A device and method for measuring collision impact force and action time

Abstract

The present invention discloses a device and method for measuring the impact force and action time of a collision, a balancing platform, a balancing platform bracket, a hanging weight, a vertical line and a collision block; a vertical through hole is provided on the right side of the balancing platform, and a hanging screw hole is provided on the left side; a hanging screw is distributed in the hanging screw hole; a supporting shaft is provided on the upper part of the balancing platform bracket; a wire switch device and an oscilloscope are also included, and two exposed wire ends are provided on the top of the wire switch device; the hanging weight is made of conductive material and can be movably distributed on the exposed wire ends; the two exposed wire ends are connected to a power supply resistance module and the oscilloscope, and the hanging weight is connected to the two exposed wire ends to form a loop. The present invention has the advantages of accurate and convenient detection and good use effect.

Description

Technical Field

[0001] The invention relates to the technical field of automobile testing, and in particular to a device and method for measuring collision impact force and action time. Background Art

[0002] When a car is driving at high speed on the road and its tire collides with pits, bosses, stones, steps, etc. on the road, it will generate an instant impact force on the relevant parts of the engine, such as the engine body, cylinder head, piston, etc. The parts in the engine that move at high speed, such as the valve chain mechanism, camshaft, crankshaft, etc., will also generate an instant impact force during the movement. The instant impact force and its duration of action on the parts of the car and the engine are difficult to measure and study because the action time is very short (the measured rigid collision action time is about a few milliseconds). In actual engineering applications, the rocker shaft bolts of a four-valve engine often break. Analysis shows that excessive impact force is one of the main reasons. The rocker shaft bolt is used to fix the rocker shaft. The rocker shaft is a cylindrical shaft with rockers on both sides. The middle is fastened with rocker shaft bolts. The rocker can swing around the axis of the rocker shaft. The front end of the rocker arm contacts the valve bridge, and the valve bridge contacts the valve; the rear end of the rocker arm contacts the push rod, and the push rod contacts the tappet, and the tappet contacts the camshaft bump and is driven by the camshaft bump. When the engine is working, especially at high speed, driven by the camshaft bump, the front end of the rocker arm and the valve bridge, and the rear end and the push rod will collide at high speed, generating a collision impact force.

[0003] Research has found that the stress of combustion impact will be amplified and propagated along the valve in the form of stress waves, and will be emitted after reaching the valve bridge. Under certain conditions, the valve bridge can bounce with a certain momentum and collide with the rocker arm and generate a force. When a car passes through an uneven road at high speed (a road with pits, bosses, large stones, etc.), the collision impact generated will also be transmitted to the engine valve chain, causing the front end of the rocker arm to collide violently with the valve bridge and valve or the rear end of the rocker arm to collide violently with the push rod and tappet, thereby generating a large impact force. The impact force generated by the above situation may also be superimposed under certain conditions, so that the rocker shaft supporting the rocker arm is subjected to excessive force, and finally the rocker shaft bolt breaks. The existing technology can use a special mechanical vibration test bench to test the size and action time of the collision impact force, but it requires a variety of high-precision equipment, such as impact loading equipment, high strain rate dynamic strain measurement equipment, displacement measurement equipment, photoelectric speed measurement equipment and supporting data acquisition and analysis equipment, etc. At the same time, it is not only complicated to operate but also has high testing costs. Most of them can only be used in laboratories and are difficult to be used in enterprise production.

[0004] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0005] In view of the above technical problems, the present invention provides a device and method for measuring the collision impact force and action time of an engine rocker arm after being impacted.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] A device for measuring the force and time of a collision impact, comprising a balancing platform, a balancing platform bracket, a hanging weight, a vertical line and a collision block; a vertical through hole is provided on the right side of the balancing platform, and a hanging screw hole is provided on the left side thereof; a hanging screw is distributed in the hanging screw hole; a supporting shaft is provided on the upper part of the balancing platform bracket; a plurality of strip grooves are provided on the lower plate surface of the balancing platform corresponding to the supporting shaft; the balancing platform is movably distributed on the supporting shaft through the strip grooves; the hanging weight is detachably connected to the lower end of the hanging screw by providing a screw groove; the upper end of the vertical line is fixed to a building and is distributed through the vertical through hole; the lower end of the vertical line is in a straightened state by hanging a heavy object or connecting to a floor; a vertical through hole is provided in the middle of the collision block and is distributed above the balancing platform through the vertical line;

[0008] It also includes a wire switch device and an oscilloscope, wherein the top of the wire switch device is provided with two exposed wire ends; the hanging weights are made of conductive material and are movably distributed on the exposed wire ends; the two exposed wire ends are connected to a power supply-resistance module and the oscilloscope, and the hanging weights are connected to the two exposed wire ends to form a loop.

[0009] Furthermore, it also includes a vertical scale, which is distributed on one side of the collision block, and an alignment mark is provided on the collision block.

[0010] Furthermore, it also includes a plumb bob, which is hung at the lower end of the vertical line.

[0011] Furthermore, a collision platform is further provided on the right side of the balancing platform, a through hole is opened in the middle of the collision platform corresponding to the vertical through hole, and is correspondingly combined above the vertical through hole.

[0012] Furthermore, the material used for the balancing platform is the same as the material of the engine rocker arm to be studied.

[0013] Furthermore, the structure of the collision platform is the same as the shape of the collision part of the engine rocker arm to be studied, that is, the front end or the rear end thereof.

[0014] The method for testing using the collision impact force and action time measuring device as described above comprises the following steps:

[0015] (1) Selecting a balancing platform of a corresponding model according to the model of the research object, i.e., the engine rocker arm, so that the center distance between the vertical through hole and the suspension screw hole is the same as the distance between the collision center of the front end of the engine rocker arm to be studied and the collision center of the rear end;

[0016] (2) selecting the collision block made of the same mass and the same material according to the research object, i.e., the engine valve bridge and valve or the push rod and tappet;

[0017] (3) According to the left-right ratio of the rocker arm shaft supporting the engine rocker arm of the research object, the support shaft is distributed on the corresponding strip groove, so that the left-right ratio of the balance platform corresponds to the above ratio;

[0018] (4) After the measuring device is installed as required, when the collision block does not act on the balancing platform, the balancing platform is in a horizontal state, and the bottom of the hanging weight is in contact with the two exposed wire ends, ensuring that the oscilloscope displays normally;

[0019] (5) Assume that the front end of the object to be studied is hit by a part with a mass of m and a speed of v. Then a collision block with a mass of m is selected and placed at a height of H = v from the collision table. 2 / 2g falls vertically along the vertical line. According to the free fall formula, when the collision block collides with the collision platform, the speed is exactly v;

[0020] (6) Observe the circuit waveform of the oscilloscope. If the oscilloscope shows that the current waveform is not disconnected, the weight is too heavy. It is necessary to use the same height and lighter hanging weight and re-measure until a hanging weight is found that just disconnects the current after the collision. This is recorded as the standard hanging weight.

[0021] If the oscilloscope shows that the current waveform is disconnected, it means that the selected hanging weight may be too light, and it is necessary to use a slightly heavier hanging weight of the same height and re-measure until a hanging weight is found that does not disconnect the current after the collision, and record it as the pending hanging weight. Then, use a hanging weight slightly heavier than the pending hanging weight and measure again until a hanging weight is found that just disconnects the current after the collision, and record it as the standard hanging weight.

[0022] (7) The mass of the standard hanging weight that can just disconnect the current after the collision is recorded as M. Then it can be considered that after one end of the object to be studied is hit, the equivalent force generated at the other end is F1 = Mg;

[0023] (8) Let the distance from the center of the hanging weight to the fulcrum of the balance platform be L1, and the distance from the center of the collision platform to the fulcrum of the balance platform be L2; let the equivalent force on the collision platform after the collision impact be F2, then according to the principle of lever, F1L1=F2L2, that is, F2=F1L1 / L2=MgL1 / L2; the resultant force on the fulcrum is F=F1+F2=Mg+MgL1 / L2, which is the equivalent force on the fastening bolt of the object to be studied after the collision impact of the part with mass m and velocity v;

[0024] (9) Rigid collision can be considered as momentum conservation. The collision block falls freely from a height H and rebounds to a height h after colliding with the collision table. The height h is observed and recorded by the vertical scale or recorded by a high-speed camera and compared with the vertical scale. The velocity v of the rebound is 反 =(2gh) 1 / 2 , assuming that the collision time between the collision block and the collision platform is t, then according to the law of conservation of momentum: mv-mv 反 =F2t, the collision time t = m(vv 反 ) / F2=m((2gH) 1 / 2 -(2gh) 1 / 2 ) / (MgL1 / L2).

[0025] The beneficial effects of the present invention compared with the prior art are as follows: the device of the present invention has a simple structure and ingenious design, adopts a plumb bob and a vertical line for guiding and realizing elastic limiting, and is combined with a balance platform bracket, an oscilloscope and an adjustable weight switch assembly to achieve the beneficial effects of accurate, fast and low-cost detection. At the same time, the method is used to measure the collision impact force and action time of the engine rocker arm after the impact, which has the effects of convenient operation, strong reliability, good repeatability and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0027] like Figure 1As shown, a device for measuring the impact force and time of a collision, comprises a balancing platform 4, a balancing platform bracket 1, a hanging weight 18, a vertical line 9 and a collision block 12; a vertical through hole 7 is provided on the right side of the balancing platform 4, and a hanging screw hole 4-1 is provided on the left side thereof; hanging screws 14 are distributed in the hanging screw holes; of course, the vertical through hole 7 is a small hole, mainly to prevent the balancing platform 4 from tilting too much after being hit, and the aperture thereof is matched with the diameter of the vertical line 9, as long as it does not interfere with the hanging weight 18 just bouncing off the two exposed wire ends 17, that is, it cannot be opened too small, so as not to hinder the hanging weight 18 from just bouncing off the two exposed wire ends 17, and ensure that the oscilloscope 19 can accurately receive the disconnected current signal without interference. The upper part of the balance platform bracket 1 is provided with a support shaft 3. In this embodiment, two vertical support arms 2 are provided in front and back, and then the support shaft 3 is combined between the two support arms 2. A plurality of strip grooves 5 are provided on the lower plate surface of the balance platform 4 corresponding to the support shaft 3, which are used to select different support points when testing to obtain the required left-right ratio. The balance platform 4 is movably distributed on the support shaft 3 through the strip grooves 5. The hanging weight 18 is detachably combined with the lower end of the hanging screw 14 by providing a screw groove 15. The hanging weight 18 is made of conductive material, and the heights of the hanging weights 18 of different masses in the same series are generally consistent. The upper end of the vertical line 9 is fixed to the building and distributed through the vertical through hole. The lower end of the vertical line 9 is in a straightened state by hanging a heavy object or connecting the floor. In this embodiment, a plumb bob 8 is provided, and the plumb bob 8 is suspended at the lower end of the vertical line. The use of the hanging plumb bob 8 can effectively improve safety and prevent excessive contact and wear between the vertical line 9 and the inner cavity of the vertical through hole 7 that may occur during a collision. The collision block is provided with a vertical line through hole 13 in the middle, and the vertical line is passed through the vertical line and distributed above the balance platform; it also includes a wire switch device 16 and an oscilloscope 19, and the top of the wire switch device is provided with two exposed wire ends 17; and they are movably distributed on the exposed wire ends; the two exposed wire ends are connected to the power supply-resistance module and the oscilloscope, and the hanging weight is connected to the two exposed wire ends to form a loop. It also includes a vertical scale 11, which is distributed on one side of the collision block, and an alignment mark 10 is provided on the collision block 12.

[0028] A collision platform 6 is also provided on the right side of the balancing platform. A through hole is opened in the middle of the collision platform 6 corresponding to the vertical through hole, and is correspondingly combined above the vertical through hole. The collision platform 6 of this embodiment can be integrally formed with the balancing platform 4 or detachably assembled.

[0029] Furthermore, the material used for the balancing platform is the same as the material of the engine rocker arm to be studied.

[0030] Furthermore, the structure of the collision platform is the same as the shape of the collision part of the engine rocker arm to be studied, that is, the front end or the rear end thereof.

[0031] The method for testing using the collision impact force and action time measuring device as described above comprises the following steps:

[0032] (1) Selecting a balancing platform of a corresponding model according to the model of the research object, i.e., the engine rocker arm, so that the center distance between the vertical through hole and the suspension screw hole is the same as the distance between the collision center of the front end of the engine rocker arm to be studied and the collision center of the rear end;

[0033] (2) selecting the collision block made of the same mass and the same material according to the research object, i.e., the engine valve bridge and valve or the push rod and tappet;

[0034] (3) According to the left-right ratio of the rocker arm shaft supporting the engine rocker arm of the research object, the support shaft is distributed on the corresponding strip groove, so that the left-right ratio of the balance platform corresponds to the above ratio;

[0035] (4) After the measuring device is installed as required, when the collision block does not act on the balancing platform, the balancing platform is in a horizontal state, and the bottom of the hanging weight is in contact with the two exposed wire ends, ensuring that the oscilloscope displays normally;

[0036] (5) Assume that the front end of the object to be studied is hit by a part with a mass of m and a speed of v. Then a collision block with a mass of m is selected and placed at a height of H = v from the collision table. 2 / 2g falls vertically along the vertical line. According to the free fall formula, when the collision block collides with the collision platform, the speed is exactly v;

[0037] (6) Observe the circuit waveform of the oscilloscope. If the oscilloscope shows that the current waveform is not disconnected, the weight is too heavy. It is necessary to use the same height and lighter hanging weight and re-measure until a hanging weight is found that just disconnects the current after the collision. This is recorded as the standard hanging weight.

[0038] If the oscilloscope shows that the current waveform is disconnected, it means that the selected hanging weight may be too light, and it is necessary to use a slightly heavier hanging weight of the same height and re-measure until a hanging weight is found that does not disconnect the current after the collision, and record it as the pending hanging weight. Then, use a hanging weight slightly heavier than the pending hanging weight and measure again until a hanging weight is found that just disconnects the current after the collision, and record it as the standard hanging weight.

[0039] (7) The mass of the standard hanging weight that can just disconnect the current after the collision is recorded as M. Then it can be considered that after one end of the object to be studied is hit, the equivalent force generated at the other end is F1 = Mg;

[0040] (8) Let the distance from the center of the hanging weight to the fulcrum of the balance platform be L1, and the distance from the center of the collision platform to the fulcrum of the balance platform be L2; let the equivalent force on the collision platform after the collision impact be F2, then according to the principle of lever, F1L1=F2L2, that is, F2=F1L1 / L2=MgL1 / L2; the resultant force on the fulcrum is F=F1+F2=Mg+MgL1 / L2, which is the equivalent force on the fastening bolt of the object to be studied after the collision impact of the part with mass m and velocity v;

[0041] (9) Rigid collision can be considered as momentum conservation. The collision block falls freely from a height H and rebounds to a height h after colliding with the collision table. The height h is observed and recorded by the vertical scale or recorded by a high-speed camera and compared with the vertical scale. The velocity v of the rebound is 反 =(2gh) 1 / 2 , assuming that the collision time between the collision block and the collision platform is t, then according to the law of conservation of momentum: mv-mv 反 =F2t, the collision time t = m(vv 反 ) / F2=m((2gH) 1 / 2 -(2gh) 1 / 2 ) / (MgL1 / L2).

Claims

1. A device for measuring collision impact force and action time, characterized in that: A balancing platform, a balancing platform bracket, a hanging weight, a vertical line and a collision block; a vertical through hole is provided on the right side of the balancing platform, and a hanging screw hole is provided on the left side thereof; a hanging screw is distributed in the hanging screw hole; a supporting shaft is provided on the upper part of the balancing platform bracket; a plurality of strip grooves are provided on the lower plate surface of the balancing platform corresponding to the supporting shaft; the balancing platform is movably distributed on the supporting shaft through the strip grooves; the hanging weight is detachably connected to the lower end of the hanging screw by providing a screw groove; the upper end of the vertical line is fixed to the building and passes through the vertical The vertical line is arranged in a straight-through hole distribution; the lower end of the vertical line is in a straightened state by hanging a weight or connecting to the floor; a vertical line through-hole is opened in the middle of the collision block, and passes through the vertical line and is distributed above the balance platform; it also includes a wire switch device and an oscilloscope, and the top of the wire switch device is provided with two exposed wire ends; the hanging weight is made of conductive material, and it is movably distributed on the exposed wire ends; the two exposed wire ends are connected to the power supply-resistance module and the oscilloscope, and the hanging weight is connected to the two exposed wire ends to form a loop; It also includes a vertical scale, which is correspondingly distributed on one side of the collision block, and an alignment mark is provided on the collision block; A collision platform is also provided on the right side of the balancing platform, a through hole is opened in the middle of the collision platform corresponding to the vertical through hole, and is correspondingly combined above the vertical through hole; The structure of the collision platform is the same as the shape of the front end or rear end of the collision part of the engine rocker arm to be studied; The material used for the balancing platform is the same as that of the rocker arm of the engine to be studied.

2. A device for measuring collision impact force and action time according to claim 1, characterized in that: Also included is a plumb bob suspended at the lower end of the vertical line.

3. A method for testing using a device for measuring collision impact force and action time as claimed in any one of claims 1 to 2, characterized in that: The method comprises the following steps: (1) selecting a balancing platform of a corresponding model according to the model of the engine rocker arm, so that the center distance between the vertical through hole and the suspension screw hole is the same as the distance between the collision center of the front end and the collision center of the rear end of the engine rocker arm to be studied; (2) selecting the collision block made of the same mass and material according to the engine valve bridge and valve or push rod and tappet; (3) adjusting the distribution of the support shaft on the corresponding strip groove according to the left-right ratio of the rocker shaft supporting the engine rocker arm of the research object, so that the left-right ratio of the balancing platform corresponds to the above ratio; (4) after the measuring device is installed as required, when the collision block is not acting on the balancing platform, the balancing platform is in a horizontal state, and the bottom of the suspension weight contacts the two exposed wire ends, so as to ensure that the oscilloscope displays normally; (5) assuming that the front end of the research object is collided by a part with a mass of m and a speed of v, a collision block with a mass of m is selected so that it is at a height H=v from the collision platform. 2 / 2g falls vertically along the vertical line. According to the free fall formula, when the collision block collides with the collision platform, the speed is exactly v; (6) observe the circuit waveform of the oscilloscope. If the oscilloscope shows that the current waveform is not disconnected, the weight is too heavy. It is necessary to use the hanging weight of the same height and lighter and re-measure until the hanging weight is found that the current is just disconnected after the collision. This is recorded as the standard hanging weight. If the oscilloscope shows that the current waveform is disconnected, it means that the selected hanging weight is too light. It is necessary to use a slightly heavier hanging weight of the same height and re-measure until the current is not disconnected after the collision. This is recorded as the pending hanging weight. Then Use a hanging weight slightly heavier than the pending hanging weight and measure again until a hanging weight is found that can just disconnect the current after the collision, and record it as the standard hanging weight; (7) Record the mass of the standard hanging weight that can just disconnect the current after the collision as M, then it is considered that the equivalent force generated at the other end of the object to be studied after the collision is F1 = Mg; (8) Let the distance from the center of the hanging weight to the fulcrum of the balance platform be L1, and the distance from the center of the collision platform to the fulcrum of the balance platform be L2; Let the equivalent force after the collision impact on the collision platform be F2, then according to the lever principle, F1L1 = F2L2, that is, F2 = F1L1 / L2 = Mg L1 / L2; the resultant force on the fulcrum is F = F1 + F2 = Mg + Mg L1 / L2. This resultant force is the equivalent force on the fastening bolt of the object to be studied after being impacted by a part with a mass of m and a speed of v. (9) Rigid collision is considered to be momentum conservation. The collision block falls freely from a height H and rebounds to a height h after colliding with the collision table. The height h is observed and recorded by the vertical scale or recorded by a high-speed camera and compared with the vertical scale. The speed v of the rebound is 反 =(2gh) 1 / 2 , assuming that the collision time between the collision block and the collision platform is t, then according to the law of conservation of momentum: mv-mv 反 =F2t, the collision time t = m(vv 反 ) / F2=m((2gH) 1 / 2 -(2gh) 1 / 2 ) / (Mg L1 / L2).

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