WO2008098433A1

WO2008098433A1 - An overhead camshaft engine

Info

Publication number: WO2008098433A1
Application number: PCT/CN2007/001846
Authority: WO
Inventors: Donggao Qian
Original assignee: Wuxi Southeast Vehicle Technology Co., Ltd
Priority date: 2007-02-14
Filing date: 2007-06-11
Publication date: 2008-08-21
Also published as: CN101012760A

Abstract

An overhead camshaft engine comprising: a cylinder body (1), a cylinder head (1-2), and a crankcase, a connecting rod (4) connecting a crank (3) to a piston (5); wherein an intake valve (7) and an exhaust valve (8) are mounted perpendicularly at the cylinder head, the intake valve is parallel to the exhaust valve, an exhaust camshaft (28) and an exhaust cam (29-2) are mounted between the intake valve and the exhaust valve, a bracket body (32) is connected to the upper end of the cylinder head, an intake camshaft and an intake cam are mounted on the bracket body, the exhaust camshaft and the cam surface of the intake camshaft control separately open and close of the intake valve and the exhaust valve by a rocker (30, 42), the exhaust camshaft connects with the crank by a transmission (30), and the intake camshaft connects with the exhaust camshaft by a transmission.

Description

Overhead cam engine

This invention relates to cam-type gasoline engines, and more particularly to cam-type gasoline engines in which cams are placed on top of the engine. Background technique

The existing overhead cam engine includes a cylinder block, and a lower portion of the cylinder block is connected to the crankcase. In the crankcase and the cylinder block, the crankshaft is connected to the piston through a connecting rod device; an integrated cylinder head and a cylinder are connected at an upper portion of the cylinder block. The space between the bottom surface of the head and the piston is a combustion chamber, and a valve actuation control device for opening and closing the intake valve, the exhaust valve and both of them is disposed above the combustion chamber at a position of the cylinder head. The valve actuation control device is a cam control device. The camshaft and the cam are mounted on the cylinder head portion. The crankshaft drives the cam to rotate through the transmission device. The cam contacts one end of the rocker arm, and the other end of the rocker arm and the intake valve or The exhaust valve control lever is connected to control the opening or closing of the intake or exhaust valve. The cam control device described above is mounted on the cylinder head and is referred to as an overhead cam engine.

U.S. Patent No. 5,706,769 discloses a single cam structure overhead cam engine that shares a single cam mounted to the cylinder head to control the opening and closing of the intake and exhaust valves, a single cam The axis of the cylinder intersects the axis of the cylinder vertically; the center lines of the intake valve and the exhaust valve are parallel to each other, symmetrically and vertically distributed on both sides of the axis of the single cam; the cam faces of the single cam pass through the two rocker arms are respectively Control of opening and closing of intake and exhaust valves. This single-cam cam structure overhead cam engine allows the engine to have a smaller head and also reduces some manufacturing costs. However, the cam engine of the single cam structure uses a cam to separately control the opening and closing of the intake valve and the exhaust valve, and the single cam has a large working load and a short service life; meanwhile, a cam is used to separately control The opening and closing of the gas valve and the exhaust valve make it difficult to achieve a reasonable valve phase for opening and closing between the intake valve and the exhaust valve, and it is difficult to accurately and timely cooperate with the opening and closing. Summary of the invention

The cam engine for a single cam structure has a large single working load and is difficult to meet the intake air. The problem of reasonable valve timing requirements for opening and closing of valves and exhaust valves has been improved by the applicant, providing another overhead cam engine with a small cam load and easy access to the intake and exhaust valves. It has a reasonable valve timing when closed, and the head of the engine also has a small lateral dimension.

The technical solution of the present invention is as follows:

The overhead cam engine includes a cylinder block, the cylinder block is connected to the crankcase, and the crankshaft is connected to the piston through the connecting rod device in the crankcase and the cylinder block; an integrated cylinder head is connected to the upper part of the cylinder block, and the combustion chamber is in the cylinder block An intake valve and an exhaust valve whose center lines are parallel to each other are vertically installed at a position above the cylinder head; a first cam shaft parallel to the crankshaft is mounted between the intake valve and the exhaust valve, the first camshaft The axis of the cylinder is perpendicularly intersected with the central axis of the cylinder block, the upper end of the cylinder head is connected to the bracket body, and the second cam shaft parallel to the crankshaft is mounted on the bracket body, and the first cam and the second cam are respectively mounted on the two cam shafts; The cam faces of the cam and the second cam are respectively in contact with one ends of the two rocker arms, and the other ends of the two rocker arms are respectively in contact with the valve control rods of the intake valve or the exhaust valve; the first camshaft is connected to the crankshaft through the transmission device, The two camshafts are coupled to the first camshaft by a transmission. It may be that the first camshaft is coupled to the crankshaft by a pulley drive and the second camshaft is coupled to the first camshaft by a sprocket drive. In the sprocket transmission device, the tensioning device of the transmission chain is a leaf spring, one end of the leaf spring is fastened to the bracket body at the upper end of the cylinder head, and the other end of the leaf spring is elastically bowed on the transmission chain.

In the overhead cam engine, the opening and closing of the intake valve and the exhaust valve are respectively controlled by the intake cam and the exhaust cam through the rocker arm, that is, controlled by the double cam, effectively reducing the working load of the control cam and improving the control. The working life of the cam. Secondly, the two cams respectively control the opening and closing of the intake valve and the exhaust valve, and are easy to adjust and achieve a reasonable valve timing when the intake valve and the exhaust wide open and close. The intake valve and the exhaust valve are parallel to each other and vertically mounted to the cylinder head, and the exhaust camshaft and the exhaust cam are installed between the intake valve and the exhaust valve, and the intake camshaft and the intake cam are mounted on the cylinder The bracket body on the upper part of the head effectively reduces the lateral dimension of the cylinder head. DRAWINGS

Figure 1 is a cross-sectional view showing the structure of the present invention, taken along the line A-A of Figure 2;

Figure 2 is a cross-sectional view taken along line B- B of Figure 1;

Figure 3 is a cross-sectional view taken along line C-C of Figure 1; Referring to Fig. 1, the present invention includes a cylinder block 1. The lower portion of the cylinder block 1 is connected to a crankcase. In the crankcase and the cylinder block 1, the crankshaft 3 is connected to the piston 5 through a connecting rod device; the cylinder block 1 includes a cylinder outer wall 1-1. And the cylinder sleeve 1-5 integrally molded with the same, the bearing bush 1-3 is pressed on the outer wall 1-1 of the cylinder, and the inclined surface 1-4 of the cylinder block 1 is combined with the inclined surface 2-2 of the oil base 2 to form a crankcase. And connected by a screw 15; connected to the upper part of the cylinder block 1 with a cylinder head 1-2;

The two shaft diameters 3-1 and 3-2 of the crankshaft 3 are respectively supported on the bearing pads 1-3 of the cylinder block 1 and the bearing pads 2-1 of the oil base 2; the flywheel 16 is fixed to one end of the crankshaft 3 in a conventional manner;

One end of the piston 5 and the connecting rod 4 is connected by a piston pin 6, the piston 5 can be rotated on the piston pin 6; the other end of the connecting rod is connected with the crank 3-3 of the crankshaft, and the end of the connecting rod can be rotated along the crank 3 - 3 The piston 5 can reciprocate in the cylinder liner 1-5; the combustion chamber 16 is defined as the portion between the piston 5 and the bottom surface of the cylinder head 1-2.

As shown in Fig. 2, a large number of fins are distributed on the outer wall 1-1 of the cylinder. As shown in Figures 3 and 1, the intake valve 7 is in contact with the intake valve seat 9 to control the opening and closing of the intake port, and the intake port extends from the intake valve seat 9 to a side of the cylinder head 17 The side surface 17 is connected to the heat shield 22 of the carburetor, the heat shield 22 is connected to the carburetor 20, and the carburetor 20 is connected to the air cleaner 21 to form a fuel mixture formation and supply system; 8 is in contact with the exhaust wide seat 10 to control the opening and closing of the exhaust passage. The exhaust passage extends from the exhaust valve seat ring 10 to the other side 18 of the cylinder head, and the side surface 18 is connected to the muffler 19 to constitute Exhaust gas removal and shutdown system. As shown in FIGS. 3 and 1, the intake valve 7 and the exhaust valve 8 are vertically mounted to the cylinder head 1-2 above the combustion chamber 16 in the cylinder block, and the center lines of the two are parallel to each other and distributed in the center of the cylinder. On both sides of the line, the valve control rod of the intake valve 7 reciprocates up and down along the intake valve guide sleeve 23, and the valve control rod of the exhaust valve 8 reciprocates up and down along the exhaust valve guide sleeve 24, the intake valve 7 A valve spring 25 and a spring retainer 26 are attached to the upper portions of the valve control lever of the valve control lever and the exhaust valve 8, respectively. One end of the valve spring 25 is mounted on the cylinder head 1-2, and the other end is fitted into the spring seat 26. The spring seat 26 is seated in the slot of the valve control lever, and the valve spring 25 biases the spring seat 26 away from the closing direction. . Referring to Fig. 1, the screw port of the spark plug 27 is mounted on the cylinder block above the combustion chamber 16, on the side of the intake valve 7 and the exhaust valve 8.

As shown in FIG. 1, the exhaust camshaft 28 is a first camshaft mounted on the cylinder head 1-2 between the intake air and the exhaust air, and the axis of the exhaust camshaft 28 is parallel to the axis of the crankshaft 3. And intersect perpendicular to the cylinder center axis. An exhaust cam assembly 29 is mounted on the exhaust camshaft 28, and the driven pulley 29-1, the exhaust cam 29-2 as the first cam, and the drive sprocket 29-3 are fastened together on a sleeve to form a row. An air cam assembly 29, the sleeve sleeve is mounted on the exhaust camshaft 28, The exhaust cam assembly 29 is rotatable about the exhaust camshaft 28 by a bushing that is stationary.

The exhaust cam assembly 29 is composed of different materials. The driven pulley 29-1 is made of phenolic plastic, the exhaust cam 29-2 is made of metal, and the drive sprocket 29-3 is also made of metal.

As shown in Fig. 1, the exhaust camshaft 28 is connected to the crankshaft 3 via a pulley transmission, and the pulley transmission is simultaneously used as a governor, which is composed of a timing belt 30, a drive pulley 31 and a driven pulley 29-1. The driving pulley 31 cooperates with the crankshaft, and the crankshaft drives the driving pulley 31 to rotate. The timing belt 30 drives the exhaust cam assembly 29 to rotate. The speed of the exhaust cam assembly 29 is 1/2 of the crankshaft 3 rotation speed, and the rotation direction is the same.

As shown in FIG. 1, the upper end of the cylinder head 1-2 is connected to the bracket body 32, and the intake camshaft 33 as the second camshaft is mounted on the bracket body 32, and the axes of the intake camshaft 33 are parallel to the crankshaft 3 and the row, respectively. The axis of the air camshaft 28, see Fig. 2, the axis of the intake camshaft 33 is offset from the central axis of the cylinder block. As shown in Fig. 1, an intake cam combination 34 is mounted on the intake camshaft 33. The intake cam assembly 34 includes an intake cam 34-1 and a driven sprocket 34-2. The driving sprocket 29-3 is connected to the driven sprocket 34-2 via the chain 35. The speed ratio of the driven sprocket 34-2 to the driving sprocket 29-3 is 1:1, and the intake camshaft 33 is transmitted through the sprocket. The device is coupled to an exhaust camshaft 28 that is rotatable on the intake camshaft 33.

As shown in FIG. 3, FIG. 2 and FIG. 1, the intake valve rocker arm 11 and the exhaust valve rocker arm 12 are mounted on the cylinder head 1-2 through the intake valve rocker arm shaft 36 and the exhaust valve rocker arm shaft 37, respectively. The hub is distributed on both sides of the exhaust camshaft 28, and the intake valve rocker arm 11 and the exhaust valve rocker arm 12 are rotatable on the intake valve rocker arm shaft 36 and the exhaust valve rocker arm shaft 37, respectively.

As shown in FIG. 2 and FIG. 3, the intake valve rocker arm 11 and the exhaust valve rocker arm 12 each have two crank arms, and one end of the two crank arms is respectively provided with a valve adjusting screw 13 and a lock nut 14 thereof. The arc surface of the lower end portion of the adjusting screw 13 is in contact with the upper end portions of the valve control rods of the intake valve 7 and the exhaust valve 8, respectively; the curved surface of the end of the other crank arm of the exhausting rocker arm 12 and the exhaust cam The cam surface of 29-2 is in contact; the curved surface of the other crank arm end of the intake valve rocker arm 11 is in contact with the cam surface of the intake cam 34-1. The rotation of the intake cam 34-1 and the exhaust cam 29-2 respectively drives the intake valve rocker arm 11 and the exhaust valve rocker arm 12 by the crank arm, thereby being controlled by the adjusting screw 13 thereon. The gas valve 7 and the exhaust valve 8 are opened or closed.

As shown in FIG. 2, in the sprocket transmission device, the tensioning device of the transmission chain 35 is a leaf spring 38, and one end of the leaf spring 38 is fastened to the bracket body 32 at the upper end of the cylinder head, the leaf spring 38 The other end is arcuate, and the elastic bow is placed on the drive chain 35. The above is the preferred embodiment of the invention. The present invention can be applied to an air-cooled single-cylinder engine. Of course, it can also be used for an air-cooled multi-cylinder, a water-cooled single-cylinder, and a multi-cylinder engine. Further, in the above embodiment, the cylinder head and the cylinder block are integrally formed, but they may be independently formed. As a further embodiment, the present invention is also applicable to mounting an intake camshaft and an intake cam on a cylinder head 1-2, and an exhaust camshaft and an exhaust cam are mounted on the bracket body 32.

The invention is applicable to an engine for a lawn mower and to other engines for related purposes.

Claims

Claim

1. An overhead cam engine comprising a cylinder block, the cylinder block being connected to the crankcase, in the crankcase and the cylinder block, the crankshaft is connected to the piston through a connecting rod device; and an integrated cylinder head is connected at an upper portion of the cylinder block, wherein: An intake valve and an exhaust valve whose center lines are parallel to each other are vertically installed at a position above the combustion chamber in the cylinder block; a first cam parallel to the crankshaft is mounted between the intake valve and the exhaust valve a shaft, an axis of the first camshaft intersects with a central axis of the cylinder block, an upper end of the cylinder head is connected to the bracket body, and a second cam shaft parallel to the crankshaft is mounted on the bracket body, and the first cam is respectively mounted on the two camshafts a second cam; the cam faces of the first cam and the second cam are respectively in contact with one ends of the two rocker arms, and the other ends of the two rocker arms are respectively in contact with the valve control rods of the intake valve or the exhaust valve; the first camshaft passes through the transmission The device is coupled to the crankshaft and the second camshaft is coupled to the first camshaft by a transmission.

2. The overhead cam engine according to claim 1, wherein said first camshaft and said first cam are an exhaust camshaft and an exhaust cam, and said second camshaft and said second cam are intake camshafts. And intake cam.

3. An overhead cam engine according to claim 1 or 2, wherein said first camshaft is coupled to the crankshaft by a pulley drive and the second camshaft is coupled to the first camshaft by a sprocket drive.

4. The overhead cam engine according to claim 3, wherein in the sprocket transmission, the tensioning device of the transmission chain is a leaf spring, and one end of the leaf spring is fastened to the bracket connected to the upper end of the cylinder head. Body, the other end of the leaf spring is elastically arched on the drive chain.

The overhead cam engine according to claim 1 or 2, wherein said first cam has a cam surface made of a metal material.