Device for measuring minimum dynamic gap between piston and valve

Abstract

The utility model discloses a device for measuring the minimum dynamic gap between a piston and an air valve, the piston is arranged below the air valve, the upper end of the piston is provided with threaded holes, the threaded holes comprise a first threaded hole, the first threaded hole is arranged below the air valve, a first bolt is arranged in the first threaded hole, and the top end of the first bolt extends out of the first threaded hole; the device for measuring the minimum dynamic gap between the piston and the air valve is simple in structure and convenient to measure.

Description

Technical Field

[0001] The utility model belongs to the field of measurement technology, and specifically relates to a device for measuring the minimum dynamic clearance between a piston and a valve. Background Art

[0002] The natural gas engine is an important internal combustion engine. Correctly adjusting the clearance between the valve and the piston can ensure the normal operation of the engine and improve the performance and durability of the engine. Therefore, the measurement of the piston and valve clearance is of great significance to improving the performance of the natural gas engine.

[0003] Pistons and valves are the core of the engine. Once problems occur, the normal use of the vehicle will be affected. As the working intensity of the engine increases, the working environment of the components gradually deteriorates. The engine generates a lot of heat during operation, and the components expand fully due to the heat. The gap between the valve and the piston will also become smaller due to the temperature. In addition, since both the valve and the piston are moving parts, the gap between the two is difficult to measure with current technology. If the gap value between the valve and the piston cannot be fully grasped, it will directly cause the valve and the piston to collide in serious cases.

[0004] The utility model patent with announcement number CN203908467U was published on October 29, 2014. It is named as a valve stem and guide tube clearance detection device, which includes a dial indicator, a machine base, a clamping block, a bracket and a cylinder arranged in pairs on the machine base. The piston rods of the cylinders are provided with clamping blocks. The two clamping blocks are opposite and cooperate to clamp the guide tube. The lower end of the clamping block is slidably connected to the machine base. The base between the two clamping blocks is provided with a positioning hole. The bracket is fixed on the machine base, the dial indicator is connected to the bracket, and the measuring head of the dial indicator is against the edge of the valve disc. The valve stem and guide tube clearance detection device cannot realize the clearance measurement between the piston and the valve. Utility Model Content

[0005] The utility model aims to provide a device for measuring the minimum dynamic clearance between a piston and a valve with a simple structure and convenient measurement in view of the deficiencies in the prior art.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] The device for measuring the minimum dynamic clearance between a piston and a valve comprises: the piston is arranged below the valve, the upper end of the piston is provided with a threaded hole, the threaded hole comprises a first threaded hole, the first threaded hole is arranged below the valve, a first bolt is arranged in the first threaded hole, and the top end of the first bolt protrudes from the first threaded hole.

[0008] The threaded holes also include second threaded holes, which are evenly distributed. Second bolts are connected to the second threaded holes, and top ends of the second bolts extend out of the second threaded holes.

[0009] A through hole is provided in the middle of the first bolt, and the through hole passes through the first bolt.

[0010] The upper end of the piston is provided with a groove, the groove is located directly below the valve, and the first threaded hole is provided on the groove.

[0011] A slot is provided at the upper end of the first bolt, and a chamfer is provided at the bottom end of the first bolt.

[0012] The first bolt and the second bolt are made of copper.

[0013] The first bolt and the second bolt are located on the same circumference.

[0014] A cavity is arranged in the middle of the piston.

[0015] The technical effect of the utility model is as follows: by adopting the device for measuring the minimum dynamic clearance between a piston and a valve of the utility model, a bolt is assembled on the piston, the top of the bolt is arranged to protrude from the upper end of the piston, and the deformation amount of the bolt under pressure is measured to realize the dynamic clearance measurement between the valve and the piston, and a through hole is reserved in the bolt to ensure that the gas at the bottom of the bolt can be discharged when the bolt is pressed downward to avoid the gas hindering the downward movement of the bolt, so that protective measures can be taken according to the measurement results to avoid the collision between the valve and the piston, which is beneficial to ensure the normal operation of the engine, improve reliability and durability, and provide guarantee for the normal driving of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] This specification includes the following drawings, which show the following contents:

[0017] Figure 1 It is a three-dimensional schematic diagram of a device for measuring the minimum dynamic clearance between a piston and a valve of the utility model;

[0018] Figure 2 It is a top view of the minimum dynamic clearance measuring device between a piston and a valve of the utility model;

[0019] Figure 3 yes Figure 2 Section BB sectional view;

[0020] Figure 4 It is a cross-sectional view of the bolt of the utility model.

[0021] The markings in the figure are: 1. piston; 2. intake valve; 3. exhaust valve; 4. first threaded hole; 5. second threaded hole; 6. first bolt; 7. second bolt; 8. through hole; 9. slot; 10. chamfer; 11. cavity; 12. groove. DETAILED DESCRIPTION

[0022] The specific implementation methods of the utility model are further explained in detail below with reference to the accompanying drawings through the description of embodiments, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention and to facilitate their implementation.

[0023] like Figures 1 to 4 As shown, the piston and valve minimum dynamic clearance measuring device, the piston 1 is arranged below the valve, the upper end of the piston 1 is provided with a threaded hole, the threaded hole includes a first threaded hole 4, the first threaded hole 4 is located below the valve, a first bolt 6 is provided in the first threaded hole 4, and the top end of the first bolt 6 extends out of the first threaded hole 4.

[0024] Threaded holes are machined at the top of the piston 1 corresponding to the intake valve 2 and the outlet valve 3, and bolts are matched with the threaded holes, and the bolts are assembled on the piston 1. The bolts protrude from the mounting surface of the piston 1, which can avoid collision damage caused by contact between the piston 1 and the valve during the measurement process, which is beneficial to reducing costs. The height of the bolt protruding from the mounting surface of the piston 1 must be greater than the minimum cold dynamic clearance and compression clearance calculated by the design of the corresponding part to ensure that the movement of the valve can contact and press down the bolt. The measurement principle is: through the movement of the valve and piston 1, the valve and the bolt are in contact, so that the bolt moves down or deforms, and the minimum dynamic clearance between the piston 1 and the valve is obtained by measuring the deformation of the bolt before and after the measurement.

[0025] like Figures 1 to 3 As shown, the threaded hole also includes a second threaded hole 5, which is evenly distributed. A second bolt 7 is connected in the second threaded hole 5, and the top of the second bolt 7 extends out of the second threaded hole 5. The piston 1 is evenly distributed with four threaded holes on a circle with a diameter of 95mm. The angles of a=51° and b=39° are respectively made on both sides of a second threaded hole 5 to determine the threaded hole of the outlet valve 3 and the threaded hole of the intake valve 2, so as to achieve the correspondence between the outlet valve 3 and the intake valve 2 and the first bolt 6. All threaded holes and bolts have the same specifications, with a thread specification of M5X0.8, a thread length of 5mm, a threaded hole depth of 7.5mm, and a bolt length of =8mm. The above-mentioned evenly distributed second bolts 7 can measure the gap between the piston 1 and the cylinder head, and the measurement can be carried out synchronously with the piston 1 and the valve clearance measurement process, reducing the measurement steps, avoiding repeated measurements, achieving the effect of improving the measurement efficiency, and ensuring the uniformity of the measurement conditions, and the measurement data is more accurate.

[0026] like Figure 4 As shown, a through hole 8 is provided in the middle of the first bolt 6, and the through hole 8 passes through the first bolt 6. The through hole 8 is reserved in the middle of the bolt, and the diameter is 2 mm. The purpose is to allow the gas at the bottom of the bolt to be discharged when the bolt is pushed down, so as to avoid the gas at this part from being compressed and expanding to hinder the downward movement or deformation process of the bolt.

[0027] The upper end of the piston 1 is provided with a groove 12, which is located just below the valve, and the first threaded hole 4 is provided on the groove 12. Since the valve is a moving part, the groove 12 is provided on the piston 1, and the size of the groove 12 is adapted to the size of the bottom end of the valve, so that the relative movement of the valve and the piston 1 has a certain margin space to avoid the two being too close to each other and causing damage due to excessive collision force.

[0028] like Figure 4 As shown, a slot 9 is provided at the upper end of the first bolt 6, and a chamfer 10 is provided at the bottom end of the first bolt 6. The slot 9 has a depth and a width of 1 mm, and the chamfer 10 is provided at the bottom of the bolt to facilitate alignment of the bolt with the threaded hole and reduce the difficulty of installation.

[0029] The first bolt 6 and the second bolt 7 are made of copper. The copper bolts are more easily deformed by pressure, so it is convenient to compare and obtain the height values ​​of the bolts protruding from the piston 1 before and after the measurement.

[0030] like Figure 2 As shown, the first bolt 6 and the second bolt 7 are located on the same circumference. In the above structure, the bolts used to measure the clearance between the piston 1 and the cylinder head and the bolts used to measure the clearance between the piston 1 and the valve are located on the same circumference, the position variable is controlled, and the measurement reliability of the two clearances is higher.

[0031] like Figure 1 As shown, a cavity 11 is provided in the middle of the piston 1. A cavity 11 is designed on the top of the piston 1 to promote the tumbling flow of the gas in the cylinder during the compression stroke, which is beneficial to increase the fuel combustion speed and ensure full combustion.

[0032] In static state, the clearance between piston 1 and valve and cylinder head can be measured by lead pressing method, that is, use lead wire of suitable size to ensure that valve and cylinder head can be pressed, arrange it at the measuring point of piston 1, install the cylinder head, adjust the valve clearance and then manually turn the wheel, then disassemble the cylinder head and measure the thickness of lead wire.

[0033] Test method: The test is divided into hot dynamic test and cold dynamic test. Hot dynamic test means that the engine is ignited to allow the parts to fully expand due to heat. Cold dynamic test means that the engine is not ignited, the oil temperature and the outlet water temperature are within the normal temperature range to avoid the expansion of parts due to heat. To ensure the reliability of the measurement data, hot dynamic test and cold dynamic test must be carried out on the same engine. Since the cold dynamic test conditions are difficult to control, hot dynamic test is recommended.

[0034] Thermal dynamic test steps:

[0035] Start the engine, and after normal warm-up, conduct external characteristic tests to confirm that the performance meets the requirements. According to the test condition table, conduct tests continuously under the two conditions of ignition and reverse drag. Among them, the first step of the calibration point condition must ensure that the oil temperature and the water outlet temperature (90℃~95℃) are stable and continue to run for 15 minutes. The second and third steps of the condition conversion process require rapid conversion from the ignition condition to the reverse drag condition, and the oil temperature ≥95℃.

[0036] Cold dynamic test steps:

[0037] After the engine is on the test bench, follow step 4 in the test condition table and quickly reverse the engine for 0.5 minutes to ensure that the oil temperature and water outlet temperature are within the normal temperature range to avoid thermal expansion of components. After the test is completed, remove the engine from the test bench to inspect the data.

[0038]

[0039] Table 1 Test conditions

[0040] Minimum dynamic gap data measurement:

[0041] For engines with 6 cylinders, at least 3 cylinders should be processed and measured, and for engines with less than 6 cylinders, at least 2 cylinders should be processed and measured. After completing the above test steps, disassemble the engine, measure the valve clearance, and measure the height of the bolt protruding from the mounting surface after the test (if the pin is loose, the data of this measurement point is invalid), and obtain the minimum value of the measured data, which is the actual measured dynamic minimum clearance at this position. According to the measurement conditions and combined with the evaluation standards, the values ​​measured in the test are compared to determine whether the minimum dynamic clearance between piston 1 and the valve meets the requirements.

[0042]

[0043] Table 2 Measurement evaluation criteria and results

[0044] The device for measuring the minimum dynamic clearance between a piston and a valve is provided by assembling a bolt on a piston 1, setting the top of the bolt protruding from the upper end of the piston 1, and measuring the deformation amount of the bolt under pressure to achieve the dynamic clearance measurement between the valve and the piston 1. A through hole 8 is reserved in the bolt to ensure that the gas at the bottom of the bolt can be discharged when the bolt is pressed downward to avoid the gas hindering the downward movement of the bolt. Therefore, protective measures can be taken according to the measurement results to avoid the collision between the valve and the piston 1, which is beneficial to ensure the normal operation of the engine, improve reliability and durability, and provide guarantee for the normal driving of the vehicle.

[0045] The above is an exemplary description of the utility model in conjunction with the accompanying drawings. Obviously, the specific implementation of the utility model is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the utility model; or the above concept and technical solution of the utility model are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A device for measuring the minimum dynamic clearance between a piston and a valve, characterized in that: The piston (1) is arranged below the valve. A threaded hole is arranged at the upper end of the piston (1). The threaded hole comprises a first threaded hole (4). The first threaded hole (4) is arranged below the valve. A first bolt (6) is arranged in the first threaded hole (4). The top end of the first bolt (6) protrudes out of the first threaded hole (4).

2. The device for measuring the minimum dynamic clearance between a piston and a valve according to claim 1, characterized in that: The threaded holes also include second threaded holes (5), the second threaded holes (5) are evenly distributed, second bolts (7) are connected inside the second threaded holes (5), and the top ends of the second bolts (7) extend out of the second threaded holes (5).

3. The device for measuring the minimum dynamic clearance between a piston and a valve according to claim 1 or 2, characterized in that: A through hole (8) is provided in the middle of the first bolt (6), and the through hole (8) passes through the first bolt (6).

4. The device for measuring the minimum dynamic clearance between a piston and a valve according to claim 3, characterized in that: The upper end of the piston (1) is provided with a groove (12), the groove (12) is located directly below the valve, and the first threaded hole (4) is provided on the groove (12).

5. The device for measuring the minimum dynamic clearance between a piston and a valve according to claim 4, characterized in that: The upper end of the first bolt (6) is provided with a slot (9), and the bottom end of the first bolt (6) is provided with a chamfer (10).

6. The device for measuring the minimum dynamic clearance between a piston and a valve according to claim 5, characterized in that: The first bolt (6) and the second bolt (7) are made of copper.

7. The device for measuring the minimum dynamic clearance between a piston and a valve according to claim 2, characterized in that: The first bolt (6) and the second bolt (7) are located on the same circumference.

8. The device for measuring the minimum dynamic clearance between a piston and a valve according to claim 1, characterized in that: A cavity (11) is provided in the middle of the piston (1).

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