Variable valve timing and valve lift camshaft pressure reducing mechanism and engine

Abstract

The utility model discloses a variable valve timing and valve lift camshaft pressure reducing mechanism and an engine, which comprise a high-low speed cam group, an exhaust cam and a pressure reducing mechanism which are arranged on a camshaft, and the high-low speed cam group comprises a high-speed air inlet cam and a low-speed air inlet cam. The pressure reducing mechanism is arranged between the high-low speed cam group and the timing driven wheel; the pressure reduction mechanism is arranged between the timing driven wheel and the high-low speed cam set, the overall weight of the cam shaft can be reduced, oil consumption is reduced, the structure is more compact, the width of a chain cavity on the timing driven wheel is narrowed, the overall appearance size of an engine is controlled, the pressure reduction mechanism and the cam shaft combination are assembled integrally, and assembling is more convenient.

Description

Technical Field

[0001] The utility model relates to the technical field of camshafts, in particular to a camshaft decompression mechanism with variable valve timing phase and valve lift and an engine. Background Art

[0002] The camshaft is a component in a piston engine. Its function is to control the opening and closing of the valves. It is an important component for the entry and discharge of air into the engine combustion chamber. The camshaft pushes the valve push rod up and down through the cam on it during rotational motion, thereby realizing the opening and closing of the valve. The design of the camshaft has a significant impact on the performance of the engine, including the valve movement law, the engine's power output, torque, and smoothness of operation. As the engine displacement and engine compression ratio gradually increase, the starting torque required by the engine also gradually increases. In order to make the engine easier to start, a decompression mechanism needs to be added to the camshaft.

[0003] In the prior art, in order to achieve variable valve timing and valve lift, a single camshaft is provided with a low-speed intake cam and a high-speed intake cam. The high-speed intake cam and the low-speed intake cam drive the valves under high and low speed conditions to achieve variable valve timing and valve lift. However, due to the increase in the number of cams and the limited space on the camshaft, in order to make the engine easier to start, the decompression mechanism is generally arranged on the outside of the timing driven wheel, which will increase the outer dimensions of the engine's cylinder head and cylinder head cover, increase the overall weight of the engine, increase fuel consumption, and is not conducive to lightweight design.

[0004] Therefore, it is necessary to improve the layout of the existing camshaft decompression mechanism to ensure the realization of variable valve timing and valve lift while reducing the overall weight of the camshaft and narrowing the width of the chain chamber on the timing driven wheel, thereby controlling the overall size of the engine. Utility Model Content

[0005] In view of this, the purpose of the utility model is to provide a camshaft decompression mechanism and an engine with variable valve timing and valve lift, which can ensure the realization of variable valve timing and valve lift while reducing the overall weight of the camshaft and narrowing the chain chamber width on the timing driven wheel, thereby controlling the overall external dimensions of the engine.

[0006] The utility model discloses a camshaft decompression mechanism with variable valve timing phase and valve lift, comprising a high-speed and low-speed cam group, an exhaust cam and a decompression mechanism arranged on the camshaft, wherein the high-speed and low-speed cam group comprises a high-speed intake cam and a low-speed intake cam, and the decompression mechanism is arranged between the high-speed and low-speed cam group and a timing driven wheel.

[0007] Furthermore, the decompression mechanism includes a decompression member arranged next to the exhaust cam of the camshaft and a centrifugal member for driving the decompression member. When the engine is started, the decompression member acts on the exhaust rocker arm to open the exhaust valve. After the engine is started, under the action of the centrifugal member, the decompression member disengages from the exhaust rocker arm.

[0008] Furthermore, the decompression member is a decompression cam that rotates with the exhaust cam, and the centrifugal member is a centrifugal block. The centrifugal block is driven to contact the decompression cam. When the engine is started, the centrifugal block is in an initial position and limits the decompression cam to a position that contacts the exhaust rocker arm and opens the exhaust valve. After the engine is started, the centrifugal block drives the decompression cam to rotate and disengage from the exhaust rocker arm through centrifugal force.

[0009] Furthermore, the centrifugal block is provided with a reset component, and the reset component applies a pre-tightening force to the centrifugal block, and the pre-tightening force makes the centrifugal block have a tendency to return to an initial position.

[0010] Furthermore, the centrifugal block is swingably mounted on the camshaft via a centrifugal block shaft, and the reset assembly comprises a torsion spring, which is sleeved on the centrifugal block shaft to apply a pre-tightening force to the centrifugal block.

[0011] Furthermore, the reset assembly also includes a bushing sleeved on the centrifugal block shaft, and the torsion spring is sleeved on the centrifugal block shaft through the bushing; the centrifugal block shaft is fixed to a set position of the exhaust cam of the camshaft, and the centrifugal block is rotatably mounted on the centrifugal block shaft to form a swingable structure.

[0012] Furthermore, the centrifugal block is in the shape of a large semi-ring, one end of which is a driving end for driving the decompression cam, and the other end is rotatably fitted with a centrifugal block shaft, and the decompression cam is located between the centrifugal block and the exhaust cam.

[0013] Furthermore, a decompression cam shaft is axially extended from the decompression cam and is rotatably fitted through the exhaust cam by the decompression cam shaft.

[0014] Furthermore, a driving rod is provided at the driving end of the centrifugal block, and the decompression cam is provided with a driving hole deviating from the axis of the decompression cam. The driving rod is inserted into the driving hole and is used to drive the decompression cam to rotate through the centrifugal movement and return movement of the centrifugal block.

[0015] The utility model also provides an engine, on which the camshaft decompression mechanism with variable valve timing phase and valve lift as described above is installed.

[0016] The beneficial effects of the utility model: the camshaft decompression mechanism with variable valve timing phase and valve lift of the utility model arranges the decompression mechanism between the timing driven wheel and the intake cam, which can reduce the overall weight of the camshaft, reduce fuel consumption, and have a more compact structure. The width of the chain cavity on the timing driven wheel is narrowed, thereby controlling the overall external dimensions of the engine. The decompression mechanism is combined with the camshaft as a whole, and the assembly is more convenient. The use of the decompression mechanism can ensure that the engine is easier to start. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0018] Figure 1 It is a schematic diagram of the structure of the utility model;

[0019] Figure 2 It is a schematic diagram of the structural section of the utility model;

[0020] Figure 3 It is a top view of the utility model.

[0021] Numbers in the figure: 1. camshaft; 2. exhaust cam; 3. timing driven wheel; 4. bearing; 5. centrifugal block; 6. torsion spring; 7. bushing; 8. centrifugal block shaft; 9. shaft hole; 10. mounting groove; 11. decompression cam; 12. exhaust rocker arm; 13. convex part; 14. low-speed intake cam; 15. high-speed intake cam; 16. driving rod; 17. decompression camshaft; 18. driving hole. DETAILED DESCRIPTION

[0022] Figure 1 It is a structural schematic diagram of the utility model. Figure 2 is a schematic diagram of the structural section. Figure 3It is a top view, as shown in the figure, the camshaft decompression mechanism with variable valve timing and valve lift provided by the utility model comprises a high-speed and low-speed cam group, an exhaust cam 2 and a decompression mechanism arranged on the camshaft 1, the high-speed and low-speed cam group comprises a high-speed intake cam 15 and a low-speed intake cam 14, and the decompression mechanism is arranged between the high-speed and low-speed cam group and the timing driven wheel 3; the decompression mechanism comprises a decompression member arranged beside the exhaust cam 2 of the camshaft 1 and a centrifugal member for driving the decompression member, when the engine is started, the decompression member acts on the exhaust rocker arm 12 to open the exhaust valve, after the engine is started, under the action of the centrifugal member, the decompression member is separated from the exhaust rocker arm 12; the decompression member is separated from the rocker arm means that after the engine is started, the centrifugal member drives the decompression member to rotate when performing centrifugal motion so that it no longer acts on the exhaust rocker arm 12; the camshaft 1 refers to the engine A component in the engine, used to control the opening and closing of the intake valve and exhaust valve in the engine to ensure sufficient intake and exhaust of the cylinder; balancing the internal pressure of the engine means that during the use of the engine, the pressure in the cylinder is too high, the engine displacement and the engine compression ratio gradually increase, and the starting torque required by the engine also gradually increases, which is not conducive to starting. In order to make the engine easier to start, the pressure reduction mechanism must be used to balance the pressure inside the engine; the pressure reduction mechanism generally uses a centrifugal block 5, a spring, etc. in conjunction with a valve rocker arm or a valve stem to balance the pressure inside the engine. The pressure reduction member is arranged next to the camshaft 1 and the exhaust cam 2. The pressure reduction member and the exhaust cam 2 are integrally located between the intake cam and the timing driven wheel, which can reduce the axial length of each shaft in the pressure reduction mechanism, and the machining accuracy requirements of the shaft holes corresponding to the shafts are reduced. The pressure reduction mechanism is easier to achieve the pressure reduction function, such as Figure 3 As shown, if the decompression mechanism is arranged as a whole on the right side of the timing driven wheel 3, the axial length of each shaft required by the decompression mechanism becomes longer. During use, the excessively long axial length is prone to jamming, which is not conducive to the realization of the decompression function. At the same time, the excessively long axial length requires higher processing precision, thereby increasing the processing cost; the high and low speed cam groups act on the intake rocker arm to open the intake valve.

[0023] In this embodiment, the decompression member is a decompression cam 11 that rotates with the exhaust cam 2, and the centrifugal member is a centrifugal block 5. The centrifugal block 5 is driven to contact the decompression cam 11. When the engine is started, the centrifugal block 5 is in an initial position and limits the decompression cam 11 from contacting the exhaust rocker arm 12 to open the exhaust valve. After the engine is started, the centrifugal block 5 drives the decompression cam 11 to rotate and disengage from the exhaust rocker arm 12 through centrifugal force; the initial position of the centrifugal block 5 is that the centrifugal block 5 is placed on the shaft of the camshaft 1.

[0024] In this embodiment, the centrifugal block is provided with a reset component, which applies a pre-tightening force to the centrifugal block, and the pre-tightening force makes the centrifugal block have a tendency to return to the initial position; the centrifugal block 5 is swingably mounted on the camshaft 1 through a centrifugal block shaft 8, and the reset component includes a torsion spring 6, which is sleeved on the centrifugal block shaft 8 to apply a pre-tightening force to the centrifugal block 5; the centrifugal block 5 can be swung, which means that the centrifugal block 5 swings along the radial direction of the camshaft, one end of the torsion spring 6 is fixed at a corresponding position of the camshaft 1, and the other end acts on the centrifugal block 5 to apply a pre-tightening force; when the centrifugal block 5 performs centrifugal motion, the torsion spring 6 is squeezed by the centrifugal block 5 and twisted, and the torsion spring 6 will store elastic energy. After the centrifugal block 5 stops squeezing, the torsion spring 6 will return to the original state through an elastic recovery process and release the stored energy at the same time. In this process, the torsion spring will generate torque or rotational force to reset the centrifugal block 5 to its initial position.

[0025] In this embodiment, the reset assembly also includes a bushing 7 sleeved on the centrifugal block shaft 8, and the torsion spring 6 is sleeved on the centrifugal block shaft 8 through the bushing 7; the centrifugal block shaft 6 is fixed to the set position of the exhaust cam 2 of the camshaft 1, and the centrifugal block 5 is rotatably mounted on the centrifugal block shaft 8 to form a swingable structure; during the use of the engine, the centrifugal block shaft 8 is exposed for a long time, which will cause interference and wear between parts. When the wear reaches a certain extent, the parts must be replaced. The bushing 7 is sleeved on the centrifugal block shaft 8 to protect the centrifugal block shaft, prevent the centrifugal block shaft 8 from contacting other parts, and reduce wear and interference. The bushing 7 can be made of a material with lower hardness and better wear resistance, which can also reduce the wear of the bushing 7 on the centrifugal block shaft 8.

[0026] In this embodiment, the centrifugal block 5 is a large semi-annular shape, one end of which is a driving end for driving the decompression cam 11, and the other end is rotatably mounted on a centrifugal block shaft 8, and the decompression cam 11 is located between the centrifugal block 5 and the exhaust cam 2; the centrifugal block 5 is swingably mounted next to the exhaust cam 2 through the centrifugal block shaft 8, the centrifugal block shaft 8 is cylindrical, and a circular hole conforming to the cross-section of the centrifugal block shaft 8 is opened on the surface of the centrifugal block 5, which is used to install the centrifugal block 5 next to the exhaust cam 2. The centrifugal block 5 can also be arranged next to the exhaust cam 2 by other mechanical connection methods, which will not be repeated here; Figure 2 As shown, the exhaust cam 2 is provided with a centrifugal block shaft hole 9 for installing the centrifugal block shaft 8, and the exhaust cam 2 is provided with a mounting groove 10 for mounting the bushing 7 on the shaft hole 9. The axis of the centrifugal block shaft hole 9 overlaps with the axis of the mounting groove 10. The centrifugal block shaft 8 is pressed into the centrifugal block shaft hole 9 by interference fit to achieve a tight fit with the centrifugal block shaft hole 9 to prevent the connection from falling off or transmitting large torque.

[0027] In this embodiment, the decompression cam 11 is axially extended with a decompression cam shaft 17 and is rotatably fitted through the exhaust cam 2; the decompression cam shaft 17 is cylindrical and is fitted through the exhaust cam 2 through clearance.

[0028] In this embodiment, a driving rod 16 is provided at the driving end of the centrifugal block, and the decompression cam 11 is provided with a driving hole 18 deviating from the axis of the decompression cam 11. The driving rod 16 is penetrated in the driving hole 18, and is used to drive the decompression cam 11 to rotate through the centrifugal movement and return movement of the centrifugal block 5; the driving hole 18 deviates from the axis and is set corresponding to the decompression cam 11, and the driving hole 18 can also be set corresponding to other positions deviated from the decompression cam 11, but the deviation from the axis can make the centrifugal block 5 more effectively drive the decompression cam 11 to rotate around the decompression cam shaft 17 through the driving rod 16 during centrifugal movement and return movement.

[0029] In this embodiment, the exhaust cam 2 is correspondingly provided with an exhaust rocker arm 12, and the exhaust rocker arm 12 can open the exhaust valve by contacting the decompression cam 11. The exhaust rocker arm 12 can be provided with a protrusion 13 at the position where the exhaust rocker arm 12 contacts the decompression cam 11, and the decompression cam 11 controls the exhaust rocker arm 12 to open the exhaust valve by contacting the protrusion 13.

[0030] In this embodiment, the centrifugal block 5 drives the decompression cam 11 to rotate around the decompression cam shaft 17 through the driving rod 16 when the centrifugal block 5 performs centrifugal motion, and the decompression cam 11 completes the balance of the internal pressure of the engine by cooperating with the convex portion 13. The decompression cam 11 has two extreme rotation positions, namely, contacting or not contacting the convex portion 13 on the exhaust rocker arm 12. When the engine is started, the centrifugal block 5 is in the initial position and limits the decompression cam 11 to be in contact with the convex portion 13, thereby controlling the exhaust rocker arm 12 to open the exhaust valve to release the pressure inside the engine. After the engine is started, the centrifugal block 5 performs centrifugal motion, and the centrifugal block 5 drives the decompression cam 11 to rotate around the decompression cam shaft 17 through the driving rod 16 and disengage from the convex portion 13.

[0031] In this embodiment, during the flameout process of the engine, the compression stroke of the engine needs to be driven by the inertia of the flywheel and the crankshaft. When the engine speed is high, the rotational inertia is large, which can drive the piston to compress the air to the highest point to complete the compression stroke. When the engine is about to stop after flameout, the piston performs a compression stroke and the piston moves upward. When the air in the cylinder is compressed to a certain extent, the crankshaft cannot continue to rotate. At this time, the compressed air in the cylinder pushes the piston to start to move downward and drives the crankshaft to reverse. The reverse rotation of the crankshaft will impact the one-way device and cause damage to the one-way device, thereby reducing its service life; during the flameout process of the engine, as the speed decreases, the centrifugal block 5 is reset by the reset assembly, and the centrifugal block 5 drives the decompression cam 11 to rotate around the decompression camshaft 17 through the drive rod 16 and contacts the convex portion 13 of the exhaust rocker arm 12, thereby controlling the exhaust rocker arm 12 to open the exhaust valve. When the engine is about to stop after flameout, the compressed air generated by the compression stroke of the piston can be discharged in time to avoid the impact of the crankshaft reversal on the one-way device.

[0032] In this embodiment, bearings 4 are provided at both ends of the camshaft 1. Figure 3 As shown, the bearing 4 close to the centrifugal block 5 is used to limit the centrifugal block 5, and the camshaft 1 is provided with a timing driven wheel 3 next to the bearing 4 close to the centrifugal block 5; Figure 3 As shown, the bearing 4 close to the centrifugal block 5 is located on the right side of the centrifugal block 5, and the timing driven wheel 3 is located at the rightmost end of the camshaft 1. The bearing 4 can not only limit the centrifugal block 5, but also reduce the friction coefficient during its movement and ensure its rotation accuracy. The bearing 4 is generally a rolling bearing, and other types of bearings can also be used to axially limit the decompression mechanism, which will not be repeated here.

[0033] In this embodiment, the camshaft 1 is also provided with a high-speed and low-speed cam group, which includes a low-speed intake cam 14 and a high-speed intake cam 15. The low-speed intake cam 14 and the high-speed intake cam 15 act on the intake rocker arm to open the intake valve. Since the profile of the high-speed intake cam includes the profile of the low-speed intake cam, and the cam lobe angle and the maximum cam lift are different, variable valve timing and valve lift are achieved; Figure 3 As shown, a bearing 4 is provided at the leftmost end of the camshaft 1, and a low-speed intake cam 14 and a high-speed intake cam 15 are provided between the camshaft 1 and the exhaust cam 2. The variable valve timing and valve lift are realized by switching the low-speed intake cam 14 and the high-speed intake cam 15 to drive the intake valve.

[0034] In this embodiment, an engine is also provided, characterized in that: the engine is equipped with the above-mentioned camshaft decompression mechanism with variable valve timing and valve lift, and the variable valve timing and valve lift can be realized by switching the low-speed intake cam 14 and the high-speed intake cam 15 to drive the intake valve. However, due to the increase in the number of cams, the space on the camshaft 1 is very limited. Figure 3 As shown, a decompression mechanism composed of a decompression member and a centrifugal member is arranged between the exhaust cam 2 and the timing driven wheel 3, and a decompression mechanism can also be arranged between the high-speed and low-speed cam groups and the exhaust cam 2. However, under the premise of realizing variable valve timing phase and valve lift, the space for arranging the decompression mechanism on the camshaft shaft is limited, and the space between the high-speed and low-speed cam groups and the exhaust cam 2 is generally a fixed design size, and the space is very limited. Compared with the decompression mechanism between the high-speed and low-speed cam groups and the exhaust cam 2, the decompression mechanism between the exhaust cam 2 and the timing driven wheel 3 is more reasonably used in space. Both arrangements can ensure that the decompression mechanism can be located between the timing driven wheel 3 and the high-speed and low-speed cam groups, which can reduce the overall weight of the camshaft and narrow the width of the chain cavity on the timing driven wheel, thereby controlling the overall external dimensions of the engine. After the bearing is pressed, the decompression mechanism and the camshaft become a whole, which is easy to assemble.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A camshaft decompression mechanism with variable valve timing and valve lift, characterized in that: It includes a high-speed and low-speed cam group, an exhaust cam and a decompression mechanism arranged on a camshaft. The high-speed and low-speed cam group includes a high-speed intake cam and a low-speed intake cam. The decompression mechanism is arranged between the high-speed and low-speed cam group and the timing driven wheel.

2. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 1, characterized in that: The decompression mechanism includes a decompression member arranged next to the exhaust cam of the camshaft and a centrifugal member for driving the decompression member. When the engine is started, the decompression member acts on the exhaust rocker arm to open the exhaust valve. After the engine is started, under the action of the centrifugal member, the decompression member is separated from the exhaust rocker arm.

3. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 2, characterized in that: The decompression member is a decompression cam that rotates with the exhaust cam, and the centrifugal member is a centrifugal block. The centrifugal block is driven to contact the decompression cam. When the engine is started, the centrifugal block is in an initial position and limits the decompression cam to a position that contacts the exhaust rocker arm and opens the exhaust valve. After the engine is started, the centrifugal block drives the decompression cam to rotate and disengage from the exhaust rocker arm through centrifugal force.

4. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 3, characterized in that: The centrifugal block is provided with a reset component, and the reset component applies a pre-tightening force to the centrifugal block, and the pre-tightening force makes the centrifugal block have a tendency to return to an initial position.

5. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 4, characterized in that: The centrifugal block is swingably mounted on the camshaft via a centrifugal block shaft, and the reset assembly comprises a torsion spring, which is sleeved on the centrifugal block shaft to apply a pre-tightening force to the centrifugal block.

6. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 5, characterized in that: The reset assembly also includes a sleeve sleeved on the centrifugal block shaft, and the torsion spring is sleeved on the centrifugal block shaft through the sleeve; the centrifugal block shaft is fixed to the set position of the exhaust cam of the camshaft, and the centrifugal block is rotatably mounted on the centrifugal block shaft to form a swingable structure.

7. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 3, characterized in that: The centrifugal block is in the shape of a large semi-ring, one end of which is a driving end for driving the decompression cam, and the other end is rotatably fitted with a centrifugal block shaft, and the decompression cam is located between the centrifugal block and the exhaust cam.

8. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 3, characterized in that: A decompression cam shaft is axially extended from the decompression cam and is rotatably fitted through the exhaust cam by the decompression cam shaft.

9. The camshaft decompression mechanism with variable valve timing and valve lift according to claim 3, characterized in that: A driving rod is provided at the driving end of the centrifugal block, and the decompression cam is provided with a driving hole deviating from the axis of the decompression cam. The driving rod is inserted into the driving hole and is used to drive the decompression cam to rotate through the centrifugal motion and return motion of the centrifugal block.

10. An engine, characterized in that: The engine is equipped with a camshaft decompression mechanism with variable valve timing and valve lift as described in any one of claims 1-9.

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