JPS6024911Y2 - Engine auxiliary drive device - Google Patents

Description

[Detailed description of the invention] The present invention relates to an engine accessory drive device that can be applied, for example, to drive an oil pump attached to the side of a two-stroke engine. The purpose is to provide a compact structure that can obtain a large reduction ratio.

Conventionally, when a pump case is fixed to the crankcase of a two-stroke engine and the pump inside the pump case is driven by the crankshaft, a small diameter gear (or sprocket) fixed on the crankshaft and a small diameter gear (or sprocket) fixed on the pump shaft are used. Large-diameter gears (or sprockets) were connected directly or via intermediate gears (or chains), and a worm gear for reduction was required on the pump shaft.

As a result, parts of the reduction mechanism such as large-diameter gears and chain cases were bulky, and it was difficult to obtain a large reduction ratio.

Reduction worm gears require high-precision machining, which inevitably increases manufacturing costs.

This invention uses an eccentric cam on the crankshaft and a rack supported in the bearing hole of the crankcase for reciprocation only, converting the rotation of the crankshaft into a reciprocating motion of the rack with a small stroke, and employs a one-way clutch to move the rack. This system converts the reciprocating motion into a gentle unidirectional rotation of the pump shaft to avoid the above-mentioned conventional problems. An eccentric cam is fixed to the crankshaft, a ring is fitted to the outer surface of the cylinder, and the crank is attached to the ring. The racks are connected via pins parallel to the shafts, and the racks are supported reciprocally only in bearing holes perpendicular to the crankshaft of the crankcase, exposing the teeth of the racks in the auxiliary equipment case, and connecting the racks to the auxiliary equipment. It is characterized in that it engages with a gear attached to the shaft of the auxiliary machine within the case via a one-way clutch, and the shaft of the auxiliary machine is rotated in one direction by the reciprocating movement of the rack.

FIG. 1 is a plan view of the mating surfaces of a lower crankcase 1 when the present invention is adopted for driving an oil pump of a two-stroke engine, and FIG. 2 is a sectional view taken along the line 1--m in FIG. 1.

1 and 2, a crankshaft 3 is supported by a crankcase 1 via a bearing 2, and an eccentric cam 4 is press-fitted onto the crankshaft 3.

A ring 6 is slidably fitted onto the cylindrical outer surface 5 of the cam 4.

The ring 6 is provided with a notch 7 (Fig. 2) extending in the circumferential direction at the center of the width of the cylindrical outer surface 5, and two flanges 8 on both sides of the notch 7 are provided with a notch 7 parallel to the crankshaft 3. Na pin 9
The racks 10 are connected via.

As shown in FIG. 1, the ring 6 is positioned at the position shown between the two bearings 2 by holders 11 and 12 on both sides.

The rack 10 is slidably fitted and supported in a bearing hole 13 formed in the main body of the crankcase 1, and the teeth 10a are exposed in a gear chamber 15 within a gear case 14 and mesh with a gear 16 there.

The bearing hole 13 has a centerline on a plane perpendicular to the crankshaft 3 as shown in FIGS. 1 and 2.

The gear 16 is attached to the pump shaft 18 via a one-way clutch 17.

19 is a pump case bolted to the gear case 14 portion.

In FIG. 3, which shows the cross-section taken along the line ■-■ in FIG. 2, 21 is a cam for adjusting the discharge amount, which is connected to the throttle lever.

22 is a plunger that is reciprocated by a cam mechanism (not shown) as the pump shaft 18 rotates, 23 is a distributor, 24 is a return spring, and 25 is a suction port.

Next, the operation will be explained.

When the crankshaft 3 rotates, the integrated eccentric cam 4 also rotates,
The center 0° of the cylindrical outer surface 5 revolves around the center 01 of the crankshaft 3 on the circumference with the eccentricity 1 as the radius, so the center of the ring 6 also moves according to the center 02 of the cylindrical outer surface 5, and the ring 6 and Since the rack 10 connected by the pin 9 is supported in the bearing hole 13 of the crankcase, it reciprocates within the bearing hole 13 with a stroke of 21.

The gears 16 repeatedly rotate in opposite directions within a certain angle range in response to the reciprocating movement of the rack 10 on a straight line.
The pump shaft 18 is driven in one direction of the arrow through the one-way clutch 17.

When the pump shaft 18 rotates in one direction, the plunger 22 (Fig. 3) reciprocates, and the lubricating oil sucked in from the suction port 25 is pressurized and supplied from the discharge port (not shown) to the target part that requires lubrication. be done.

The present invention can be embodied as described above, and according to the present invention, by appropriately selecting the eccentricity 1 of the eccentric cam 4, the stroke (21) of the reciprocating motion of the rack 10 can be made sufficiently small. Since the directional clutch 1 is employed, only one side of the reciprocating motion of the rack 10 is used to drive the pump shaft 18, and a large reduction ratio can be obtained.

Adopting the eccentric cam 4 eliminates the need for expensive reduction mechanisms such as small-diameter gears and large-diameter gears, and also eliminates the need for reduction worm gears that require advanced processing, which not only greatly simplifies the structure, but also occupies less space. This makes the entire device lighter and smaller.

Note that since the bearing hole 13 of the rack 10 is provided in the crankcase 1, the length of the bearing hole 13 can be increased, making it easier to stably support the rack 10.

In the present invention, the rack 10 is supported in a bearing hole 13 of the crankcase 1 that is orthogonal to the crankshaft 3 so that it can move only reciprocally, and there is a risk that it will swing or tilt in a plane perpendicular to the crankshaft 3 during operation. Therefore, the teeth 1 of the rack 10
0a can be directly engaged with the gear 16 for driving auxiliary equipment.

Moreover, since the rack 10 is connected to the ring 6 via one pin 9, there is no need to provide a swingable connecting rod between the rack 10 and the ring 6, and the rotational movement of the crankshaft 3 can be moved back and forth. The number of component parts of the power transmission mechanism is minimized when changing the movement to rotational movement of the pump shaft 18 again, making it compact and inexpensive.

Rotation of the rack 10 is prevented by the pin 9 and the ring 6,
Since the rotation of the ring 6 is blocked by the rack 10 via the pin 9, the posture of the rack 10 and the ring 6 is always stable, and the engagement part between the rack 10 and the gear 16 and the engagement part between the ring 6 and the eccentric cam 4 are This has the advantage that unreasonable small conflicts do not occur, smooth operation is achieved, and durability is increased.

In addition, by making the rack 10 longer, the pump shaft 18 can be moved far away from the crankshaft 3, allowing auxiliary equipment such as a pump to be placed on the road at an optimal position from the crankshaft 3, increasing the degree of freedom in design. .

In addition, if a notch 7 is provided in the ring 6 and the rack 10 is connected to the two flanges 8 via a pin 9, the structure of the connected part will be strong, and if the holder 11°12 is used, the ring 6 will be This has the advantage of eliminating the risk of deviation in direction and stabilizing the operation.

In addition to the oil pump, the auxiliary equipment used when embodying the present invention may include a speedometer, a tachometer, a magneto contact breaker, etc.

[Brief explanation of the drawing]

Figure 1 is a plan view of the crankcase mating surface, and Figure 2 is a plan view of the crankcase mating surface.
FIG. 3 is a partial cross-sectional view taken along the line ■--■ in FIG. 2. 3... Crankshaft, 4... Eccentric cam,
5... Cylindrical outer surface, 6... Ring, 9...
...Zen, 10...Rack, 1...
・Crankcase, 13...Bearing hole, 19...
...Pump case (example of auxiliary equipment case), 18...
...Pump shaft, 17...One-way clutch, 1
6...Gear.

Claims (1)

[Scope of utility model registration request] An eccentric cam is fixed to the crankshaft, a ring is fitted to the outer surface of the cylinder, a rack is connected to the ring via a pin parallel to the crankshaft, and the rack is connected to a bearing hole perpendicular to the crankshaft of the crankcase. The teeth of the rack are supported in a reciprocating manner only and exposed inside the auxiliary equipment case, and the rack is engaged with a gear attached via a one-way clutch on the shaft of the auxiliary equipment in the auxiliary equipment case. An accessory drive device for an engine, characterized in that the shaft of the accessory is rotated in one direction by reciprocating motion.