanatory longitudinal sectional side view of an internal combustion engine, FIG. 2 is an enlarged view of the main parts, and FIG.
4 is a sectional view taken along the line 4-4 in FIG. 1, FIG. 5 is an explanatory perspective view of a modified embodiment, and FIG. 6 is an enlarged sectional view of the drive gear section. In the drawings, 1 is an engine, 3 is a crankshaft, 10 is a camshaft, 14, 15, and 16 are power transmission means, and 20
25 is a driven member, and 25 is a buffer member. Figure 5 Figure 6

Claims (1)

[Claims] In a camshaft drive device consisting of a camshaft that controls intake and exhaust valves of an engine, and a driven member that drives the camshaft by a power transmission means that transmits rotation of the crankshaft to the camshaft, the driven member is provided with a buffer. A camshaft drive device characterized by being provided with a member.