Apparatus and method for simulating the behavior of a tire in a plunger test

Abstract

Provide an apparatus and method for simulating the behavior of a tire in a plunger test. **Solution**: An apparatus for simulating the behavior of a tire in a plunger test, comprising a grounding plate suitable for being firmly fixed to a tire support hub of a plunger testing machine, a support plate movably connected to the grounding plate by damping means, and only displacement along a preferred movement axis being permitted by the damping means, a pneumatic or hydraulic actuator connected to the support plate and suitable for being filled with a compressed fluid during operation and comprising an actuator piston, an actuating means connected to the grounding plate and suitable for causing the discharge of the compressed fluid in a pneumatic or hydraulic cylinder during operation, and a switching means connected to the support plate and suitable for engaging with the actuating means when the support plate is displaced, wherein the support plate is suitable for moving along the preferred movement axis when displacement is applied to the actuator rod.

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for simulating the physical behavior during a test, as a substitute for a tire in a tire strength test.

Background Art

[0002] A tire strength test or "plunger test" is one of several mandatory test requirements that a tire must meet according to the regulations of a particular country in order to receive the necessary government certification to release the tire to the market.

[0003] The Federal Motor Vehicle Safety Standard (FMVSS) 139 in the United States is an example of such a regulation.

[0004] In a tire strength test or "plunger test", the force applied through a plunger rod at the center of the tread width of the tire and the amount of displacement due to the deformation of the tire are measured by a tire strength tester or a plunger tester until the tire bursts and breaks by the plunger rod.

[0005] The energy at the breaking point required to break the tire is calculated by the formula "Energy = Force × Displacement ÷ 2" defined by the regulations.

[0006] The tire passes or fails the tire strength test or "plunger test" according to the energy required to break the tire.

[0007] As is immediately apparent, the tire strength test or "plunger test" is a destructive test, and at the end of the test, the tire must be destroyed by bursting and discarded, so it cannot be used anymore or used a second time.

[0008] This is a drawback when it is necessary to correlate different test apparatuses (and their test results) with each other, or when it is necessary to monitor the stability of the performance of the same apparatus.

[0009] Therefore, in this type of test, rather than using an actual tire, there is an increasing need to find an alternative means that can repeatedly and comparably reproduce the same tire operation over time with different devices.

[0010] Patent Document 1 discloses a test apparatus for tire tread strength and bead deviation. More specifically, it discloses a technique that can simultaneously perform a tire tread strength test and a bead tread test on a single testing machine while automatically measuring the load and displacement of the test object.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention has no above-mentioned drawbacks in the prior art. In particular, it provides an apparatus for simulating the behavior of a tire in a plunger test that can be easily and inexpensively implemented.

[0013] The present invention further has no above-mentioned drawbacks in the prior art. In particular, it provides a method for simulating the behavior of a tire in a plunger test that can be easily and inexpensively implemented.

Means for Solving the Problems

[0014] According to the present invention, as described in the appended claims, an apparatus for simulating the behavior of a tire in a plunger test and a method for simulating the behavior of a tire in a plunger test are provided.

[0015] This device comprises a grounding plate suitable for being firmly fixed to a plunger testing machine, a support plate movably connected to the grounding plate by damping means, a pneumatic or hydraulic actuator connected to the support plate and provided with an actuator piston, actuating means suitable for causing the discharge of the pneumatic or hydraulic cylinder, and switching means suitable for engaging with the actuating means when the support plate is displaced.

[0016] This device may further comprise guide means connected to the grounding plate for guiding the support plate when the support plate is displaced.

[0017] This device may further comprise a displacement meter suitable for measuring the relative displacement between the grounding plate and the support plate.

[0018] The grounding plate is suitable for being firmly fixed to the tire support hub of the plunger testing machine.

[0019] The grounding plate is preferably fixed to the tire support hub of the plunger testing machine via fixing means.

[0020] The damping means for connecting the support plate to the grounding plate allows only displacement along the preferred movement axis.

[0021] The support plate is suitable for moving along the preferred movement axis when displacement is applied to the actuator piston.

[0022] The grounding plate and the support plate preferably have the same shape, dimensions, and surface area.

[0023] The pneumatic or hydraulic actuator connected to the support plate is suitable for being filled with a compressed fluid during operation.

[0024] The pneumatic or hydraulic actuator is a pneumatic cylinder.

[0025] The actuating means may be connected to the grounding plate. The actuating means may be firmly connected to the grounding plate.

[0026] The actuating means is suitable for causing the discharge of the compressed fluid in the pneumatic or hydraulic cylinder when actuated.

[0027] The actuating means may be a mechanical actuating means (e.g., a lever) or an optical actuating means (e.g., a photovoltaic cell).

[0028] The switching means may be connected to the support plate.

[0029] This device may further include a positioning rod. The positioning rod can be connected to the grounding plate. The actuating means can be connected to the grounding plate via the positioning rod. The positioning rod is suitable for positioning the actuating means at different positions along the preferred movement axis.

[0030] The damping means includes at least a spring.

[0031] The damping means is preferably symmetrically arranged on the surfaces of the grounding plate and the support plate.

[0032] The grounding plate and the support plate are preferably rectangular.

[0033] The damping means is preferably dispersedly arranged at two locations on the distal side of the surfaces of the grounding plate and the support plate.

[0034] The present invention will be described with reference to the accompanying drawings showing some non-limiting exemplary embodiments.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0036] In FIG. 1, reference numeral 1 denotes an apparatus (also referred to as a plunger test simulator tool) for simulating the behavior of a tire in a plunger test as a whole.

[0037] The apparatus 1 includes a grounding plate 2 that is firmly fixed to the tire support hub 50 of a plunger testing machine 100 (only a schematic view) via fixing means 13. The fixing means 13 is preferably an elongated rod that passes under the tire support hub 50 and is preferably fixed to the grounding plate 2 via screws, thereby fixing the tire support hub 50 between the grounding plate 2 and the elongated rod.

[0038] To ensure measurement accuracy, it is important to firmly fix the grounding plate 2 of the apparatus 1 to the tire support hub 50 of the plunger testing machine 100 and suppress any movement of the grounding plate 2.

[0039] This apparatus 1 further includes a support plate 3 that is movably connected to the grounding plate 2 by damping means 4.

[0040] The damping means 4 extends from the upper surface of the grounding plate 2 to the lower surface of the support plate 3.

[0041] The upper surface of the grounding plate 2 and the lower surface of the support plate 3 are parallel to each other.

[0042] The support plate 3 is supported by the damping means 4.

[0043] The damping means 4 preferably includes at least a spring.

[0044] The damping means 4 preferably includes a plurality of springs.

[0045] In addition to the function of supporting the support plate 3, the damping means 4 has a function of reproducing the vertical rigidity of the actual tire.

[0046] To reproduce different sizes of actual tires, or more generally, different categories of tires (passenger car tires, commercial van tires, truck tires, etc.), and different air pressure conditions, specific calibration of the damping means 4 is required.

[0047] As shown in FIG. 7, the displacement amount of the plunger 10 due to the force applied to the tire is plotted during the plunger test. The average slope of the obtained graph is the vertical rigidity of the tire and represents its spring constant k.

[0048] In FIG. 7, the solid line represents the result of the plunger test using a device for simulating the behavior of the tire in the plunger test, the dashed line represents the result of an actual tire of size 265 / 30R21 with a spring constant of about 10.5 kg / mm, and the dotted line represents the result of an actual tire of size 265 / 30R21 with a spring constant of about 7.5 kg / mm. The air pressure of both tires was set to 2.0 bar. The spring constant of the damping means 4 is about 8.9 kg / mm.

[0049] Calibration of the damping means 4 means that the sum of the spring constants of the damping means 4 represents the range of the spring constants of a specific tire type.

[0050] The following table shows the assumed ranges of the spring constants of different categories of tires.

[0051]

Table 1

[0052] The damping means 4 should be calibrated and selected so that it can represent the vertical rigidity of the tire category, i.e., the spring constant.

[0053] If a specific tire size and specification are known, it is also possible to reproduce the exact spring constant of that tire.

[0054] In a preferred embodiment, the damping means 4 is composed of 12 single springs. If the total spring constant k T of the damping means 4 is 8.9 kg / mm, in the embodiments shown in FIGS. 1 to 5, since the springs of the damping means 4 are in a parallel configuration, the spring constant k S of each spring is 0.74 kg / mm.

[0055] The damping means 4 is symmetrically arranged on the upper surface of the grounding plate 2 and the lower surface of the support plate 3 in order to uniformly disperse the load on the support plate and the load applied during the plunger test.

[0056] By arranging the damping means 4 symmetrically, it is also possible to keep the upper surface of the grounding plate 2 and the lower surface of the support plate 3 parallel while the support plate 2 is displaced.

[0057] Preferably, the grounding plate 2 and the support plate 3 are rectangular and have the same dimensions. That is, the upper surface of the grounding plate 2 and the lower surface of the support plate 3 have the same surface area.

[0058] Preferably, the damping means 4 are respectively dispersedly arranged at two distal positions on the upper surface of the grounding plate and the lower surface of the support plate.

[0059] The damping means 4 that connects the support plate 3 to the grounding plate 2 preferably allows only displacement along the preferred movement axis. The preferred movement axis is perpendicular to both the upper surface of the grounding plate 2 and the lower surface of the support plate 3.

[0060] To ensure that the displacement of the support plate 3 occurs only along the preferred movement axis, the device 1 preferably includes guide means 9.

[0061] The guide means 9 extends in the preferred movement axis direction and is fixedly connected to the grounding plate 2.

[0062] The guide means 9 is preferably a rod or shaft with a circular cross-section.

[0063] Preferably, the device 1 comprises the same number of guide means 9 as the damping means 4.

[0064] Preferably, the guide means 9 and the damping means 4 are coaxial with each other, that is, each element of the guide means 9 is coaxial with a single element of the damping means 4.

[0065] Preferably, the guide means 9 are respectively arranged axially inside the damping means 4, in other words, each element of the damping means 4 surrounds the element of the guide means 9.

[0066] The support plate 3 has at least one through hole, and its dimension is such that the guide means 9 can pass through it, but the damping means 4 cannot pass through it.

[0067] The guide means 9 comprises a limiting element 14 located at the distal end from the grounding plate 2. The limiting element 14 is located at the end of the guide means 9 passing through the through hole of the support plate 3. The limiting element 14 is arranged on the side of the support plate 3 opposite to the damping means 4.

[0068] The limiting element 14 has, firstly, the function of fixing the support plate 3 to the guide means 9, more precisely, the function of fixing the support plate 3 so that it does not move beyond the guide means 9, and secondly, the function of adjusting the initial compression of the damping means 4.

[0069] The initial compression of the damping means 4 means the compression of the spring when no force is applied to the device 1 through the plunger 10.

[0070] The limiting element 14 preferably comprises a ring and a bolt.

[0071] The limiting element 14 is preferably connected to the guide means 9 via a screw.

[0072] The apparatus 1 further comprises a pneumatic or hydraulic actuator 5 firmly connected to the support plate 3.

[0073] The pneumatic or hydraulic actuator 5 comprises an actuator piston 6.

[0074] The pneumatic or hydraulic actuator 5 is preferably a pneumatic or hydraulic cylinder.

[0075] The pneumatic or hydraulic actuator 5 is suitable for being filled with a compressed fluid during operation. When the pneumatic or hydraulic actuator 5 is filled with the compressed fluid, it moves the actuator piston 6 to the extended position as shown in FIG. 3.

[0076] Conversely, when the compressed fluid is discharged from the pneumatic or hydraulic actuator 5, the actuator piston 6 retracts to the retracted position as shown in FIG. 1 or 2.

[0077] The movement axis T of the actuator piston 6 is parallel to the preferred movement axis.

[0078] The apparatus 1 further comprises actuating means 7 suitable for causing the discharge of the pneumatic or hydraulic cylinder 5.

[0079] When the actuating means 7 engages or operates, it prompts the pneumatic or hydraulic actuator 5 to discharge the compressed fluid, thereby simulating the damage of the tire.

[0080] The actuating means 7 is preferably mechanical actuating means 7 (e.g., a lever) or optical actuating means 7 (e.g., a photocell).

[0081] The actuating means 7 is preferably connected to the grounding plate 2.

[0082] The device 1 may further include a positioning rod 11. The positioning rod is preferably connected to the grounding plate 2.

[0083] The actuating means 7 is preferably connected to the grounding plate via the positioning rod 11.

[0084] The positioning rod 11 is suitable for positioning the actuating means 7 at different positions or heights along the preferred movement axis T.

[0085] The device 1 further includes switching means 8 suitable for engaging with the actuating means 7.

[0086] The switching means 8 is preferably connected to the support plate 3.

[0087] The switching means 8 is suitable for engaging with the actuating means 7 upon a predetermined displacement of the support plate 3.

[0088] The switching means 8 is configured to engage with the actuating means 7 to simulate tire damage.

[0089] The switching means 8 is configured to engage with the actuating means 7 when the support plate 3 is displaced by a predetermined displacement amount along its displacement 3.

[0090] The predetermined displacement amount of the support plate 3 corresponds to the displacement required for the switching means 8 to be able to engage with the actuating means 7.

[0091] By arranging the actuating means 7 at different positions or heights, it is possible to select a predetermined displacement amount of the support plate 3 such that the switching means 8 engages with the actuating means 7, and as a result, the device 1 simulates tire damage.

[0092] The device 1 may further include a displacement gauge 16 for measuring the displacement amount between the grounding plate 2 and the support plate 3 during the plunger test.

[0093] The device 1 may further include a load cell 17 (not shown) located between the actuator piston 6 and the plunger 10 at the outer end of the actuator piston 6.

[0094] The load cell 17 is suitable for measuring the force applied to the device 1 that simulates the behavior of the tire during the plunger test.

[0095] A method for calculating the energy required to break the tire during the plunger test can be obtained from the measurement of the applied force by the load cell 17 and the displacement amount between the ground plate 2 and the support plate 3.

[0096] The measurement of the force and displacement amount by the load cell 17 and the displacement meter 16 provides comparative data in addition to or instead of the measurement data by the plunger tester itself. The additional comparative data set can also be used to confirm the proper functioning of the plunger tester.

[0097] During operation, the device 1 is mounted on the tire support hub 50 of the plunger tester 100, and the pneumatic or hydraulic actuator 5 is filled with a compressed fluid, causing the actuator piston 6 to move to the extended position. Before starting the plunger test, as shown in FIG. 3, the plunger 10 of the plunger tester 100 is pressed against the actuator piston 6.

[0098] During the procedure of the plunger test, a force is applied to the plunger 10 of the tester, as a result of which, as shown in FIGS. 4 and 5, the actuator piston 6 and the pneumatic or hydraulic actuator 5 are displaced.

[0099] Since the pneumatic or hydraulic actuator 5 is firmly connected to the support plate 3, the support plate 3 is pushed downward, that is, toward the ground plate 2 along the preferred movement axis.

[0100] Thereby, the damping means 4 is compressed.

[0101] The switching means 8 arranged on the support plate 3 engages with the actuating means 7 at a predetermined height (see FIGS. 5 and 6), thereby causing the discharge of the compressed fluid from the pneumatic or hydraulic actuator 5 and simulating the damage of the tire.

[0102] The present invention also provides a method for simulating the behavior of a tire during a plunger test.

[0103] This method includes using the device 1 instead of an actual tire during the plunger test.

[0104] This method includes the steps of attaching the device 1 to the tire support hub 50 of the plunger testing machine 100, filling the pneumatic or hydraulic actuator 5 with compressed fluid to move the actuator piston 6 to the extended position, pushing the plunger 10 of the plunger testing machine 10 against the actuator piston 6, applying a force to the plunger 10 to start the plunger test, and displacing the support plate 3 by the force applied to the actuator piston 6 until the switching means 8 engages with the actuating means 7, thereby causing the discharge of the compressed fluid from the pneumatic or hydraulic actuator 5 and simulating the damage of the tire.

[0105] This method can further include the steps of providing a load cell 17 between the actuator piston 6 and the plunger 10, measuring the applied force and the displacement amount between the grounding plate 2 and the support plate 3 during the test, and calculating the energy at the time when a simulation of tire damage occurs.

Explanation of Reference Numerals

[0106] 1 Device 2 Grounding plate 3 Support plate 4 Damping means 5 Pneumatic or hydraulic actuator 6 Actuator piston 7 Actuating means 8 Switching means 9 Guide means 10 Plunger 11 Positioning rod 13 Fixing means 14 Limiting element 15 Tire support hub 16 Displacement meter 17 Load cell 100 Plunger tester T Preferred movement axis

Claims

1. An apparatus for simulating the behavior of a tire in a plunger test, comprising: A grounding plate suitable for being firmly fixed to a tire support hub of a plunger testing machine; A support plate movably connected to the grounding plate by damping means, and only displacement along a preferred movement axis is allowed by the damping means; A pneumatic or hydraulic actuator connected to the support plate, suitable for being filled with compressed fluid during operation, and comprising an actuator piston; Actuating means connected to the grounding plate, suitable for causing the discharge of the compressed fluid in the pneumatic or hydraulic actuator during operation; Switching means connected to the support plate, suitable for engaging with the actuating means at a predetermined displacement of the support plate; The support plate is suitable for moving along the preferred movement axis when a force is applied to the actuator piston.

2. The apparatus according to claim 1, further comprising a positioning rod connected to the grounding plate, wherein the actuating means is connected to the grounding plate via the positioning rod, and the positioning rod is suitable for positioning the actuating means at different positions along the preferred movement axis.

3. The apparatus according to claim 1 or 2, wherein the damping means comprises at least a spring.

4. The apparatus according to any one of claims 1 to 3, wherein the damping means is symmetrically arranged on the surfaces of the grounding plate and the support plate.

5. The apparatus according to claim 4, wherein the damping means is dispersedly arranged at two distal positions on the surfaces of the grounding plate and the support plate.

6. The apparatus according to any one of claims 1 to 5, wherein the pneumatic or hydraulic actuator is a pneumatic cylinder.

7. The apparatus according to any one of claims 1 to 6, further comprising a displacement meter for measuring the displacement amount of the support plate relative to the grounding plate.

8. The apparatus according to any one of claims 1 to 7, further comprising a load cell connected to the actuator piston for measuring the force applied to the actuator piston.

9. The apparatus according to any one of claims 1 to 8, wherein the damping means has a spring constant in any one of the ranges of 5 - 12 kg / mm, 13 - 22 kg / mm, or 30 - 50 kg / mm.

10. A method for performing a plunger test with a plunger testing machine using the apparatus according to any one of claims 1 to 9, comprising: fixing the apparatus to a support hub of the plunger testing machine; filling the pneumatic or hydraulic actuator with fluid to thereby lift the actuator rod toward the plunger of the plunger testing machine; applying a force to the actuator piston via the plunger and displacing the support plate along a suitable movement axis to start the plunger test; ending the test when the switching means engages with the operating means due to the displacement of the support plate.

11. measuring the displacement amount of the support plate via a displacement meter; measuring the force applied to the plunger via a load cell; further comprising calculating the energy at the time when a simulation of tire breakage occurs, the method according to claim 10.

12. The method according to claim 11, further comprising selecting the damping means from one of the groups of the damping means having a spring constant in the range of 5 to 12 kg / mm, 13 to 22 kg / mm, or 30 to 50 kg / mm.

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