Flywheel end signal acquisition device and cam top dead center positioning method

Abstract

The invention discloses a flywheel end signal acquisition device and a cam top dead center positioning method. The acquisition device comprises an engine flywheel; mounting a bracket; the rotating speed sensor is mounted on the mounting bracket; the acquisition device further comprises an auxiliary simulation block used for assisting the rotating speed sensor to generate sine wave simulation signals, any longitudinal section of the circumferential face of the auxiliary simulation block is in a curve-shaped protrusion shape, the highest point of the protrusion is a detection point, and when the auxiliary simulation block is fixed to the flywheel, the projection of the detection point on the circumferential face of the flywheel coincides with the protruding point on the flywheel. A track formed by the detection points after the flywheel rotates is a detection track, and the projection of the detection area of the rotating speed sensor on the flywheel is always on the projection of the detection track on the flywheel. The device can stably and quickly install the rotating speed sensor and can accurately position the rotating speed sensor.

Description

Technical Field

[0001] The invention belongs to the field of engine detection equipment, and in particular relates to a flywheel end signal acquisition device and a cam top dead center positioning method. Background Art

[0002] In view of the requirements of future engine assembly durability test verification, such as gasoline, diesel, natural gas, hydrogen, etc., during the durability test, it is necessary to monitor the changes of different parameters on the engine for the crankshaft angle, such as the cam top dead center position, internal valve mechanism force, valve mechanism displacement, etc.; the traditional method is to add a cylinder pressure sensor on the top of the combustion chamber; because the cylinder pressure sensor is a relatively sensitive and fragile measuring device, it is easy to be damaged under the influence of temperature, liquid and vibration; in the traditional durability test verification, if the cylinder pressure sensor is not installed, it is necessary to monitor the engine for the changes of the crankshaft angle, which cannot be achieved. Summary of the invention

[0003] The object of the present invention is to provide a method for determining a cam top point positioning based on a flywheel end signal acquisition device which is simple to operate and accurate.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a flywheel-end signal acquisition device, which includes: an engine flywheel; a mounting bracket; a speed sensor, which is installed on the mounting bracket; the acquisition device also includes an auxiliary simulation block for assisting the speed sensor to generate a sinusoidal wave simulation signal, any longitudinal section of the circumference of the auxiliary simulation block is a curved protrusion, and the highest point of the protrusion is a detection point. When the auxiliary simulation block is fixed to the flywheel, the projection of the detection point on the circumference of the flywheel coincides with the convex point on the flywheel, and the trajectory formed by the detection point after the flywheel rotates is the detection trajectory, and the projection of the detection area of ​​the speed sensor on the flywheel is always on the projection of the detection trajectory on the flywheel.

[0005] In another embodiment, any longitudinal section of the peripheral surface of the auxiliary simulation block is in the shape of a half-wave sine curve or a semicircle.

[0006] In another embodiment, a groove is formed on the convex point of the flywheel, and a positioning convex block matching the groove is provided at the projection position of the detection point on the lower end surface of the auxiliary simulation block, and the positioning convex block is arranged in the groove.

[0007] In another embodiment, the mounting bracket includes a first positioning block, a second positioning block with its left end inserted into the first positioning block, an elastic column for ensuring that the second positioning block always has a tendency to move toward the first positioning block, a first clamping block formed on the right end of the upper end surface of the first positioning block, a second clamping block formed on the left end of the upper end surface of the second positioning block, and a third positioning block formed on the right end of the lower end surface of the first positioning block, and the speed sensor is fixed on the third positioning block. When the second positioning block contracts into the first positioning block, the first clamping block and the second clamping block move toward each other to clamp the engine housing; when the second positioning block moves outward from the first positioning block, the first clamping block and the second clamping block move away from each other to loosen the engine housing.

[0008] In another embodiment, an installation groove is formed in the first positioning block, the second positioning block is arranged in the installation groove, a first limit block is formed on the right end of the installation groove, and a second limit block is formed on the front and rear side surfaces of the second positioning block, and an elastic column for ensuring that the second positioning block always has a tendency to move toward the first positioning block is arranged between the first limit block and the second limit block.

[0009] In another embodiment, a guide groove extending upward is formed on the lower end surface of the left end portion of the second positioning block, a tightening guide surface is formed at an upper position of the left inner wall of the guide groove, and a loosening guide surface is formed at a lower position of the right inner wall of the guide groove, the mounting bracket also includes a locking bolt threadedly connected to the first positioning block and partially inserted into the guide groove, the screw head of the locking bolt is located at the lower end of the locking bolt, a first frusto-conical boss is provided on the upper end of the locking bolt, the outer peripheral surface of the first boss matches the tightening guide surface to form a first wedge-shaped surface, and the center of the locking bolt The part is provided with an inverted frustum-shaped second boss, the outer peripheral surface of the second boss matches the loosening guide surface to form a second wedge surface, when the locking bolt is tightened, the second wedge surface separates from the loosening guide surface, the first wedge surface squeezes the tightening guide surface, so that the second positioning block moves into the first positioning block, the first clamping block and the second clamping block move toward each other to clamp the engine housing, when the locking bolt is loosened, the first wedge surface separates from the tightening guide surface, the second wedge surface squeezes the loosening guide surface, so that the second positioning block moves out of the first positioning block, the first clamping block and the second clamping block move away from each other to loosen the engine housing. The speed sensor can collect the signal of the top dead center of the flywheel and the signal is in the form of a sine wave, which is convenient for signal processing and can effectively eliminate the interference of burrs on the flywheel, greatly simplifying the detection method and structure and reducing the detection cost.

[0010] In another implementation manner, the third positioning block is provided with a mounting hole extending in the left-right direction, and the rotation speed sensor is fixedly inserted into the mounting hole.

[0011] In another embodiment, a shock absorbing ring is provided on the inner circle of the mounting hole, and the rotation speed sensor is fixedly inserted into the shock absorbing ring.

[0012] The present invention also provides a method for positioning a cam top dead center, which comprises the following steps:

[0013] a. Install the flywheel end signal acquisition device according to any one of claims 1-8 on the engine housing;

[0014] b. After the speed sensor and half-wave sine curve sensing components are installed, the engine is reversed and the speed is controlled at 1000-1800rpm;

[0015] c. Graphically check whether it is a square wave signal through the acquisition device. If it is not a square wave signal, the signal collected by the half-wave sine component in the combustion analyzer is corrected on the rising and falling edges and the signal burrs are removed through the OTTO algorithm. The acquisition device needs to be adjusted to make the signal a square wave signal;

[0016] d. Based on the speed ratio of the square wave signal flywheel and cam, calculate the top dead center of the cam.

[0017] In another implementation manner, when the measuring harness of the rotation speed sensor is led out of the engine, it bypasses high-speed rotating and high-temperature components, and the harness is wrapped with twisted pair wires and a metal sheath to prevent electromagnetic interference from affecting signal measurement.

[0018] Due to the application of the above technical scheme, the present invention has the following advantages compared with the prior art: the device can stably and quickly install the speed sensor, and can accurately locate it; the positioning method can not only accurately find the top dead center, but also timely monitor and collect the values ​​of other signals relative to the crankshaft angle in the engine durability test, which is convenient for experimental analysis. At the same time, in the case of signal acquisition, if there is electromagnetic interference to generate torque or distortion of the signal, there is no need for filtering and deburring, and the system can activate the OTTO algorithm to correct the signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the installation structure of the present invention;

[0020] Figure 2 A perspective view of the present invention;

[0021] Figure 3 A top view of the present invention;

[0022] Figure 4 for Figure 3 AA section view;

[0023] Figure 5 for Figure 3 BB cross-sectional view;

[0024] Figure 6 for Figure 4 Enlarged view at center C;

[0025] Figure 7 The figure is a flow chart of the positioning method. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings.

[0027] See also Figure 1-6 As shown, the flywheel end signal acquisition device includes: an engine flywheel 4, a mounting bracket 1, a speed sensor 3, and an auxiliary simulation block 2. The speed sensor 3 is mounted on the mounting bracket 1.

[0028] The auxiliary simulation block 2 is used to assist the speed sensor 3 in generating a sinusoidal wave simulation signal. Any longitudinal section of the peripheral surface of the auxiliary simulation block 2 is a curved convexity, and the highest point of the convexity is the detection point. When the auxiliary simulation block 2 is fixed to the flywheel, the projection of the detection point on the peripheral surface of the flywheel coincides with the upper dead center of the flywheel. The trajectory formed by the detection point after the flywheel rotates is the detection trajectory. The projection of the detection area of ​​the speed sensor 3 on the flywheel is always on the projection of the detection trajectory on the flywheel. Any longitudinal section of the peripheral surface of the auxiliary simulation block 2 is a half-wave sine curve or a semicircle. In order to facilitate signal collection and input, a half-wave sine curve is the best. In order to facilitate positioning, a groove 41 is formed on the upper dead center of the flywheel, and a positioning convex block 21 matching the groove 41 is provided at the position of the projection of the detection point on the lower end surface of the auxiliary simulation block 2, and the positioning convex block 21 is arranged in the groove 41.

[0029] In order to improve the convenience of installation and clamping of the mounting bracket 1, the mounting bracket 1 includes a first positioning block 11, a second positioning block 12 with a left end inserted in the first positioning block 11, an elastic column 13 used to make the second positioning block 12 always have a tendency to move toward the first positioning block 11, a first clamping block 14 formed on the right end of the upper end surface of the first positioning block 11, a second clamping block 15 formed on the left end of the upper end surface of the second positioning block 12, and a third positioning block 16 formed on the right end of the lower end surface of the first positioning block 11. The right end of the upper end surface of the second positioning block 12 has an alignment surface 116 flush with the upper end surface of the first positioning block 11, and the speed sensor 3 is fixed on the third positioning block 16. When the second positioning block 12 shrinks into the first positioning block 11, the first clamping block 14 and the second clamping block 15 move toward each other to clamp the engine housing 5; when the second positioning block 12 moves out of the first positioning block 11, the first clamping block 14 and the second clamping block 15 move away from each other to release the engine housing 5. An installation groove 17 is formed in the first positioning block 11, and the second positioning block 12 is arranged in the installation groove 17. A first limit block 18 is formed on the right end of the installation groove 17, and a second limit block 19 is formed on the front and rear side surfaces of the second positioning block 12. An elastic column 13 for ensuring that the second positioning block 12 always has a tendency to move toward the first positioning block 11 is arranged between the first limit block 18 and the second limit block 19. A guide groove 10 extending upward is provided on the lower end surface of the left end portion of the second positioning block 12, a tightening guide surface 111 is formed at the upper position of the left inner wall of the guide groove 10, and a loosening guide surface 110 is formed at the lower position of the right inner wall of the guide groove 10. The mounting bracket 1 also includes a locking bolt 117 which is threadedly connected to the first positioning block 11 and partially penetrates into the guide groove 10, the screw head of the locking bolt 117 is located at the lower end portion of the locking bolt 117, and a first frustum-shaped boss 112 is provided on the upper end portion of the locking bolt 117, the outer peripheral surface of the first boss 112 matches the tightening guide surface 111 to form a first wedge-shaped surface, and an inverted cone-shaped boss 112 is provided on the middle portion of the locking bolt 117. The second boss 113 is in the form of a platform, and the outer peripheral surface of the second boss 113 matches with the loosening guide surface 110 to form a second wedge surface. When the locking bolt 117 is tightened, the second wedge surface separates from the loosening guide surface 110, and the first wedge surface squeezes the tightening guide surface 111, so that the second positioning block 12 moves into the first positioning block 11, and the first clamping block 14 and the second clamping block 15 move toward each other to clamp the engine housing 5. When the locking bolt 117 is loosened, the first wedge surface separates from the tightening guide surface 111, and the second wedge surface squeezes the loosening guide surface 110, so that the second positioning block 12 moves out of the first positioning block 11, and the first clamping block 14 and the second clamping block 15 move away from each other to loosen the engine housing 5. The speed sensor 3 can collect the signal of the top dead center of the flywheel and the signal is in the form of a sine wave, which is convenient for signal processing and can effectively eliminate the interference of burrs on the flywheel, greatly simplifying the detection method and structure and reducing the detection cost.

[0030] The third positioning block 16 is provided with a mounting hole 114 extending in the left-right direction, and the speed sensor 3 is fixedly installed in the mounting hole 114. A damping ring 115 is provided in the inner circle of the mounting hole 114, and the speed sensor 3 is fixedly installed in the damping ring 115.

[0031] See also Figure 7 As shown, the positioning method of the cam top dead point includes the following steps:

[0032] a. Install the flywheel end signal acquisition device according to any one of claims 1-8 on the engine housing;

[0033] b. After the speed sensor and half-wave sine curve sensing components are installed, the engine is reversed and the speed is controlled at 1000-1800rpm;

[0034] c. Graphically check whether it is a square wave signal through the acquisition device. If it is not a square wave signal, the signal collected by the half-wave sine component in the combustion analyzer is corrected and the signal burrs are removed through the OTTO algorithm on the rising and falling edges. The acquisition device needs to be adjusted to make the signal a square wave signal. The OTTO cycle model is a cycle performance calculation method based on the actual engine operation and the finite time thermodynamics theory analysis model. Based on the model algorithm (the convex point signal at the flywheel end), the top point on the crankshaft or camshaft is finally determined; (For details, see the paper description of the National Natural Science Foundation (51779262) and the Wuhan University of Technology Graduate Education Innovation Fund (CX2020038));

[0035] d. Calculate the top dead center of the cam based on the speed ratio of the square wave signal flywheel and the cam;

[0036] When the measurement harness of the speed sensor is led out of the engine, it bypasses high-speed rotating and high-temperature components. At the same time, the harness is wrapped with twisted pair wires and a metal sheath to prevent electromagnetic interference from affecting the signal measurement.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A flywheel end signal acquisition device, comprising: Engine flywheel; mounting bracket; A speed sensor, which is installed on the mounting bracket; characterized in that: the acquisition device also includes an auxiliary simulation block for assisting the speed sensor to generate a sinusoidal wave simulation signal, any longitudinal section of the circumference of the auxiliary simulation block is a curved protrusion, and the highest point of the protrusion is a detection point. When the auxiliary simulation block is fixed to the flywheel, the projection of the detection point on the circumference of the flywheel coincides with the convex point on the flywheel, and the trajectory formed by the detection point after the flywheel rotates is the detection trajectory, and the projection of the detection area of ​​the speed sensor on the flywheel is always on the projection of the detection trajectory on the flywheel.

2. The flywheel end signal acquisition device according to claim 1, characterized in that: Any longitudinal section of the peripheral surface of the auxiliary simulation block is in the shape of a half-wave sine curve or a semicircle.

3. The flywheel end signal acquisition device according to claim 1, characterized in that: A groove is formed on the convex point of the flywheel, and a positioning convex block matching the groove is provided at the projection position of the detection point on the lower end surface of the auxiliary simulation block, and the positioning convex block is arranged in the groove.

4. The flywheel end signal acquisition device according to claim 1, characterized in that: The mounting bracket includes a first positioning block, a second positioning block with its left end inserted into the first positioning block, an elastic column used to make the second positioning block always have a tendency to move toward the first positioning block, a first clamping block formed on the right end of the upper end surface of the first positioning block, a second clamping block formed on the left end of the upper end surface of the second positioning block, and a third positioning block formed on the right end of the lower end surface of the first positioning block. The speed sensor is fixed on the third positioning block. When the second positioning block shrinks into the first positioning block, the first clamping block and the second clamping block move toward each other to clamp the engine housing; when the second positioning block moves out of the first positioning block, the first clamping block and the second clamping block move away from each other to loosen the engine housing.

5. The flywheel end signal acquisition device according to claim 4, characterized in that: An installation groove is formed in the first positioning block, the second positioning block is arranged in the installation groove, a first limit block is formed on the right end of the installation groove, and a second limit block is formed on the front and rear side surfaces of the second positioning block. An elastic column for ensuring that the second positioning block always has a tendency to move toward the first positioning block is arranged between the first limit block and the second limit block.

6. The flywheel end signal acquisition device according to claim 4, characterized in that: A guide groove extending upward is formed on the lower end surface of the left end portion of the second positioning block, a tightening guide surface is formed at an upper position of the left inner wall of the guide groove, and a loosening guide surface is formed at a lower position of the right inner wall of the guide groove, the mounting bracket also includes a locking bolt threadedly connected to the first positioning block and partially inserted into the guide groove, the screw head of the locking bolt is located at the lower end portion of the locking bolt, a first truncated cone-shaped boss is provided on the upper end portion of the locking bolt, the outer peripheral surface of the first boss matches the tightening guide surface to form a first wedge-shaped surface, and a locking bolt is provided on the middle portion of the locking bolt The second boss is in the shape of an inverted cone, and the outer peripheral surface of the second boss matches the loosening guide surface to form a second wedge surface. When the locking bolt is tightened, the second wedge surface separates from the loosening guide surface, and the first wedge surface squeezes the tightening guide surface, so that the second positioning block moves toward the first positioning block, and the first clamping block and the second clamping block move toward each other to clamp the engine housing. When the locking bolt is loosened, the first wedge surface separates from the tightening guide surface, and the second wedge surface squeezes the loosening guide surface, so that the second positioning block moves outward from the first positioning block, and the first clamping block and the second clamping block move away from each other to loosen the engine housing.

7. The flywheel end signal acquisition device according to claim 4, characterized in that: The third positioning block is provided with a mounting hole extending in the left-right direction, and the rotation speed sensor is fixedly arranged in the mounting hole.

8. The flywheel end signal acquisition device according to claim 1, characterized in that: A shock absorbing ring is arranged in the inner circle of the mounting hole, and the rotation speed sensor is fixedly arranged in the shock absorbing ring.

9. A method for positioning a cam top dead center, characterized in that: It includes the following steps: a. Install the flywheel end signal acquisition device according to any one of claims 1-8 on the engine housing; b. After the speed sensor and half-wave sine curve sensing components are installed, the engine is reversed and the speed is controlled at 1000-1800rpm; c. Graphically check whether it is a square wave signal through the acquisition device. If it is not a square wave signal, the signal collected by the half-wave sine component in the combustion analyzer is corrected on the rising and falling edges and the signal burrs are removed through the OTTO algorithm. The acquisition device needs to be adjusted to make the signal a square wave signal; d. Calculate the top dead center of the cam based on the square wave signal, the speed ratio of the flywheel and the corresponding cam.

10. The positioning method according to claim 9, characterized in that: When the measuring wire harness of the rotation speed sensor is led out of the engine, it bypasses high-speed rotating and high-temperature components, and the wire harness is wrapped with twisted pair wires and a metal sheath to prevent electromagnetic interference from affecting signal measurement.

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