A starting decompression device for a motorcycle engine

Abstract

The present invention provides a starting and decompression device for a motorcycle engine, which belongs to the technical field of motorcycle engine manufacturing. It solves the problem of how to improve the reliability of the starting and decompression device. The device includes a mounting plate, a decompression valve rod and a tension spring. Two swing blocks are hinged on the mounting plate. An external limit structure for limiting the swing amplitude of the swing block is provided between the outer side of each swing block and the mounting plate. The two ends of the tension spring are respectively fixed to the two swing blocks. The inner side of each swing block has a hook portion extending toward the opposite swing block. The two hook portions have a tendency to swing inward under the tension of the tension spring and abut against their respective corresponding swing blocks. A linkage structure is provided between each hook portion and the decompression valve rod. The two swing blocks in the device have good swing synchronization and can be limited and clamped by abutting against each other. The control of starting and decompression has good stability, which makes the device have good reliability.

Description

Technical Field

[0001] The invention belongs to the technical field of motorcycle engine manufacturing and relates to a starting decompression device for a motorcycle engine. Background Art

[0002] When a motorcycle engine is started, it needs to inhale new gas for compression. Near the end of the compression, a large compression resistance will be generated. If the pressure is not reduced at this time, the starting force will increase, making starting very difficult. Therefore, most existing engines are equipped with a starting pressure relief device to relieve pressure to ensure a smooth engine start, achieve easy starting, and extend the life of the starter motor.

[0003] At present, the commonly used starting decompression devices are of the "centrifugal block + balance block" type. For example, the applicant has designed and developed a motorcycle engine starting decompression structure and applied for a patent with the publication number CN112412569A. The starting decompression structure includes a camshaft, a sprocket and a pressure reducing valve assembly. The sprocket is provided with a fastener and the sprocket is fixedly connected to the camshaft through the fastener. The pressure reducing valve assembly includes a throw block arranged on the side of the sprocket, one end of the throw block is hinged to the sprocket and the throw block can be thrown out in the radial direction of the sprocket under the action of centrifugal force. A reset elastic member is connected to the throw block, and the throw block is reset under the action of the reset elastic member and rests against the tight On the hardware, a limiting protrusion is provided at the edge of the sprocket. After the swing block is swung out, the hinged end of the swing block abuts against the limiting protrusion, thereby limiting the swing stroke of the swing block. The camshaft has an exhaust cam, and a center hole is axially provided in the camshaft. A pin hole connected to the center hole is radially provided on the exhaust cam. The pressure reducing valve assembly also includes a pressure reducing pin provided in the pin hole and a pressure reducing valve stem provided in the center hole and connected to the pressure reducing pin. One end of the pressure reducing valve has a linkage disk extending into the mounting hole of the sprocket. The linkage disk is provided with two detent pins. The hinged parts of the two swing blocks are provided with notches. The two detent pins are plugged into the notches of the two swing blocks in a one-to-one correspondence. This pressure reducing structure enables the sprocket assembly to achieve a lightweight design while also having the advantage of a compact structure.

[0004] However, with the development of starting technology, the above-mentioned starting decompression structure still has some shortcomings: the two swing blocks are independently hinged on the sprocket, and the swing blocks are reset by torsion springs. Since the elastic properties of the torsion springs are restricted by manufacturing and installation, the elastic properties of the two torsion springs cannot be consistent, which results in different reaction forces on the two swing blocks, resulting in poor synchronization of the two swing blocks, causing the combined force applied by the two to the push pin to be unstable, which will cause the moving stroke of the push pin to be unstable, affecting the reliability of the starting decompression structure; at the same time, when in the closed state, the two swing blocks are limited by their corresponding fastening bolts. Since the fastening bolts will become loose, the limiting of the two swing blocks is unreliable. In addition, the above-mentioned torsion spring factors may cause air leakage under the closed condition due to inaccurate moving stroke of the push pin, thereby causing the decompression structure to be unreliable. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned problems in the existing technology and to propose a starting and decompression device for a motorcycle engine. The technical problem to be solved by the present invention is how to improve the reliability of the starting and decompression device.

[0006] The objectives of the present invention can be achieved through the following technical solutions: a starting and decompressing device for a motorcycle engine, the motorcycle engine includes a camshaft, the starting and decompressing device includes a mounting plate coaxially arranged and fixedly connected to the camshaft and a decompressing valve rod inserted in the mounting plate, two swing blocks are hinged on the mounting plate, and an external limiting structure for limiting the outward swing amplitude of the swing block is provided between the outer side of each swing block and the mounting plate, characterized in that the starting and decompressing device also includes a tension spring, the two ends of the tension spring are respectively fixedly connected to the two swing blocks, the inner side of each swing block has a hook portion extending toward the opposite swing block, the two hook portions have a tendency to swing inward under the tension of the tension spring and abut against their respective corresponding swing blocks, a linkage structure is provided between each of the hook portions and the decompressing valve rod, and the two hook portions can drive the decompressing valve rod to rotate reciprocatingly through their respective corresponding linkage structures.

[0007] Different from the existing technology, this starting and decompression device makes special improvements to the specific structure and limiting method of the swing block, thereby achieving the purpose of improving the reliability of the starting and decompression device. Specifically, the present invention only uses a tension spring to connect the two swing blocks, so that the reaction forces received by the two swing blocks are consistent, thereby making the two swing blocks have better synchronization when they are forced to swing; at the same time, by designing a hook portion extending to the opposite side on the inner side of the swing block, the two hook portions have a tendency to swing inward under the tension of the tension spring and abut against their respective corresponding swing blocks, so that the two swing blocks abut against each other and embrace each other to form a mutual limit, without the need to rely on an external limit structure to limit, and avoid being affected by the external limit structure. Such a limit form makes the two swing blocks form a whole, the structural form is more stable and reliable, and it is not easy to loosen in the non-working state; at the same time, since the hook portion on the swing block in the present device drives the pressure reducing valve stem to rotate back and forth through a linkage structure, then, through the above-mentioned design of the swing block, the stability of the swing block swinging to control the rotation of the pressure reducing valve stem is improved, which will neither cause the pressure reducing valve stem to rotate too large or too small, nor cause the pressure reducing valve stem to suddenly rotate abnormally, thereby improving the reliability of starting the pressure reducing device.

[0008] In the above-mentioned motorcycle engine starting and decompression device, the swing blocks are hook-shaped, and the two swing blocks are arranged end to end along the circumference of the mounting plate. The tail ends of the two swing blocks are respectively hinged to the mounting plate and each forms a hinge point. The two hook portions are located between the two hinge points and abut against the inner side of each corresponding swing block. Through the above design, when the two swing blocks abut against each other through the hook portions to limit the position, the hinge point and the limit point are reasonably arranged, and the limit point is located inside the swing blocks, which can form a more stable whole and is not easily loosened by external interference, thereby further improving the reliability of the device during use.

[0009] In the aforementioned motorcycle engine starting and decompression device, the inner sides of both swing blocks are provided with inner limiting surfaces, and the end surfaces of the two hook portions are both flat surfaces, so that the end surfaces of the two hook portions can abut against the corresponding inner limiting surfaces. The coordinated design of the inner limiting surfaces and the end surfaces of the hook portions makes the limiting abutment between the hook portions and their respective swing blocks more stable and less likely to loosen, thereby further improving the reliability of the device during use.

[0010] In the aforementioned motorcycle engine starting and decompression device, the tension spring is arranged between the two hooks, with the arrangement direction of the tension spring perpendicular to the inner limit surface. A mounting hole is provided in the middle of the swing block, and the two ends of the tension spring are hooked into the corresponding mounting holes. The starting and decompression device needs to remain closed when not in operation. The above design maximizes the tension of the tension spring on the swing block, allowing the two swing blocks to be more effectively and reliably held together when not in operation, preventing them from loosening, thereby improving the reliability of the device.

[0011] In the aforementioned motorcycle engine starting and decompression device, the mounting plate is located at one end of the camshaft, and a sprocket is provided at the other end of the camshaft. This design eliminates the need for components on the mounting plate to be mounted on the sprocket. This reduces the need for a large sprocket cavity and utilizes the space at the other end of the camshaft, thereby ensuring a compact engine structure. Furthermore, since the sprocket's mounting location already requires the installation of components that mate with the sprocket, this design reduces the risk of interference with components on the mounting plate, resulting in relatively ample assembly space and greater ease of assembly.

[0012] In the above-mentioned starting and decompression device of the motorcycle engine, one end of the mounting plate has a cylindrical mounting portion, and one end of the camshaft has a cylindrical matching portion. The matching portion is divided into an adjustment section and a fixed section from the outside to the inside. The mounting portion is sleeved outside the matching portion and tightly matched with the fixed section. The outer diameter of the adjustment section is smaller than the outer diameter of the fixed section. An adjustment gap is formed between the mounting portion and the adjustment section. A key groove for positioning the assembly angle of the mounting plate is provided on the outer periphery of the mounting plate. Unlike the prior art, the mounting plate and camshaft in this device are connected directly via a tight fit, rather than bolted. Specifically, a cylindrical mounting portion is designed at one end of the mounting plate, and a cylindrical mating portion is designed at one end of the camshaft. The tight fit between the mounting portion and the mating portion creates a fixed connection. Furthermore, to ensure the mounting plate can be adjusted, i.e., the mounting plate needs to drive the pressure relief valve stem to adjust the mating position of the pressure relief valve stem with the pressure relief valve body in the pressure relief mechanism, the present invention further designs the mating portion, dividing it from the outside to the inside into an adjustment section and a fixed section. The outer diameter of the adjustment section is smaller than that of the fixed section, creating an adjustment gap between the mounting portion and the adjustment section. Before the mounting plate is secured, the fixed section can be adjusted first, without first pressing in to form a tight fit. Once the adjustment is complete, the fixed end can be pressed in to form a tight fit. This design not only meets the mounting plate's adjustment requirements, but also eliminates the need for tedious operations such as tightening bolts during assembly. Assembly can be completed with a single press, making assembly very convenient. Furthermore, the keyway design can provide a position reference for the assembly operation of the mounting plate, thereby further facilitating the adjustment and fixed assembly of the mounting plate.

[0013] In the aforementioned motorcycle engine starting and decompression device, the linkage structure includes a deactivating pin fixed to the end surface of the decompression valve stem and a U-shaped recess defined within the inner side of a hook portion. The deactivating pin is located within the recess and is capable of sliding along the inner wall of the recess. When the mounting plate rotates with the camshaft, the swing block hinged to the mounting plate is subjected to centrifugal force and oscillates centrifugally. At this time, the decompression valve stem oscillates in conjunction with the recess in the hook portion and the deactivating pin, ultimately driving the decompression pin in the starting device to extend and retract, thereby opening or closing the valve.

[0014] As an alternative, in the aforementioned motorcycle engine starting and decompression device, the linkage structure includes a pull rope disposed between the hook portion and the end face of the decompression valve stem, with one end of the pull rope being fixedly connected to the hook portion and the other end of the pull rope being fixedly connected to the end face of the decompression valve stem. This pull rope design can also achieve linkage between the swing block and the decompression valve stem.

[0015] In the aforementioned motorcycle engine starting and decompression device, the outer limiting structure includes an annular flange located on the outer edge of the mounting plate. The swing block is located within the annular flange, and the outer side of the swing block has an arc-shaped limiting portion that can abut against the annular flange. The coordinated design of the annular flange and the limiting portion can limit the centrifugal outward swinging distance of the swing block, thereby preventing the pressure reducing valve stem from rotating excessively, thereby ensuring the reliability of the device.

[0016] As an alternative, in the aforementioned motorcycle engine starting and decompression device, the outer limiting structure includes a stopper secured to the outer peripheral edge of the mounting plate, and the outer side of the swing block includes an arc-shaped limiting portion, which is capable of abutting against the stopper. The coordinated design of the stopper and limiting portion can also limit the centrifugal outward swinging distance of the swing block, thereby preventing the pressure reducing valve stem from rotating excessively, thereby ensuring the reliability of the device.

[0017] Compared with the existing technology, the starting and decompression device of the motorcycle engine has the following advantages: 1. The swing synchronization of the two swing blocks in the starting and decompression device is good, and they can be limited and clamped by abutting against each other, which has good stability for the control of starting and decompression, thereby making the device have good reliability; 2. By improving the connection method between the mounting plate and the camshaft, the starting and decompression device meets the phase adjustment requirements while eliminating the need for tedious operations such as tightening bolts during assembly. The assembly action can be completed with just one press, which is very convenient and greatly improves the assembly efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the structural diagram of the starting pressure reducing device Figure 1 .

[0019] Figure 2This is the structural diagram of the starting pressure reducing device Figure 2 .

[0020] Figure 3 It is a structural diagram of the swing block in the starting and decompression device.

[0021] Figure 4 It is a partial structural cross-sectional view of the starting pressure reducing device.

[0022] Figure 5 yes Figure 4 A partial enlarged view of point A in the middle.

[0023] In the figure, 1. camshaft; 11. mating part; 111. adjusting section; 112. fixing section; 2. mounting plate; 21. mounting part; 22. keyway; 23. annular flange; 3. pressure reducing valve stem; 4. swing block; 41. hook part; 42. inner limit surface; 43. mounting hole; 44. notch; 45. limit part; 5. tension spring; 6. sprocket; 7. push pin. DETAILED DESCRIPTION

[0024] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0025] Specifically, if Figure 1 and Figure 2 As shown, the motorcycle engine includes a camshaft 1. The starting decompression device includes a mounting plate 2 coaxially arranged and fixedly connected to the camshaft 1, and a pressure reducing valve rod 3 extending through the mounting plate 2. The mounting plate 2 is located at one end of the camshaft 1, and a sprocket 6 is provided at the other end of the camshaft 1. Two hook-shaped swinging blocks 4 are hingedly connected to the mounting plate 2. The two swinging blocks 4 are arranged end to end relative to each other along the circumference of the mounting plate 2, and the tail end of each swinging block 4 is hingedly connected to the mounting plate 2 to form a hinge point. The starting decompression device also includes a tension spring 5, the ends of the tension spring 5 being fixedly connected to the two swinging blocks 4, respectively. The inner side of each swinging block 4 has a hook portion 41 extending toward the opposite swinging block 4. The two hook portions 41 are located between the two hinge points and tend to swing inward under the tension of the tension spring 5 and abut against their respective swinging blocks 4. At the same time, a linkage structure is provided between each hook portion 41 and the pressure reducing valve stem 3. The linkage structure includes a pin 7 fixedly connected to the end face of the pressure reducing valve stem 3 and a U-shaped recess 44 provided on the inner side of the hook portion 41. The pin 7 is located in the recess 44 and can slide along the inner wall of the recess 44. The two hook portions 41 can drive the pressure reducing valve stem 3 to rotate back and forth through their respective corresponding linkage structures.

[0026] For example Figure 2 and Figure 3As shown, in this embodiment, an external limiting structure for limiting the outward swing amplitude of the swing block 4 is provided between the outer side of each swing block 4 and the mounting plate 2. The external limiting structure includes an annular flange 23 located on the outer peripheral edge of the mounting plate 2. The swing block 4 is located inside the annular flange 23 and the outer side of the swing block 4 has an arc-shaped limiting portion 45, which can abut against the annular flange 23. The inner sides of the two swing blocks 4 are both provided with an inner limiting surface 42, and the end faces of the two hook portions 41 are both flat. The end faces of the two hook portions 41 and the corresponding inner limiting surfaces 42 can abut against each other. The tension spring 5 is arranged between the two hook portions 41, and the arrangement direction of the tension spring 5 is perpendicular to the inner limiting surface 42. A mounting hole 43 is provided in the middle of the swing block 4, and the two ends of the tension spring 5 are respectively hooked in the corresponding mounting holes 43.

[0027] For example Figure 4 and Figure 5 As shown, in this embodiment, one end of the mounting plate 2 has a cylindrical mounting portion 21, and one end of the camshaft 1 has a cylindrical matching portion 11. The matching portion 11 is divided into an adjustment section 111 and a fixed section 112 from the outside to the inside. The mounting portion 21 is sleeved on the outside of the matching portion 11 and tightly fitted with the fixed section 112. The outer diameter of the adjustment section 111 is smaller than the outer diameter of the fixed section 112. An adjustment gap is formed between the mounting portion 21 and the adjustment section 111. A key groove 22 for positioning the assembly angle of the mounting plate 2 is provided on the outer periphery of the mounting plate 2.

[0028] Alternatively, the outer limiting structure may include a stopper fixed to the outer edge of the mounting plate 2, with the outer side of the swing block 4 having an arc-shaped limiting portion 45 capable of abutting against the stopper. The linkage structure may also include a pull rope disposed between the hook portion 41 and the end face of the pressure reducing valve stem 3, with one end of the pull rope being fixedly connected to the hook portion 41 and the other end of the pull rope being fixedly connected to the end face of the pressure reducing valve stem 3.

[0029] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

[0030] Although this document frequently uses terms such as camshaft 1, mating portion 11, adjustment section 111, fixing section 112, mounting plate 2, mounting portion 21, keyway 22, annular flange 23, pressure reducing valve stem 3, swing block 4, hook portion 41, inner limiting surface 42, mounting hole 43, notch 44, limiting portion 45, tension spring 5, sprocket 6, and detent pin 7, the use of other terms is not excluded. These terms are used solely to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitations would be contrary to the spirit of the present invention.

Claims

1. A starting decompression device for a motorcycle engine, the motorcycle engine comprising a camshaft (1), the starting decompression device comprising a mounting plate (2) coaxially arranged and fixedly connected to the camshaft (1) and a decompression valve rod (3) penetrating the mounting plate (2), two swing blocks (4) being hingedly connected to the mounting plate (2), an outer limit structure for limiting the swing amplitude of the swing block (4) being provided between the outer side of each swing block (4) and the mounting plate (2), and the invention is characterized in that: The start-up pressure reducing device further comprises a tension spring (5), the two ends of the tension spring (5) are respectively fixedly connected to the two swing blocks (4), the inner side of each swing block (4) has a hook portion (41) extending toward the opposite swing block (4), the two hook portions (41) have a tendency to swing inward under the tension of the tension spring (5) and abut against the respective corresponding swing blocks (4), a linkage structure is provided between each of the hook portions (41) and the pressure reducing valve rod (3), and the two hook portions (41) can drive the pressure reducing valve rod (3) to rotate back and forth through the respective corresponding linkage structures; the swing blocks (4) are in the shape of a hook, and the two swing blocks (4) are arranged end to end relative to each other along the circumference of the mounting plate (2). The tail ends of the two swing blocks (4) are respectively hinged to the mounting plate (2) and each forms a hinge point. The two hook portions (41) are located between the two hinge points and abut against the inner sides of the corresponding swing blocks (4). The inner sides of the two swing blocks (4) each have an inner limit surface (42). The end surfaces of the two hook portions (41) are both planes. The end surfaces of the two hook portions (41) and the corresponding inner limit surfaces (42) can abut against each other. The linkage structure includes a detent pin (7) fixedly connected to the end surface of the pressure reducing valve stem (3) and a U-shaped recess (44) provided on the inner side of the hook portion (41). The detent pin (7) is located in the recess (44) and can slide along the inner wall of the recess (44).

2. The starting decompression device for a motorcycle engine according to claim 1, characterized in that: The tension spring (5) is arranged between the two hook portions (41), and the arrangement direction of the tension spring (5) is perpendicular to the inner limit surface (42). A mounting hole (43) is provided in the middle of the swing block (4), and both ends of the tension spring (5) are respectively hooked in the corresponding mounting holes (43).

3. The starting decompression device for a motorcycle engine according to claim 1 or 2, characterized in that: The mounting plate (2) is located at one end of the camshaft (1), and a sprocket (6) is provided at the other end of the camshaft (1).

4. The starting decompression device for a motorcycle engine according to claim 1 or 2, characterized in that: One end of the mounting plate (2) has a cylindrical mounting portion (21), and one end of the camshaft (1) has a cylindrical matching portion (11), wherein the matching portion (11) is sequentially divided into an adjustment section (111) and a fixed section (112) from the outside to the inside. The mounting portion (21) is sleeved outside the matching portion (11) and tightly matched with the fixed section (112). The outer diameter of the adjustment section (111) is smaller than the outer diameter of the fixed section (112). An adjustment gap is formed between the mounting portion (21) and the adjustment section (111). A keyway (22) for positioning the assembly angle of the mounting plate (2) is provided on the outer periphery of the mounting plate (2).

5. The starting decompression device for a motorcycle engine according to claim 1 or 2, characterized in that: The outer limiting structure comprises an annular flange (23) located on the outer peripheral edge of the mounting plate (2); the swing block (4) is located within the annular flange (23); and the outer side of the swing block (4) has an arc-shaped limiting portion (45), and the limiting portion (45) can abut against the annular flange (23).

6. The starting decompression device for a motorcycle engine according to claim 1 or 2, characterized in that: The outer limiting structure comprises a stopper fixed on the outer peripheral edge of the mounting plate (2); the outer side of the swing block (4) has an arc-shaped limiting portion (45), and the limiting portion (45) can abut against the stopper.

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