JPH1181952A - Four-cycle engine and bracket for chain guide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine of a type in which a valve drive cam and other accessories are driven by a crankshaft, and the crankshaft and input shafts of the accessories are separated from each other by a large degree, without making the engine large-sized, complicated and heavyweight. SOLUTION: In a four-cycle engine 10 in which an oil pump 23 (accessory) and a cam shaft 22 are driven by power of a crankshaft 21, an input shaft 23a of the oil pump 23 is wound therearound with a transmission chain 35 which is in parallel with a transmission chain 34 wound on the cam shaft 22, and both chains are wound on the crankshaft 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a four-stroke engine intended to be mounted on a motorcycle or a personal watercraft, for example, in which a cam for driving a valve and an auxiliary machine such as an oil pump are connected to a crankshaft. And a chain guide bracket incorporated in the four-stroke engine.

[0002]

2. Description of the Related Art In a four-cycle engine, cams for opening and closing intake and exhaust valves are generally driven via a transmission chain (cam chain). That is, the sprocket is attached to both the crankshaft and the camshaft, and the transmission chain is wound around them. The rotation of the crankshaft when the engine is running is transmitted to the camshaft via its transmission chain or sprocket, and the cam rotates.

[0003] Auxiliary equipment such as an oil pump, a water pump, and a starter are attached to a four-cycle engine, and these are also driven by a crankshaft. As a power transmission means for them, conventionally, a gear (gear) has been used. Is often used. From the crankshaft to the input shaft of the accessory is connected only by one or more gears, or
A gear and a chain are used together so that the rotation of the crankshaft is first decelerated by a gear and then transmitted by a transmission chain. JP-A-59-46313 discloses an example in which only gears are used as power transmission means for an oil pump or the like.

[0004]

In the four-stroke engine, the driving of the accessories in the four-stroke engine through the gears from the crankshaft is good when the crankshaft and the input shaft of the accessories are close to each other. There are many disadvantages when the distance is quite large. For example, if power is to be transmitted by only one gear, a large radius corresponding to the distance between the two shafts (a radius that is equal to the distance between the shafts in total)
Therefore, it is necessary to combine two gears having the above-mentioned configuration, so that each gear occupies a large space in a range of 360 ° around each axis, and the engine becomes large. In order to avoid this, it is conceivable to combine small gears in multiple stages.However, it is not always easy to arrange the same number of shafts for supporting the gears so as not to contact the plurality of gears. Often complicated. Also, due to such circumstances, the weight of the engine is considerably increased regardless of whether a large gear is used or a large number of small gears are arranged. Such disadvantages in weight are not eliminated when gears and chains are used together.

The invention described in the claims has an engine in which a cam for driving a valve and other accessories are driven by a crankshaft, and an engine in which the crankshaft and the input shaft of the accessories are considerably separated from each other. It is an object of the present invention to make it possible to configure the apparatus without increasing the size, complexity, and weight as much as possible.

[0006]

The four-stroke engine described in claim 1 drives one or more of the four-stroke engines in a four-stroke engine that drives auxiliary equipment together with a cam by the power of a crankshaft. In order to achieve this, a transmission chain was wrapped around the accessory shaft, and the chain was parallelized with a transmission chain (so-called cam chain) wound around the camshaft to drive the cam, and was wrapped around the same crankshaft. Features. The term "auxiliary equipment" as used in the present application refers to equipment other than a cam, such as an oil pump, a water pump, or a starter, which is not directly related to the output but assists the smooth operation of the engine.
To make the chains parallel means to make the planes of the chains parallel to each other in a wound state.

[0007] In the four-stroke engine according to the first aspect, the power of the crankshaft is transmitted to any one of the auxiliary machines only by the chain. In order to transmit power using a chain, a sprocket is attached to the input shaft and crankshaft of the accessory and the chain is wrapped around the sprocket. The space occupied is smaller than that for transmitting, and the structure is simple and light. The space occupied is small because the sprockets on each shaft do not need to have a large diameter as in the case where power is transmitted by only one gear, and the chain itself connects only between the shafts and extends 360 ° around the shaft. Because it does not spread. The reason why the structure is simple is that there is no need to dispose a plurality of sprockets between shafts as in the case where power is transmitted by a plurality of gears. If the means for transmitting power to the auxiliary equipment can be made small and simple in this way, it is possible to reduce the weight of the means, and consequently the four-stroke engine including it. Note that a roller chain is generally used as a chain. For example, if a silent chain is used, the noise during operation can be reduced to a level equal to or lower than that when only gears are used.

The engine according to the first aspect of the present invention is advantageous in that the distance between the crankshaft and the input shaft of the auxiliary machine is large. In addition to the above, the present invention is also effective as an engine that requires auxiliary equipment to be located at a position distant from the crankshaft due to dimensional restrictions in the accommodation space. For example, small planing boats or automatic boats that place auxiliary equipment relatively farther to the side of the crankshaft than to the lower part close to the crankshaft due to the small space for mounting the engine and the need to lower the center of gravity In the case of a motorcycle engine or the like, the engine of the first aspect can exhibit advantages in the latter point.

According to a second aspect of the present invention, there is provided a four-cycle engine in which an auxiliary machine is driven together with a cam by the power of a crankshaft. Attach a chain guide (including a tensioner. The same shall apply hereinafter), and attach a plurality of chain guides of the chain guide and the chain guide of the transmission chain wound around the cam shaft for driving the cam to one. It is mounted via two common brackets.

[0010] According to this four-cycle engine,
First, in addition to using a transmission chain for driving the cam, the transmission chain is also used for driving other accessories. Therefore, several transmission chains are wound around this engine, and each chain has one or more chain guides (usually two on the tension side and the loose side). Means that two or more chain guides are arranged. In the engine according to the second aspect, a plurality of such chain guides are mounted via one common bracket. Since the number of brackets is smaller than the number of chain guides, the engine can be advantageously configured in terms of occupied space, weight, and ease of assembly. Also, if the number of brackets is small, the number of places to fix it to the inner wall of the engine is also small, but the fact that the number of brackets and their fixed parts is small inside the engine where many moving parts are densely packed means that The arrangement of various parts in the engine can be greatly simplified, and unnecessary weight can be saved.
Therefore, the engine according to the second aspect is also configured to be small, simple, and lightweight, and it is easy to reduce the manufacturing cost.

According to a third aspect of the present invention, in the engine of the second aspect, the power transmission chain for driving the accessory is wound around the same crankshaft in parallel with the power transmission chain for driving the cam. The chain guide (for example, one of them) of the drive chain for driving the machine and the chain guide (for example, one of them) of the drive chain for driving the cam are connected via one common bracket. It is characterized by being attached.

The engine according to the third aspect has the features of each engine described in the first and second aspects in structure. Therefore, it is easier to reduce the size, simplification and weight, and furthermore to reduce the manufacturing cost, and it is still more suitable as an engine or the like which requires the auxiliary equipment to be located at a position away from the crankshaft due to the limitation of the accommodation space. There is such an advantage.

In the case of this engine, the above-mentioned common bracket is configured to be small and simple. Since the transmission chain for driving the auxiliary equipment is wound around the same crankshaft in parallel with the transmission chain for driving the cam, the two chains approach each other at least near the crankshaft, and therefore a chain guide attached to those chains Is also close to the crankshaft. Common brackets for mounting closely spaced chain guides are naturally smaller and simpler than those for distant chain guides,
Further promote downsizing of engines.

The chain guide bracket according to the fourth aspect is incorporated in the four-stroke engine according to the third aspect, and two chain guides are attached thereto (therefore, one of the chain guides is driven by an auxiliary machine). As a bracket (a bracket common to the two chain guides), which is attached to the transmission chain for the other, and the other is attached to the transmission chain for driving the cam.
It is characterized in that it includes a portion fixed to the engine, a portion to which one of the chain guides is integrally attached, and a portion to which the other chain guide is swingably attached.

This bracket is fixed to the engine by integrally attaching one of the chain guides and swingably attaching the other chain guide. Claim 3
Since the above-mentioned common bracket is incorporated in the engine described above, it is small and simple, and contributes to downsizing and weight reduction of the engine.

This bracket, to which the two chain guides are attached and which is fixed to the engine as described above, further has a function of maintaining the tension of the chains together with a guide function for each of the transmission chains for driving the accessory and the cam. Can be demonstrated. A chain guide integrally attached to the bracket appropriately guides the tight side of one of the above transmission chains along the tension side, and the other chain guide swingably attached to the bracket is the other. Is attached to the slack side of the transmission chain and swings following the slack, thereby performing a guide function and always giving the chain an appropriate tension. The fact that the integral (fixed) chain guide and the oscillating chain guide mounted on the bracket can function in this way is generally the case in the engine according to claim 3 in which the transmission chain has a tight side and one of the transmission chains. This is because the other side of the transmission chain is very close to the loose side of the transmission chain. That is, when each of the transmission chains for driving the accessory and the driving cam are wound on the same crankshaft from different directions (that is, from the accessory input shaft and the camshaft in different directions), for example, FIG. As shown, on one side (upper left of the figure) of the crankshaft 21 (the rotation direction is indicated by an arrow), the tight side of the accessory drive chain 35 and the loose side of the cam drive chain 34 are close to each other, and pass each other. On the other side, the loose side of the accessory drive chain 35 and the tight side of the cam drive chain 34 approach each other. As the bracket 47 in FIG. 3 is disposed at a position where the tight side of one chain and the loose side of the other chain are close to each other, the bracket of claim 4 can be used to move the chain through two chain guides. The guiding function and the tension maintaining function can be exhibited.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a front view showing a part of the four-stroke engine 10 in a cross-sectional view, and is a II cross-sectional view in FIG. FIG. 2 is a longitudinal sectional view of the engine 10, and is a II-II sectional view in FIG. 1, and FIG.
3 is a detailed view showing the vicinity of the crankshaft 21, and FIG. 4 is a sectional view taken along the line IV-IV in FIG. FIG. 5 is an overall side view showing a part of the personal watercraft 1 on which the engine 10 is mounted.

A personal watercraft 1 shown in FIG. 5 is a vehicle that slides on water near a shore or a lake shore.
Several people can board. The water jet pump is propelled by a water jet that is pressurized and jetted by an impeller 7 of a water jet pump at the lower rear, and can slide on the water surface. The impeller 7 is driven by an engine 10, and the engine 10 is mounted in an engine room 8 substantially at the center in the longitudinal direction of the hull. The output of the engine 10 is transmitted to an impeller shaft 9 via an elastic joint (not shown), and the impeller shaft 9 rotates the impeller 7. In the figure, reference numeral 15 denotes an intake passage of the engine 10, and reference numeral 16 denotes an exhaust passage.

The engine 10 is a four-cylinder four-stroke engine. As shown in FIG. 2, a piston 25 is provided inside the cylinder head 11, the cylinder 12, the crankcase 13, and the like.
And the like are arranged in four sets. Each of the pistons 25 is connected to the crankshaft 21, and the crankshaft 21
Are connected to the impeller shaft 9 (FIG. 5) as described above. The rotation direction of the crankshaft 21 is clockwise in FIGS. 1 and 3.

As shown in FIG. 1, inside the cylinder head 11,
Two camshafts 22 (cam body not shown) for driving a valve operating mechanism (not shown) are provided in parallel, and for transmitting power to them, the camshaft 22 and the crankshaft 21 are provided.
A transmission chain 34 (a silent chain in form, sometimes called a cam chain in terms of function) is wound between the transmission chain 34 and the transmission chain 34. Reference numerals 31A and 32 denote sprockets attached to the crankshaft 21 and the camshaft 22 for transmitting power.

Reference numeral 24 in FIG. 1 denotes a starter motor which is one of the accessories in the engine 10. When the engine 10 is started, a battery (not shown)
By rotating the motor 24, the crankshaft 21 is rotated through two gears, a small gear 24a and a large gear 24b and a small gear 24c and a large gear 24d. Large gear 2
4b and the small gear 24c are coaxial. After the engine 10 starts, the motor 24 is not driven.
A one-way clutch (reference numeral 24x in FIG. 2) is built between the gear 24d and the crankshaft 21. In addition,
Since the motor 24 is an electric device and preferably has a waterproof property, the motor 24 is mounted at a relatively high position so that even if some water enters the engine room 8, it is not immersed therein.

The engine 10 employs a so-called dry sump lubrication system in which an oil tank 14 for lubricating oil is provided on the side of the cylinder block 12 and the crankcase 13. The dry sump type is used in order to eliminate the necessity of providing an oil pan at the bottom of the crankcase 13, to suppress the height of the engine 10, and to reduce the size and the center of gravity of the personal watercraft 1. Since the dry sump type is used, there is no reduction in output due to the contact of the rotating body such as the crankshaft 21 with the lubricating oil surface.
There are many advantages that are suitable for small personal watercraft, such as that the lubricating oil is not agitated by scraping inside, so that the rise in oil temperature can be suppressed. Because of the dry sump type, this engine 10
In the above, only a simple passage (not shown) as an oil receiver is formed at the bottom of the crankcase 13, and the lubricating oil supplied to each part in the engine 10 passes through the passage to an oil tank. 14 and stored there. Then, the lubricating oil is supplied to each part in the engine 10 such as a valve mechanism (not shown), the transmission chain 34, and a main bearing (not shown) of the crankshaft 21.

The lubricating oil is sent from the bottom of the crankcase 13 to the oil tank 14 and the oil tank 1
The supply of lubricating oil from 4 to each part in the engine 10
This is an operation of the oil pump 23 which is one of the accessories of the engine 10. Oil pump 2 for compactness
3 is an oil tank 1 from the bottom of the crankcase.
Scavenging pump (not shown) that sends lubricating oil to 4.
And a feed pump (not shown) for pumping the lubricating oil from the oil tank 14 to each section.
3a is used, and both casings are connected.

In the engine 10, the oil pump 23
Is driven by a transmission chain (silent chain) 35 wound around the input shaft 23a and the crankshaft 21. That is, the sprocket 31B is mounted on the crankshaft 21 adjacent to the above-described sprocket 31A (see FIG. 2), and the sprocket 33 is mounted on one input shaft 23a as well, in a plane parallel to the above-mentioned chain 34. Power is transmitted by bridging the chain 35 between the sprockets 31B and 33.

The power transmission between the crankshaft 21 and the input shaft 23a is performed by the chain 35 because the shafts 21 and 23a are located far apart from each other as shown in FIG. Is about 100 mm), which makes the configuration simpler than using gears. That is, between the crankshaft 21 and the input shaft 23a having such a long distance, the power transmission structure of the chain 35 and the sprockets 31B and 33 is smaller and lighter than the structure of the gears and the like. The reason that there is such a distance between the shafts 21 and 23a is as follows: a) As with the dry sump type, the engine 10
The oil pump 23 could not be located directly below the crankshaft 21 for the purpose of suppressing the height of the crankshaft 21. b) As described above, the starter motor 24 Since the space between the gear and the crankshaft 21 is occupied by the two-stage gears 24a to 24d, it is necessary to arrange the oil pump 23 to avoid contact with them. is there. That is, the position of the oil pump 23 and its input shaft 23a is changed to the position of the crankshaft 21 on the basis of the circumstances peculiar to the personal watercraft 1 that the engine 10 is made small and has a low center of gravity and the electric components are arranged away from the bottom of the boat. They are far away from. The power transmission from the starter motor 24 to the crankshaft 21 is not performed by the transmission chain because the reduction ratio between the motor 24 and the crankshaft 21 is extremely large. This is because a simple configuration of connecting the sprockets with a chain cannot be taken.

A transmission chain 34 wound around the cam shaft 22
As shown in FIG. 1, a fixed type chain guide 41 is attached to the tension side (right side in the figure), and a swing type chain guide 42 is attached to the loose side (left side). In contact with the outer surface. A chain tensioner assembly 43 including a ratchet mechanism is engaged with the upper portion of the swing type chain guide 42. If the chain 34 tends to become loose due to long-term use, the chain tensioner assembly is used. 43 pushes the chain guide 42 inward to prevent a decrease in tension.

Similarly, a fixed type chain guide 44 is attached to the tension side (upper side in the figure) of the transmission chain 35 wound around the input shaft 23a of the oil pump 23, and the transmission side 35 is loosened (lower side). Swing type chain guide 45
Are attached to the outer surfaces of the chains 35 respectively. A chain tensioner assembly 46 is engaged with the lower surface of the swing type chain guide 45 to prevent the chain 35 from loosening. The assembly 46 is, as shown in FIG. 3, a cap 46c attached to the tip of a compression coil spring 46b placed in a cylinder 46a, and a chain guide 45 swingably mounted on a pin 45a as a fulcrum. The cap 46c is pushed upward by the action of.

In the engine 10, as shown in FIG. 3, a chain guide 42 for the transmission chain 34 and a chain guide 44 for the transmission chain 35
It is mounted on one common bracket 47. The bracket 47 is made of sheet metal and is fixed on the wall surface of the crankcase 13 by three bolts 47a as shown in FIG. A rubber (or resin) chain guide 44 is integrated with the bracket 47 on one side, and a bracket piece 47b is fixed to the other side using two of the bolts 47a. The pin 42c is supported between the bracket 47 and the piece 47b, and the chain guide 42 is attached so as to be swingable via the pin 42c. The chain guide 42 is formed by attaching a rubber (or resin) main body 42a having a guide groove for the chain 34 on a metal base 42b.

The two transmission chains 34 and 35 are wound around the crankshaft 21 at a close position as shown in FIG.
At the side narrowed at 4.35, the loose side of the chain 34 and the tight side of the chain 35 are extremely close to each other on the crankshaft 21 (upper left side in FIG. 3). Therefore, even though the chain guides 42 and 44 are compactly mounted on one common bracket 47, it is possible to appropriately prevent the chain 34 from loosening and guide the chain 35.

Although one of the embodiments has been described above, it goes without saying that the present invention can be carried out in other forms. For example, when the rotation direction of the crankshaft 21 is opposite to the arrow in FIG.
(One of the chain guides is integrally mounted and the other is swingably mounted.) A bracket can be used for smooth functioning. In this case, since the tension side of the chain 34 and the loose side of the chain 35 are close to each other, the chain 34 is guided by a fixed chain guide, and the chain 35 is guided by an oscillating chain guide.
This is because it is possible to prevent loosening. Further, the bracket having the same configuration may be arranged on the opposite side (the lower right side in FIG. 3 when viewed from the crankshaft 21) of the bracket 47 in FIG. 3 to perform the same function. Can be. This is because the tight side of one chain and the loose side of the other chain are also close to that side.

In addition, the above-described configuration may be adopted in which the power of the crankshaft is transmitted to another auxiliary machine by a transmission chain instead of or together with the oil pump 23. It is also possible to configure the four-stroke engine of the invention as an engine other than the personal watercraft. In addition, as an application of the invention, it is also possible to replace a chain for an auxiliary machine with a timing belt or the like.
In some cases it is possible.

[0032]

The four-stroke engine according to the first aspect has the following effects. 1) Since the power of the crankshaft is transmitted to one or more of the auxiliary machines only by the transmission chain, the power transmission means is relatively small and simple when the distance between the shafts is large to some extent. Further, it can be configured to be lightweight, and the engine can be made compact and the manufacturing cost can be reduced. The noise is also low.

2) A large engine in which the crankshaft is separated from the input shaft of the auxiliary machine, or an engine in which the auxiliary machine must be located at a position away from the crankshaft due to dimensional restrictions in the accommodation space, etc. (For example, engines for small personal watercraft and motorcycles), the advantages of 1) above are particularly remarkable.

In the four-stroke engine according to the second aspect of the present invention, 1) since two or more of the plurality of chain guides arranged inside are mounted via one common bracket, the number of the brackets is reduced. This is advantageous in terms of weight and ease of assembly.

2) Also, since the number of brackets and their fixing points is reduced inside the engine where a large number of parts are densely arranged, the arrangement of the internal parts can be extremely simplified, and the size and weight of the engine can be reduced. To contribute.

The four-cycle engine according to the third aspect further has the effects of the respective engines according to the first and second aspects, such as 3) downsizing, simplification, weight reduction, and cost reduction.

4) The common bracket is particularly small and simple in relation to the arrangement of the transmission chain and the chain guide, so that the engine is further downsized.

The bracket for a chain guide according to the fourth aspect of the present invention is as follows: 1) Since it is the above-mentioned common bracket incorporated in the engine of the third aspect, it is configured to be small and simple, contributing to downsizing and weight reduction of the engine. I do.

2) The chain guide attached to the bracket has a guiding function and a chain tension maintaining function for each of the transmission chains for driving the accessory and the cam. Thus, the bracket, while compact, performs the multiple functions required to operate the engine smoothly.

[Brief description of the drawings]

FIG. 1 is a front view showing a part of a four-stroke engine 10 in a cross section to show an embodiment of the present invention, and is a view taken on line II in FIG.

FIG. 2 is a longitudinal sectional view of the engine 10 of FIG.
FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a detailed view showing the vicinity of a crankshaft 21 in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3 and is a detailed view of a bracket 47.

FIG. 5 is an overall side view of the personal watercraft 1 equipped with the engine 10 shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Small personal watercraft 10 4 cycle engine 21 Crankshaft 22 Camshaft 23 Oil pump (Auxiliary equipment) 23a Input shaft 34/35 Transmission chain 41/42/44/45 Chain guide 47 Bracket

Claims (4)

[Claims] In a four-stroke engine that drives an accessory together with a cam by the power of a crankshaft, a transmission chain is wound around a shaft of the accessory to drive the accessory, and the chain is attached to a camshaft to drive the cam. A four-stroke engine characterized by being wound around the same crankshaft in parallel with the wound transmission chain. 2. In a four-stroke engine in which an auxiliary machine is driven together with a cam by the power of a crankshaft, a transmission chain is wound around an auxiliary machine shaft for driving the auxiliary machine, and a chain guide is attached to the chain. A four-stroke engine, wherein a plurality of chain guides of a guide and a chain guide of a transmission chain wound around a cam shaft for driving a cam are mounted via a common bracket. 3. A transmission chain for driving an accessory is wound around the same crankshaft in parallel with a transmission chain for driving a cam, and a chain guide of the transmission chain for driving the accessory and a cam of the cam are provided. The chain guide of the drive chain for driving
The four-stroke engine according to claim 2, wherein the engine is mounted via one common bracket. 4. A bracket which is incorporated in the four-stroke engine according to claim 3 and to which two chain guides are attached, a portion fixed to the engine, a portion to which one chain guide is integrally attached, and a A chain guide bracket including a part for swingably attaching a chain guide.