JPH0814061A - Scotch yoke type engine - Google Patents

Abstract

PURPOSE:To arrange a crank shaft between the two central lines of first and second cylinders to form an engine in a compact manner by arranging cylinders in parallel to each other as a yoke is used in common. CONSTITUTION:First and second cylinders 1 and 2 are arranged in the same direction paralleling the movement directions of first and second pistons 7 and 10 at each stroke of an engine. The axis of a crank shaft 16 is arranged in a direction extending vertically to a plane containing the central lines of the first and second cylinders 1 and 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a slider crank chain arrangement for an engine having at least two cylinders.

[0002]

2. Description of the Related Art Generally, an engine used in an automobile or the like has a mechanism for converting reciprocating motion of a piston obtained by utilizing combustion pressure of gasoline or light oil into rotary motion. Conventionally, this conversion mechanism generally converts the reciprocating motion of the piston into a rotary motion by the oscillating motion of the connecting rod that connects the piston and the crank pin of the crank shaft. However, this swinging movement causes interference between the connecting rod and the cylinder bore wall skirt portion, so the distance between the piston and the crankshaft must be long. On the other hand, the Scotch-yoke type engine is provided with a slider mechanism that can freely reciprocate in a direction other than the reciprocating direction of the piston and connects the connecting rod (hereinafter referred to as the yoke) and the crankshaft to each other. Can only reciprocate. As a result, the above interference is eliminated, and the distance between the crankshaft and the piston can be shortened.

An example of this Scotch yoke type engine is disclosed in Japanese Patent Laid-Open No. 58-210326. The Scotch-yoke engine shown here is a horizontally opposed Scotch-yoke engine in which two cylinders, a first cylinder and a second cylinder, face each other horizontally about a crankshaft.
The yoke shares a slider used for the first cylinder and the second cylinder. Due to this commonality, the length in the crankshaft direction is further shortened compared to the conventional horizontally opposed engine.

[0004]

However, in such a horizontally opposed type Scotch yoke type engine, since the cylinder block portions occupying a large space are arranged horizontally facing each other and are dispersed first and second, There is a problem that the integration as the main body is poor. The present invention
In a Scotch yoke type engine, it is an object to make the engine compact by disposing the cylinders in parallel while commonizing the yokes so that the crankshaft is disposed between the central axis lines of the first and second cylinders.

[0005]

The present invention for achieving the above object has the following constitution. According to the present invention described in claim 1, first and second cylinders, and a first piston and a second piston that are reciprocally provided in the first cylinder and the second cylinder, respectively. ,
In a Scotch-yoke type engine provided with a yoke for transmitting the reciprocating motions of the first and second pistons to a crankpin of a crankshaft, the movement directions of the first piston and the second piston are parallel in each stroke of the engine. The first and second cylinders are arranged so as to be oriented in the same direction, and the axis of the crankshaft is arranged in a direction perpendicular to a plane including the central axes of the first and second cylinders. Further, according to the present invention described in claim 2, in the Scotch yoke type engine described in claim 1, the first piston pin connecting the first piston and the yoke, the second piston and the yoke, And a second piston pin for connecting the two are displaced from each other in the reciprocating direction.
According to the present invention as set forth in claim 3, in the Scotch yoke type engine as set forth in claim 1, immediately after the first or second cylinder is in a combustion state, the crank pin is the first cylinder. The shaft center of the crankshaft is biased so as to be located between the center axis of the second cylinder and the center axis of the second cylinder.

[0006]

According to the present invention as set forth in claim 1, the first and second cylinders are arranged such that the movement directions of the first piston and the second piston in each stroke of the engine are parallel and in the same direction. Since the axis of the crankshaft is arranged in a direction perpendicular to the plane containing the central axes of the first and second cylinders, the engine width should remain small and the engine width should be small and compact. It is possible to increase the concentration of mass. Further, in the present invention as set forth in claim 2, the first piston pin connecting the first piston and the yoke and the second piston pin connecting the second piston and the yoke are displaced in the reciprocating direction. It is arranged. That is, during mounting or when the engine is cold, the yoke is stable in a state in which it is slightly inclined with respect to the center axes of both the first cylinder and the second cylinder. afterwards,
When the engine continues to operate, the first and second cylinders, cylinder blocks, and pistons near the combustion chamber undergo thermal expansion due to combustion heat, and the distance between the first and second cylinders increases. On the other hand, since the yoke is separated from the combustion chamber, thermal expansion due to heat is relatively small, and a difference in thermal expansion occurs between the yoke and the first and second cylinders. Even if this difference in thermal expansion occurs, the difference in thermal expansion can be absorbed only by reducing the inclination of the yoke, and the stress and strain inside the engine can be reduced. Further, the piston side force in which the first and second pistons press the cylinder walls of the first and second cylinders, respectively, increases as the pressure in the combustion chamber increases,
Further, the straight line connecting the crank pin and the piston pin becomes smaller as it gets closer to the reciprocating direction. Further, if the piston side force becomes extremely large, the smoothness of the sliding of the piston is impaired, so there is a demand to keep the maximum value of the piston side force low. Therefore, in the present invention as set forth in claim 3, immediately after the combustion state in which the piston side force is likely to be maximized, the crank pin is provided between the center axis of the first cylinder and the center axis of the second cylinder. The maximum piston side force of the first and second cylinders can be made uniform by displacing the axis of the crankshaft so as to be located at. That is, the maximum value of the piston side force can be kept low for the entire engine. Further, the uneven stress distribution of the yoke, which originally occurs when the first cylinder is in the combustion state and when the second cylinder is in the combustion state, can be significantly reduced.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view from above the cylinder head of a 4-cycle 4-cylinder Scotch yoke type engine of the embodiment. In the Scotch yoke engine of this embodiment, the first cylinder 1, the second cylinder 2, the third cylinder 3, and the fourth cylinder 4 are arranged in a square type as shown in FIG. As shown in FIG. 1, an intake manifold 5 and an exhaust manifold 6 are attached to an intake valve 8 and an exhaust valve 9 respectively provided in the cylinder heads of the four cylinders.

FIG. 2 is a side cross-sectional view of the Scotch yoke type engine of this embodiment, showing a cross section taken along the line XX 'in FIG. Above the cylinder head 21, a camshaft 2 that drives the intake valve 8 and the exhaust valve 9 is provided.
2 is arranged, and an oil pan 2 is provided below the crankshaft 16.
3 is provided. A water jacket 24 is provided on the cylinder head 21 for cooling, and cooling water is circulated by a water pump (not shown). Piston 7
And 10 are provided with a piston ring 25 and at the bottom of the cylinders 1 and 2 there is a cylinder skirt 26.

FIG. 3 is a front sectional view best showing the characteristics of the Scotch yoke type engine of the present embodiment, and shows a YY 'section in FIG. The central axes of the first cylinder 1 and the second cylinder 2 are arranged in parallel, and the crankshaft 1
6 is arranged in a direction perpendicular to a plane including both central axes and between the central axes of both the first cylinder 1 and the second cylinder 2. The first piston 7 provided in the first cylinder 1 and the second piston 10 provided in the second cylinder 2 have a first piston pin 11 and a second piston 10 arranged parallel to the axis of the crankshaft 16. Two piston pins 12 are attached to each yoke 13. The two pistons 7 and 10 arranged in a plane orthogonal to the axis of the crankshaft 16 are respectively the piston pins 1
The yoke 13 is rotatably attached to the yoke 13. An elongated hole 15 that slidably accommodates the slider 14 is provided below the yoke 13. In the Scotch yoke type engine of the present embodiment having the above-mentioned configuration, the intake / exhaust valve timing is set so that the second cylinder 2 is in the intake stroke when the first cylinder 1 is in the combustion stroke. The third cylinder 4 and the fourth cylinder 4, which are driven 180 degrees out of phase with each other in the angle, respectively compress and
Since the intake / exhaust valve timing is set so that the exhaust stroke is performed, the engine as a whole has four cycles and four cylinders.
Equally spaced combustion every 80 ° is achieved.

Since one set of the first cylinder 1 and the second cylinder 2 and one set of the third cylinder 3 and the fourth cylinder 4 have the same construction, the first set will be described below in order to explain the features of this engine. Only one cylinder 1 and the second cylinder 2 will be described. Since the engine is operated according to the 4-stroke cycle, the first piston 7 and the second piston 10
The intake valve 8 and the exhaust valve 9 are operated in conjunction with the reciprocating motion of FIG. 3 is a cross-sectional view of the Scotch yoke type engine of the present embodiment when the crank angle is 0 ° after top dead center. The compression stroke is completed in the first cylinder 1 and the exhaust stroke is completed in the second cylinder 2. It shows that it did. FIG.
FIG. 4 is a cross-sectional view when the crank angle is 90 ° after top dead center, the first cylinder 1 shows an expansion stroke, and the second cylinder 2 shows an intake stroke. FIG. 5 is a cross-sectional view at 180 ° after top dead center, in which the expansion stroke of the first cylinder 1 is completed and the intake stroke of the second cylinder 2 is completed. FIG. 6 is a cross-sectional view at 270 ° after top dead center, in which the first cylinder 1 is in the exhaust stroke and the second cylinder 2 is in the compression stroke. From these figures, the position of the slider 14 was at the center of the elongated hole 15 when the angle was 0 ° after the top dead center.
It has moved to one end of 5. Then, as the crank angle changes from 180 ° to 270 ° after top dead center, the slider 14
Is moving through the long hole 15 and the slider 1 at 90 ° after top dead center
It has moved to the other end opposite to the position of 4. In this way, as the crankshaft 16 rotates, the pistons 1 and 2 reciprocate in the cylinder, while the slider 14 reciprocates in the elongated hole 15 in a direction perpendicular to the reciprocating motion of the pistons 1 and 2. Exercise. In this way, the piston 1,
The reciprocating motion of 2 will be converted into the rotary motion of the crankshaft 16. Further, the slider 14 is the crankshaft 1
Along with the rotation of 6, the reciprocating lubricating motion is performed in the elongated hole 15 in the longitudinal direction of the elongated hole 15. In this way, by arranging the four cylinders in a square shape, the clearance between the cylinders can be eliminated, the crankshaft direction can be shortened, the engine can be made compact, and the freedom of the layout of the engine center of gravity that determines the dynamic performance of the vehicle can be obtained. growing. In addition, since the cylinder head can be made compact, it is low cost and lightweight, and because the entire engine is compact, it becomes a highly rigid engine unit, and the engine mount when the engine is mounted can be highly rigidly supported. It is also useful for reducing vibration from.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIG. In FIG. 7, the yoke 13 is 2
Although the piston pins 11 and 12 of the book and the crank pin 20 are supported in a static state at a total of three points, the yoke 13 is slightly separated from the piston pin hole centers 11 ′ and 12 ′ at the upper end of the yoke 13 by the cylinder 1 It is manufactured by setting the distance larger than the distance between both center lines of 2 (actually within several tens of micrometers), and this yoke is assembled to the engine. Therefore, when the engine is installed and when the engine is cold, a in FIG.
As described above, the piston 7 and the piston 10 are vertically displaced slightly by the displacement width d, and the yoke 13 is stable in a state of being slightly inclined with respect to the cylinder center axes of the first cylinder 1 and the second cylinder 2. On the other hand, during the operation after the engine is warmed up, the distance between the center axes of the first cylinder 1 and the second cylinder 2 increases due to thermal expansion and the like, and the distance between the piston pins 11 and 12 is relatively reduced. In this case, the preset inclination of the yoke 13 is automatically corrected in the direction approaching 0 ° as shown in FIG. 7B. Therefore, the stress and strain generated inside the engine due to the dimensional error such as the difference in thermal expansion due to the operation can be absorbed by the inclination of the yoke, and the smooth operation can be always performed regardless of whether it is cold or after warming up.

Next, returning to FIG. 3, an embodiment of the invention described in claim 3 will be described. Immediately after the combustion state in the first or second cylinder, the crankpin 20 is positioned so that the crankpin 20 is located between the center axis of the first cylinder 1 and the center axis of the second cylinder 2. Is offset by a predetermined amount e. FIG. 8 compares the Scotch yoke engine in which the crankshaft is offset by the offset amount e and the Scotch yoke engine in which the crankshaft is not offset by the piston side force amount. From this, when there is no offset of the crank 16 axis, the piston side force of the first cylinder 1 shows a considerably large value, and the piston side force of the second cylinder 2 has a relatively small value. On the contrary, when there is an offset, the first and second cylinders have the same side force and the maximum value of the side force is kept low. Here, when the piston side force increases, the frictional force between the piston and the cylinder rapidly increases, and when the frictional force exceeds a predetermined value, the smoothness of sliding of the piston is adversely affected. Therefore,
In order to reduce the maximum frictional force between the first and second cylinders 1 and 2, it is sufficient to keep the maximum value of the piston side force low. Therefore, the crankshaft 16 is offset by the same amount as in the present embodiment. By offsetting by e, the piston side forces of the first cylinder 1 and the second cylinder 2 can be made uniform and the maximum frictional force can be reduced.

As shown in FIG. 2, if the exhaust manifold 6 is divided into front and rear parts (or two front and rear parts may be used), intake and exhaust can be alternately repeated before and after. The output performance of the engine can be improved by utilizing the pulsating effect of exhaust gas. Further, in the present embodiment, a four-cylinder, four-cycle engine has been described as an example, but the engine length in the crankshaft direction is not limited to that of the conventional one, even if the number of cylinders is increased to six, ten, and so on. It is half the size of an in-line engine, and its width is considerably narrower than conventional V-type engines and horizontally opposed engines. Also, from the viewpoint of collision safety, if the engine room is filled with something that does not collapse at the time of a collision, such as an engine, the impact force at the time of the collision cannot be absorbed, but the engine according to the present embodiment is mounted. As a result, since the engine width is narrow, a large crushable zone capable of absorbing the impact force at the time of a collision can be secured, so that collision safety can be improved. It goes without saying that the invention can be applied not only to the 4-cycle engine but also to the 2-cycle engine.

[0014]

According to the present invention as set forth in claim 1, the first and second cylinders are arranged in parallel, and the crankshaft is arranged between both central axes of the first and second cylinders. It can be made more compact than the conventional horizontally opposed Scotch yoke engine. As a result, when mounted on an actual vehicle, it is possible to increase the degree of freedom in the layout of the center of gravity of the engine that affects the dynamic performance of the vehicle, and because the cylinder head can be made compact, a low-cost, lightweight, highly rigid engine. Becomes

According to the second aspect of the present invention, even if a difference in thermal expansion occurs between the yoke and the first and second cylinders, the inclination of the yoke is reduced and the difference in thermal expansion is absorbed. It is possible to reduce the stress and strain inside the engine. Moreover, it is possible to prevent the engine from stopping due to the difference in thermal expansion between the engines and the clearance in the engine being lost. According to the invention of claim 3,
Immediately after the combustion state in which the piston side force will be maximized, the crankshaft is eccentric so that the crankpin is located between the center axis of the first cylinder and the center axis of the second cylinder. By doing so, the maximum piston side force of the first and second cylinders can be made uniform, and the maximum value of the piston side force can be suppressed to a low value. As a result, the frictional force due to the piston side force can be suppressed to a low level, resulting in a highly efficient engine.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a 4-cycle 4-cylinder Scotch-yoke engine from above the cylinder head.

FIG. 2 is a side sectional view of a Scotch yoke type engine.

FIG. 3 is a front sectional view of a Scotch yoke type engine (0 ° after top dead center).

FIG. 4 is a front sectional view of a Scotch yoke type engine (90 ° after top dead center).

FIG. 5 is a front sectional view of a Scotch yoke engine (180 ° after top dead center).

FIG. 6 is a front sectional view of a Scotch yoke engine (270 ° after top dead center).

FIG. 7 is an assembly diagram of a Scotch yoke type engine.

FIG. 8 is a relationship diagram between a crankshaft offset amount e and a piston side force.

[Explanation of symbols]

 1 ... 1st cylinder 2 ... 2nd cylinder 3 ... 3rd cylinder 4 ... 4th cylinder 5 ... Intake manifold 6 ... Exhaust manifold 7 ... 1st piston 8 ...・ Intake valve 9 ・ ・ ・ Exhaust valve 10 ・ ・ ・ Second piston 11 ・ ・ ・ First piston pin 12 ・ ・ ・ Second piston pin 13 ・ ・ ・ Yoke 14 ・ ・ ・ Slider 15 ・ ・ ・ Long hole 16 ・・ ・ Crankshaft 17 ・ ・ ・ Third piston 18 ・ ・ ・ Fourth piston 19 ・ ・ ・ Block 20 ・ ・ ・ Crank pin 21 ・ ・ ・ Cylinder head 22 ・ ・ ・ Camshaft 23 ・ ・ ・ Oil pan 24 ・ ・・ Water jacket 25 ・ ・ ・ Piston ring 26 ・ ・ ・ Cylinder skirt 11 '・ ・ ・ Piston pin hole 12' ・ ・ ・ Piston pin hole

Claims (3)

[Claims] 1. A first and a second cylinder, and a first piston and a second piston which are reciprocally provided in the first cylinder and the second cylinder, respectively.
In a Scotch-yoke type engine provided with a yoke for transmitting the reciprocating motions of the first and second pistons to a crankpin of a crankshaft, the moving directions of the first piston and the second piston are parallel in each stroke of the engine. The first and second cylinders are arranged in the same direction, and the axis of the crankshaft is arranged in a direction perpendicular to a plane including the central axes of the first and second cylinders. Is a Scotch-yoke type engine. 2. A first piston pin connecting the first piston and the yoke and a second piston pin connecting the second piston and the yoke are arranged so as to be displaced in the reciprocating direction. The Scotch yoke type engine according to claim 1, characterized in that. 3. The crank pin is positioned between the center axis of the first cylinder and the center axis of the second cylinder immediately after the combustion state in the first or second cylinder. The scotch yoke type engine according to claim 1, wherein the axis of the crankshaft is deviated.