KR100600581B1 - method for determinating track of cam and hump-track part for a cam type engine - Google Patents

Abstract

In the cam-based engine of the cam-type engine and the hump track portion of the cam-type engine according to the present invention, in a cam-type engine in which a roller rolls on a cam track surface (CT) having a plurality of hills and valleys, Radius R ₁ , radius R ₂ of the inscribed circle inscribed in the valley of the cam track surface, radius R _a of the peak circle coinciding with the peak surface of the cam while inscribed to the circumscribed circle, and cam circumscribed to the peak circle and the inscribed circle. of the radius R _b of the valley circle matching the valley side, the cam track surface (CT) for riding roll main radius R of the same main circle and the rollers and, while having the same center and the auxiliary rollers cell in contact with the main source won By determining the trajectory of the cam and hump tracks in a simple way, via the radius r of, the design and manufacture of the cams and hump tracks with the optimum trajectory is easy, This has the effect of the shape of the profile tracks at best.

Description

Method for determinating track of cam and hump-track part for a cam type engine

1 is a schematic front sectional view of a cam type engine to which the present invention is applied;

2 is a schematic side cross-sectional view of a cam engine to which the present invention is applied;

3 is an explanatory diagram for deriving a formula for determining a trajectory for a cam track surface having four peaks and valleys;

4 is an explanatory diagram for deriving a formula for determining an optimal radius of a peak circle in FIG.

5 is an explanatory diagram for determining a coordinate point in FIG. 4;

6a to 6c are views illustrating a method of constructing a hump track track groove based on a cam track surface in the present invention;

7 is an explanatory diagram for deriving the relationship between the cam track surface and the locus line of the hump track track groove in the present invention;

8 is an explanatory diagram for deriving a formula for determining a trajectory for a cam track surface having six peaks and valleys.

 <Description of Symbols for Main Parts of Drawings>

CT: Cam track surface ST: Track line of hump track track groove

MR: main circle of main roller SP: cell circle

SR: secondary circle of secondary roller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam type engine, and more particularly, to a method for determining a track of a cam and a hump track portion of a cam type engine.

Conventionally, gasoline engines and diesel engines have a piston-crankshaft mechanism in which a piston and a crankshaft are connected by connecting rods in order to convert the linear motion of the reciprocating piston into a rotational motion in the cylinder. In a four-stroke engine, two reciprocating motions of the piston cause one crankshaft to explode once during a four-stroke cycle of intake, compression, expansion, and exhaust.

Such a reciprocating engine has a limitation in obtaining a large output because a single explosion occurs between two reciprocating motions of the piston, and the maximum value of this side pressure is large because the inertia force of the connecting rod acts on the piston in addition to the reaction force of the output torque. Friction and impact on the cylinder, and the connecting rod and the connection between the piston and the crankshaft are continuously applied in different directions, so the material with high strength, rigidity and yield point is required. The use of a and crankshaft limits the engine's weight and weight.

In order to overcome the limitations of such a reciprocating engine, a cam engine is disclosed in Japanese Patent Laid-Open No. 8-4550. In the cam type engine disclosed in Japanese Patent Laid-Open No. Hei 8-4550, since the cam has a curved cam surface, the main roller and the auxiliary roller located at different distances radially from the center of the cam resemble the trajectory curves drawn by the center thereof. In some parts, the two trajectory curves intersect each other. Therefore, in the structure in which the main roller and the auxiliary roller are installed on the piston with the cam rim interposed on the central axis of the piston, the cam is caught and the output shaft is There is a problem that can not be implemented because it can not be rotated.

In order to solve this problem, the main roller rolls on the track surface of the cam and the auxiliary roller rolls on the track groove of the hump track part. Is filed in Korea.

The Korean Patent Application No. 2004-0003761, as shown in Figures 1 and 2, four cylinders 34 in a radial direction around the cam case 32 in a casing formed integrally at intervals of 90 degrees And a piston (36) reciprocating in the cylinder (34), and the cam (40) is attached to the key (42) on the output shaft (38) provided at the center of the cam case (32). The main roller 44 is rotatably installed outside the raceway surface (outer circumferential surface 40a) of the cam 40, and the main roller 44 is fixed to the piston 36. Auxiliary rollers 46 and 48 are provided on the piston 36 so as not to be separated from the raceway surface (outer circumferential surface), and the auxiliary rollers 46 are provided on both sides of the cam 40 in the axial direction. The hump track portions 50 and 52 having the rolling grooves 50a and 52a to be rolled and fixed are fixed to the output shaft 38 by the key 42. It is a structure fixed to the side of the cam 40 by a bolt (not shown).

Each cylinder 34 is provided with intake and exhaust means having intake and exhaust valves 56 and 58 and an ignition means having a spark plug 60. In the case of a diesel engine, the cylinder 34 is provided with suction and exhaust means and fuel injection means.

The output shaft 38 is rotatably supported by the bearing 62 in the cam case 32.

The lower portion of the piston 36 is dug in the middle to form flanges 36a and 36b on both sides, and the main roller 44 is rotatable by the first pin 64 between the flanges 36a and 36b. The auxiliary rollers 46 and 48 are rotatably installed at the lower ends of the flanges 36a and 36b by the second pins 66 and 68. The auxiliary rollers 46 and 48 are coupled to the outer surfaces of the flanges 36a and 36b, and the raceway grooves 50a and 52a are formed on the inner surfaces of the hump track portions 50 and 52.

In the cam engine configured as described above, when the upper piston 36 is referred to as the first piston in FIG. 1 and the second, third, and fourth pistons in the counterclockwise direction, each piston operates in the same manner. When the output shaft 38 starts to rotate and the cam 40 and the hump track portions 50 and 52 rotate in the counterclockwise direction, the main roller 44 which comes into close contact with the track surface 40a of the cam 40 and rolls. ) And the auxiliary rollers 46 and 48 rolling through the track grooves 50a and 52a of the hump track portions 50 and 52 while the piston 36 lowers the cam mount in the state shown in FIG. Is opened, gas, air, and mixed gas flow into the cylinder 34 and reach bottom dead center. The cam 40 and the hump track portions 50 and 52 are further rotated to raise the piston 36 so that the mixed gas in the cylinder 34 is compressed and ignited by the spark plug 60 at the top dead center position to explode. After expansion, the piston 36 descends to reach the bottom dead center and rises again, and the exhaust gas in the cylinder 34 is exhausted through the exhaust valve 58 to be in a state as shown in FIG. In this cycle, four strokes 36 of the piston 40 and the reciprocating tracks 50 and 52 are reciprocated, and four stroke cycles of suction, compression, expansion, and exhaust are performed.

However, the track surface of the cam and the track groove of the hump track are different depending on the cam diagram, the size of the main roller and the auxiliary roller, and the distance from the center of the output shaft to the bottom dead center and the top dead center of the piston. There was a problem that it was not easy. In particular, in order for the main roller to smoothly ride and roll the track surface of the cam, it is necessary to make the track surface and the track grooves in an optimal shape.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to design and manufacture by determining the trajectory of the cam and hump tracks in a simple manner and presenting the relationship between the cam and hump tracks having an optimal trajectory. The present invention provides a method for determining a cam and a hump track portion of a cam engine that is easy to optimize the shape of a cam and a hump track.

In the cam track determination method of the cam engine according to the present invention, an even number (four in the illustrated embodiment) of the cylinders 34 in the radial direction around the cam case 32 is equally spaced (in the illustrated embodiment). A casing 30 integrally formed at intervals of 90 degrees, and a reciprocating piston 36 is provided in the cylinder 34, and the output shaft 38 provided at the center of the cam case 32 is provided. The cam 40 is fixed by the key 42, and the piston 36 is rotatably installed on the cam raceway surface CT of the cam 40 so that the main roller 44 is rotatably installed. Auxiliary rollers 46 and 48 are provided on the piston 36 so that 44 does not leave the cam raceway CT and pulls down the piston, and both sides of the cam 40 are axially supported. The hump track portions 50 and 52 having the track grooves 50a and 52a which the roller 46 rides and rolls are connected to the output shaft 38. On the other hand in that the fixed bolt (42) in the cam-type engine of a fixed structure on the side of the cam 40,

The radius of the circumscribed circle circumscribed to the peak of the cam track surface is called R ₁ , and the radius of the circumscribed circle circumscribed to the valley of the cam track surface is referred to as R ₂ . The radius is R _a , the radius of the valley circle coinciding with the valley surface of the cam while circumscribed to the peak circle and the inscribed circle is R _b , and the coordinates of the contact point P ₁ of the peak circle and the valley circle ( a, b), the coordinates of the contact point P ₃ of the inscribed circle and the valley circle are (γ, γ), and the coordinates of the center of the valley circle (O ₃ ) are (c, c). , Cam track surface CT is characterized in that the following relational expression is satisfied.

The radius (R _a) of the peaks agent preferably satisfies the following expression.

In the track determination method of the hump track part of the cam type engine according to the present invention, an even number (four in the illustrated embodiment) of the cylinders 34 in the radial direction around the cam case 32 are equally spaced (the illustrated embodiment). And a casing 30 integrally formed at intervals of 90 degrees, and a reciprocating piston 36 is installed in the cylinder 34, and an output shaft 38 provided at the center of the cam case 32. The cam 40 is fixed to the key 42, and the piston 36 is rotatably installed on the cam raceway surface CT of the cam 40 so that the main roller 44 is rotatably installed. Auxiliary rollers 46 and 48 are provided on the piston 36 to prevent the 44 from escaping from the cam raceway surface CT, and on both sides of the cam 40 in the axial direction. Hump track portions 50 and 52 having track grooves 50a and 52a which the auxiliary rollers 46 ride and roll on the output shaft 38. In the cam-type engine of the structure that is fixed to the key 42 and fixed to the side of the cam 40 with a bolt,

The coordinate of the cam track surface CT is referred to as (X, Y), the coordinate of the trajectory line ST which is the centerline of the hump track track groove is referred to as (x, y), and the center O of the cam and the main circle The angle between the straight line connecting the center of (MR) and the x-axis (or X-axis) is called θ, and the distance between the main circle and the locus line on the Y coordinate of the center of the main circle MR is ε, When the radius of the main circle which is the same as the main roller rolling on the cam track surface CT is R, and the radius of the cell circle which is in contact with the main circle having the same center as the auxiliary roller is r, the following relation is satisfied. It is characterized by.

ε = X tan θ-(R + Y)

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is an explanatory diagram for deriving a formula for determining a trajectory for a cam track surface CT having four peaks and valleys at intervals of 90 degrees.

In the drawing, the vertical axis passing through the center of the cam (O) and across the center of the cam mount is called the Y axis, and the horizontal axis passing through the center of the cam (O) is called the X axis, from the center of the cam (O) to the mountain of the cam. The circle circumscribed to the cam track surface CT with the distance of the radius R ₁ is called circumscribed circle, and the cam track has the distance from the center of the cam O to the goal radius R ₂ . A circle inscribed on the surface CT is called an inscribed circle, and a circle having _a radius R _a having _a center (O ₁ , O ₂ ) that coincides with the circumscribed circle and has a center (O ₁ , O ₂ ) is inscribed on the circle. A circle having a radius R _b having a center O ₃ and having a center O ₃ while circumscribing the two peak sources and the inscribed circle between the two peak sources is described below as a 'valley circle'. Is called.

3 is a cam track surface CT having four peaks and valleys at intervals of 90 °, the peak circle having the center O ₁ is located at the center of the Y axis, and the peak circle having the center O ₂ is X. Its center is located on the axis.

The valley circle is in contact with the peaks in the centers O ₁ and O ₂ at the contacts P ₁ and P ₂ , while in contact with the inscribed circle at the contacts P ₃ .

The relational equation of the circle of the peak circle (R _a ), the circumscribed circle (R ₁ ), the inscribed circle (R ₂ ) is represented by the following equations (1, 2, 3).

The equation of the circle of the valley circle R _b is represented by the following equation 4 when the coordinate of the center O ₃ is (c, c).

The valley circle R _b passes through the contacts P _1, P ₂ and P ₃ , and when the coordinates of the contact point are (a, b), (γ, γ), and (b, a), respectively, the contact point Substituting the coordinates of Equation 4 into Equation 4 results in the following Equations 4a, 4b and 4c.

The coordinate value γ of the contact point P ₂ is expressed as follows.

Equations 4a and 4c are equations having the same contents. Solving the same equations (4a) and (4b), the following equation (5) is obtained.

Since the peak circle and the valley circle contact _{each other} at the contact point P ₁ , the derivatives of Equation 4 and Equation 1 are respectively expressed by Equations 6 and 7 below.

Coordinates (a, b) of a contact, so that the gradient of Equation 6 and 7 in the same P _1, is then obtained the formula 6a and 7a in the equation (6) and Equation (7).

If the above equations 6a and 7a are set equally, the following equation 8 is obtained.

On the other hand, since the contact point P ₁ of coordinates (a, b) is a point on Equation 1, the following equation is obtained by substituting coordinates (a, b) into Equation 1.

In summary, the following equation (9) is obtained.

Substituting Equation 9 into Equation 8,

Is obtained, and this expression is summarized as follows.

In the above equation, the c value is expressed as in Equation 10 below.

Then, the valley circle (R _b) is the coordinates (γ, γ) of a contact, because contact with the inscribed circle (R ₂₎ from P _3, there is shown by the following formula 4-2, R _b from equation 4-2 is the following mathematical Equation 11 is shown.

In addition, since the peak circle having _a radius R _a having _a center O ₁ passes through the contact point P ₁ having coordinates (a, b),

Get

From this equation, b is represented by the following expression (12).

Therefore, the radius of the circumscribed circle circumscribed to the peak of the cam track surface is called R ₁ , the radius of the inscribed circle circumscribed to the valley of the cam track surface is referred to as R ₂ , and the peak circle coincides with the peak surface of the cam while inscribed to the circumscribed circle. The radius of R is referred to as R _a , the radius of the valley circle coinciding with the valley surface of the cam while circumscribed to the peak circle and the inscribed circle is R _b , and the coordinates of the contact point between the peak circle and the valley circle are (a, b When the coordinates of the contact point between the inscribed circle and the fraud valley circle are (γ, γ) and the coordinates of the center of the valley circle are (c, c), the cam track surface satisfies the following relational expression. .

Here, a may vary up to R _a . That is, a ≦ R _a is obtained.

R _a until R _b is zero

In other words

가 된다.or

Becomes

Thus, the translation of R _a is

로 주어진다.

Is given by

In the following, given the radius R ₁ of the circumscribed circle and the radius R ₂ of the circumscribed circle, the most suitable peak circle radius is obtained based on the critical condition.

In FIG. 3, a point P ₁ satisfying a = R _a is a contact point between a peak circle satisfying Equation 1 and a valley circle satisfying Equation 4, wherein the contact is parallel to the Y axis and the roller moves in a piston. Since it is orthogonal to the direction, it is a dead spot where the engine cannot be started because there is no vertical component when the engine is rotated by the starter. Therefore, the point that satisfies a = R _a is the critical point. When designing a cam, a must have _a value smaller than R _a (a <R _a ), and b is _a value larger than R ₁ -R _a (b> R _The critical condition with ₁ -R _a ) must be satisfied.

Therefore, the correlation between R ₂ and R _a is also determined by this critical condition. That is, when the circumscribed circle of radius R ₁ and the inscribed circle radius R ₂ of the decision,

로 되어

In

c = R ₁ -R _a .

At the thresholds a = R _a and b = c = R ₁ -R _a , a must be a <R _a and b must satisfy b> R ₁ -R _a .

As shown in Fig. 5, there are two b-values (b ₁ , b ₂ ) for a given value of a, where b> R ₁ -R _a should be taken.

When the critical point, as shown in FIG. 4, that is, peaks circle (R _a) and the valley circle (R _b) is exposed to 90 °, is established the following relationship.

In summary, the following equation (13) is obtained.

Applying the Pythagorean theorem in the triangle consisting of the centers O, O ₁ , O ₃ in Figure 4,

가 된다.

Becomes

If you take a square root on both sides

이 되므로, 다음 수학식 14가 얻어진다.or,

Since the following equation (14) is obtained.

When the equations 13 and 14 are solved the same, the equation 15 is obtained through the following process.

Hereinafter, a method of determining a humtrack quedhome of a cam-type engine that rolls on a cam track surface having a plurality of mountains and valleys and a secondary roller rolls on a hump track track groove having a plurality of mountains and valleys will be described.

When the cam track surface is determined as shown in Fig. 3 or 4, the hump track track groove is determined based on the cam track surface. First, the construction method will be described.

As shown in Fig. 6A, a main circle MR having the same size as the main roller is in contact with the cam track surface on the completed cam track surface CT, and the center of the main circle MR and the center of the cam O are shown. After drawing the straight line (L) connecting the, draw the cell circle (SP) for containing the auxiliary roller to contact the main circle (MR) on the straight line (L), and then the auxiliary circle of the same size as the auxiliary roller ( SR is drawn concentrically with the cell circle SP.

The size of the cell circle SP is determined by how much the main roller (main circle) and the auxiliary roller (secondary circle) are floated.

In this state, as shown in Fig. 6B, while drawing the cell circle SP or the auxiliary circle SR while rotating the straight line L while bringing the main circle MR into contact with the cam track surface CT, As shown in FIG. 6C, a trajectory source can be obtained. When the center of the trajectory source is connected, the trajectory line ST of the hump track track groove can be obtained.

Hereinafter, the relationship between the cam track surface CT and the trajectory line ST of the hump track track groove is obtained.

In FIG. 7, the coordinates of the cam track surface CT are referred to as (X, Y), the coordinates of the trajectory line ST are referred to as (x, y), and the center of the cam O and the main circle MR The angle between the straight line L connecting the center and the x-axis (or X-axis) is θ, and the distance between the main circle and the locus line on the Y coordinate of the center of the main circle MR is ε, and the cam When the radius of the main circle that is the same as the main roller rolling in contact with the raceway CT is R, and the radius of the cell circle which is in contact with the main circle while having the same center as the auxiliary roller is r,

The main circle MR and the cell circle SP satisfy the following equation (16).

When the coordinates of the center of the main circle MR are (ξ, η),

ξ = X ,

이므로

Because of

이다.

to be.

이므로,Thus, in FIG.

Because of,

로 주어진다.

Is given by

8 is an explanatory diagram for deriving a formula for determining a trajectory for a cam track surface CT having six peaks and valleys at 60 ° intervals, in which the symbols are the same as the symbols of FIG. The equation to determine can be derived similarly to the case of four mountains and valleys. Therefore, the equation of the present invention can be applied to the cam track surface having various numbers of peaks and valleys by transforming the X axis into the X 'axis.

According to the trajectory determination method of the cam and hump track portion of a cam engine according to the present invention, the cam and hump tracks are determined by a simple method and the relationship between the cam and hump tracks having an optimal trajectory is presented. It is easy and the shape of a cam and a hump track can be optimized.

Claims (3)

An even number of cylinders 34 in the radial direction are provided around the cam case 32 and have a casing 30 integrally formed at equal intervals, and in the cylinder 34 a reciprocating piston 36 is provided. The cam 40 is fixed to the output shaft 38 provided at the center of the cam case 32 by the key 42, and the piston 36 is external to the cam raceway CT of the cam 40. The main rollers 44 are rotatably installed so that the main rollers 44 do not deviate from the cam track surface CT, and the pistons 36 have auxiliary rollers 46 and 48 to pull down the pistons. And hump track portions 50 and 52 having track grooves 50a and 52a which the auxiliary rollers 46 ride and roll on both sides of the cam 40 in the axial direction. In the cam-type engine of the structure fixed to 42 and fixed to the side of the cam 40 with a bolt, The radius of the circumscribed circle circumscribed to the peak of the cam track surface is called R ₁ , and the radius of the circumscribed circle circumscribed to the valley of the cam track surface is referred to as R ₂ . The radius is R _a , the radius of the valley circle coinciding with the valley surface of the cam while circumscribed to the peak circle and the inscribed circle is R _b , and the coordinates of the contact point P ₁ of the peak circle and the valley circle ( a, b), the coordinates of the contact point P ₃ of the inscribed circle and the valley circle are (γ, γ), and the coordinates of the center of the valley circle (O ₃ ) are (c, c). , Cam track surface CT of the cam track determination method of the cam-type engine, characterized in that the following expression.

The method of claim 1, The radius (R _a ) of the peak source satisfies the following formula: cam cam engine.

An even number of cylinders 34 in the radial direction are provided around the cam case 32 and have a casing 30 integrally formed at equal intervals, and in the cylinder 34 a reciprocating piston 36 is provided. The cam 40 is fixed to the output shaft 38 provided at the center of the cam case 32 by the key 42, and the piston 36 is external to the cam raceway CT of the cam 40. The main rollers 44 are rotatably installed so that the main rollers 44 do not deviate from the cam track surface CT, and the pistons 36 have auxiliary rollers 46 and 48 to pull down the pistons. And hump track portions 50 and 52 having track grooves 50a and 52a which the auxiliary rollers 46 ride and roll on both sides of the cam 40 in the axial direction. In the cam-type engine of the structure fixed to 42 and fixed to the side of the cam 40 with a bolt, The coordinate of the cam track surface CT is referred to as (X, Y), the coordinate of the trajectory line ST which is the centerline of the hump track track groove is referred to as (x, y), and the center of the cam O and the main The angle between the straight line connecting the center of the circle MR and the x-axis (or X-axis) is θ, and the distance between the main circle and the locus line on the Y coordinate of the center of the main circle MR is ε, When the radius of the main circle which is the same as the main roller rolling on the cam track surface CT is R, and the radius of the cell circle which is in contact with the main circle having the same center as the auxiliary roller is r, the following relation is satisfied. A track determination method for a hump track part of a cam engine.

ε = X tan θ- (R + Y)

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