A floating model limit device for automobile wind tunnel force test

Abstract

The present invention relates to a floating model limiting device for automobile wind tunnel force test, comprising a clamping device provided with a rotating shaft, wherein the top of the clamping device is connected to the test vehicle, the bottom of the clamping device is connected to a floating support mechanism with variable height, the floating support mechanism is connected to a six-component force balance, the floating support mechanism is connected to a processor, the floating support mechanism outputs its own height floating distance data to the processor, and the processor converts the attitude change amount caused by the test vehicle under the influence of aerodynamic force according to the height floating distance data of the floating support mechanism. Compared with the prior art, the present invention can realize and measure the real attitude change of different automobile models under the action of aerodynamic force, and can improve the stability of the test model limit.

Description

Technical Field

[0001] The invention relates to the technical field of automobile wind tunnel testing, in particular to a floating model limiting device used for automobile wind tunnel force measurement test. Background Art

[0002] The automobile wind tunnel is an experimental facility used to study and measure various aerodynamic characteristics of automobiles by simulating the airflow and road conditions at an infinite distance ahead. Since the introduction of rolling road simulation technology in automobile wind tunnels in the 1990s, the wheels can rotate during force measurement in the wind tunnel. In order to ensure the fixed position of the model and the safety of the experiment, the model limiter is required to be fixed to the edge of the chassis longitudinal beam near the four wheels. The model limiter must be strong enough to resist the aerodynamic force and the reaction force of wheel rotation, but it cannot affect the actual flow field due to its large size.

[0003] The existing automobile wind tunnel model limit device is generally composed of a support rod and a chuck with a diameter of 16 to 20 mm made of high-strength steel. A rigid connection is generally adopted between the support rod and the chuck, that is, the model posture is completely locked, and the posture change function caused by the aerodynamic force of the real car body cannot be realized; at present, some automobile wind tunnels also use movable pin-type chucks, but due to the limitation of the chuck size, only a small range of floating is allowed, and the actual floating range of more than 10 mm or even 20 mm cannot be met. The safety performance of this method cannot be reliably guaranteed.

[0004] In addition, the automobile wind tunnel force measurement experiment must consider the installation and fixation of test vehicle models of different sizes and the need to adjust the front and rear body height during the test. When the adjustment is made through the vehicle fixing device and the front and rear height difference is large, it is very easy for the clamp to loosen, or the clamp is in a state of pulling the test vehicle, resulting in safety hazards such as vehicle escape during the test. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a floating model limit device for automobile wind tunnel force test, which can realize and measure the real posture changes of different automobile models under the action of aerodynamic force and improve the stability of the test model limit.

[0006] The objective of the present invention can be achieved through the following technical scheme: a floating model limiting device for automobile wind tunnel force test, comprising a clamping device provided with a rotating shaft, the top of the clamping device is connected to the test vehicle, the bottom of the clamping device is connected to a floating support mechanism with variable height, the floating support mechanism is connected to a six-component force balance, the floating support mechanism is connected to a processor, the floating support mechanism outputs its own height floating distance data to the processor, and the processor converts the attitude change amount caused by the test vehicle being affected by aerodynamic force according to the height floating distance data of the floating support mechanism.

[0007] Furthermore, the clamping device includes a movable chuck and a fixed chuck mounted on a rotating shaft, the movable chuck and the fixed chuck can rotate around a rotation, the rotating shaft is connected to a Y-shaped support, and the Y-shaped support is connected to a floating support mechanism through two symmetrically arranged locking blocks.

[0008] Furthermore, the movable clamp is provided with a threaded hole matching with the fixed clamp, and a bolt is installed in the threaded hole. By tightening the bolt, the movable clamp can be pulled to tighten and clamp the test vehicle, thereby ensuring a rigid connection between the clamping device and the test vehicle.

[0009] Furthermore, the floating support mechanism includes a fixed rod connected to the six-component force balance, and a floating rod that can slide up and down is installed in the fixed rod.

[0010] Furthermore, a limit pin for limiting the sliding displacement of the floating rod and a sliding potentiometer for detecting the up and down sliding distance of the floating rod are installed on the fixed rod.

[0011] Furthermore, a vertical guide groove cooperating with the limit pin is provided on the floating rod to ensure that the floating rod can slide up and down safely inside the fixed rod.

[0012] Furthermore, the sliding portion of the sliding potentiometer is connected to the fixing rod.

[0013] Furthermore, the upper end of the locking block is hung on the lower edge of the Y-shaped support, and the two locking blocks are connected by bolts, and are locked or opened by the bolts.

[0014] Furthermore, an upper conical surface and a lower conical surface are provided at the upper end of the floating rod, and the upper conical surface is matched and connected with a conical hole provided at the lower end of the Y-shaped support.

[0015] Furthermore, the inner wall of the locking block is cooperatively connected with the lower conical surface of the upper end of the floating rod, so as to maintain the rigid connection between the floating rod and the clamping device during locking.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. Improved adaptability and position limiting stability: The present invention increases the setting of a rotating shaft in the clamping device, so that the clamping device can rotate with the test vehicle posture change, greatly reducing the internal stress of the device caused by the left-right or front-back height difference during the test vehicle posture adjustment process, ensuring the stable position limiting of the test vehicle, and better adapting to the installation and fixation of test vehicles of different sizes;

[0018] Second, the floating measurement function is realized: the present invention can realize the wind tunnel simulation of the real driving state by improving the design of the floating support rod and utilizing the height change of the floating support rod, and can monitor the influence of the aerodynamic force on the vehicle body posture through the sliding potentiometer arranged on the floating support rod;

[0019] 3. Compact structure and little influence on wind tunnel flow field: The device of the present invention has a compact structure, small size and a rounded external shape, which greatly reduces the influence on the wind tunnel flow field. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1a It is a schematic diagram of the connection and installation structure of the present invention and the test vehicle;

[0021] Figure 1b for Figure 1a A side view structural schematic diagram of;

[0022] Figure 2a It is a schematic diagram of the connection structure between the clamping device and the floating support rod in the present invention;

[0023] Figure 2b for Figure 2a A schematic cross-sectional structure diagram of ;

[0024] Figure 3a It is a schematic diagram of the structure of the clamping device in the present invention;

[0025] Figure 3b for Figure 3a AA cross-sectional diagram of ;

[0026] Figure 4 It is a schematic diagram of the function of the rotating shaft of the clamping device in the present invention;

[0027] Explanation of the markings in the figure: 1. Clamping device, 2. Floating support mechanism, 3. Test vehicle, 4. Test section ground, 5. Six-component force balance, 1-1. Moving position chuck, 1-2. Fixed position chuck, 1-3. Rotating shaft, 1-4. Y-type support, 1-5. Locking block, 2-1. Floating rod, 2-2. Fixed rod, 2-3. Limit pin, 2-4. Sliding potentiometer. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example

[0030] like Figure 1a and Figure 1b As shown, a floating model limiting device for automobile wind tunnel force test is composed of a clamping device 1 and a floating support mechanism 2. Figure 2a , Figure 2b , Figure 3a and Figure 3b As shown, the clamping device 1 includes a movable position clamp 1-1, a fixed position clamp 1-2, a rotating shaft 1-3, a Y-shaped support 1-4 and a locking block 1-5; the floating support mechanism 2 includes a fixed rod 2-2 threadedly fixedly connected to the six-component force balance 5, a floating rod 2-1 that can slide up and down inside the fixed rod 2-2, a limit pin 2-3 installed on the fixed rod 2-2 and a sliding potentiometer 2-4 that can monitor the floating amount in real time.

[0031] In this embodiment, a threaded hole is opened on the movable clamp 1-1, which cooperates with the fixed clamp 1-2. The movable clamp 1-1 can be pulled to tighten and clamp the skirt or body of the test vehicle 3 with better rigidity through bolt tightening, so as to ensure the rigid connection between the clamping device 1 and the vehicle 3.

[0032] The movable position chuck 1-1 and the fixed position chuck 1-2 are connected to the Y-shaped support 1-4 through the rotating shaft 1-3. The two chucks can rotate freely around the rotating shaft 1-3 within a certain angle range, and most of the load is borne by the contact part between the Y-shaped support 1-4 and the movable position chuck 1-1 and the movable position chuck 1-2. A conical hole is provided at the lower end of the Y-shaped support 1-4, which cooperates with the upper conical surface at the upper end of the floating rod 2-1 to ensure the gap-free fit between the clamping device 1 and the floating support mechanism 2.

[0033] The locking block 1-5 is divided into two parts, inner and outer parts, and its upper end is hung on the lower edge of the Y-shaped support 1-4 through a guide groove. The locking block 1-5 and the floating rod 2-1 can be locked and loosened by bolts. The inner side of the locking block 1-5 is a conical surface, which cooperates with the lower conical surface at the upper end of the floating rod 2-1 to maintain the rigid connection between the floating rod 2-1 and the clamping device 1 when locking.

[0034] The floating rod 2-1 is provided with a vertical floating guide groove, which cooperates with the limit pin 2-3 on the fixed rod 2-2 to ensure that the floating rod 2-1 can slide up and down safely inside the fixed rod 2-2, and the floating amount is not less than 60mm. The limit pin 2-3 can also directly lock the floating rod 2-1. At this time, the test vehicle 3 is rigidly connected to the six-component force balance 5, and the body posture will not be changed by the influence of aerodynamic force.

[0035] The sliding potentiometer 2-4 installed on the fixed rod 2-2 has a sliding part connected to the lower end of the fixed rod 2-2. The data signal output by the sliding potentiometer 2-4 can be converted into the corresponding up and down floating distance of the floating rod 2-1. Therefore, the sliding potentiometer 2-4 can output the electrical signal of the real-time floating amount of the floating rod 2-1, which can be converted into the real-time change amount of the vehicle body posture height according to the geometric relationship.

[0036] The specific working principle of this technical solution is: after the clamping device 1 clamps the test vehicle 3, the floating rod 2-1 can be prevented from floating through the limit pin 2-3. At this time, the test vehicle 3 is rigidly connected to the balance, and the body posture remains unchanged. However, when the posture is adjusted during the test preparation or test process, the movable clamp 1-1 and the fixed clamp 1-2 can rotate around the rotation axis 1-3. Figure 4 As shown, the solid line in the figure is the original clamping state of the test vehicle 3 with a wheelbase of 3000mm. When the front body posture height remains unchanged and only the rear body posture height rises by 60mm, the test vehicle and the present invention become the dotted line state. If there is no rotating shaft 1-3, the support rod mechanism 2 will be displaced to the dotted line position in the figure, and the front and rear support rods will produce a maximum displacement of about 5mm in the X direction. The internal stress of the entire device will increase greatly, which will cause the clamping force of the device to decrease or even fall off. After adding the rotating shaft 1-3, the displacement of the floating support rod mechanism 2 (the distance between the dotted line and the solid line) is only 0.5mm, which greatly improves the adaptability of the device and ensures the stable limit of the test vehicle.

[0037] When the floating rod 2-1 can float up and down, the limit pin 2-3 only serves to limit the floating amount. At this time, the test vehicle 3 and the six-component force balance 5 are no longer fixedly connected, and the body posture can change with the change of aerodynamic lift during the test, realizing the wind tunnel simulation test of the real driving state, and the floating rod 2-1 moves synchronously with the sliding potentiometer 2-4, and the signal output of the sliding potentiometer 2-4 can be converted into the posture change amount of the test vehicle 3 affected by the aerodynamic force.

[0038] In summary, this technical solution proposes a floating model limit device for automobile wind tunnel force measurement test, which can not only adapt to various vehicle models and improve the stability of the test model limit, but also provide a floating measurement method that is more in line with the actual driving state. This technical solution can replace the fixed metal rod model limit fixture of the automobile wind tunnel force measurement platform, realize and measure the real posture (body height) change of the automobile model under the action of aerodynamic force, and is safe and reliable after wind tunnel experiments. The up and down floating displacement data is accurate, which provides a feasible solution for automobile wind tunnel research to measure the aerodynamic characteristics of real automobiles.

Claims

1. A floating model limiter for automobile wind tunnel force test, characterized in that: The invention comprises a clamping device (1) provided with a rotating shaft (1-3), the top of the clamping device (1) is connected to a test vehicle (3), the bottom of the clamping device (1) is connected to a floating support mechanism (2) with variable height, the floating support mechanism (2) is connected to a six-component force balance (5), the floating support mechanism (2) is connected to a processor, the floating support mechanism (2) outputs its own height floating distance data to the processor, and the processor converts the attitude change amount of the test vehicle (3) caused by the influence of aerodynamic force according to the height floating distance data of the floating support mechanism (2); The clamping device (1) comprises a movable clamp (1-1) and a fixed clamp (1-2) sleeved on a rotating shaft (1-3); the movable clamp (1-1) and the fixed clamp (1-2) can rotate around a rotation shaft; the rotating shaft (1-3) is connected to a Y-shaped support (1-4); the Y-shaped support (1-4) is connected to a floating support mechanism (2) via two symmetrically arranged locking blocks (1-5); The floating support mechanism (2) comprises a fixed rod (2-2) connected to the six-component force balance (5), and a floating rod (2-1) that can slide up and down is installed in the fixed rod (2-2); The fixed rod (2-2) is provided with a limit pin (2-3) for limiting the sliding displacement of the floating rod (2-1) and a sliding potentiometer (2-4) for detecting the upward and downward sliding distance of the floating rod (2-1); The upper end of the floating rod (2-1) is provided with an upper conical surface and a lower conical surface, the upper conical surface is matched and connected with a conical hole provided at the lower end of the Y-shaped support (1-4), and the inner wall of the locking block (1-5) is matched and connected with the lower conical surface at the upper end of the floating rod (2-1), so as to maintain the rigid connection between the floating rod (2-1) and the clamping device (1) when locking.

2. A floating model limiting device for automobile wind tunnel force test according to claim 1, characterized in that: The movable clamp (1-1) is provided with a threaded hole that matches the fixed clamp (1-2), and a bolt is installed in the threaded hole. The movable clamp (1-1) can be pulled to tighten and clamp the test vehicle (3) by tightening the bolt, thereby ensuring a rigid connection between the clamping device (1) and the test vehicle (3).

3. The floating model limiting device for automobile wind tunnel force test according to claim 1 is characterized in that: The floating rod (2-1) is provided with a vertical guide groove matched with the limit pin (2-3) to ensure that the floating rod (2-1) can slide up and down safely inside the fixed rod (2-2).

4. The floating model limiting device for automobile wind tunnel force test according to claim 1 is characterized in that: The sliding portion of the sliding potentiometer (2-4) is connected to the fixed rod (2-2).

5. The floating model limiting device for automobile wind tunnel force test according to claim 1 is characterized in that: The upper end of the locking block (1-5) is hung on the lower edge of the Y-shaped support (1-4), and the two locking blocks (1-5) are connected by bolts, and are locked or opened by the bolts.

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