Motor vehicle detection line anti-cheating device

Abstract

The invention discloses a motor vehicle detection line anti-cheating device, and belongs to the technical field of motor vehicle detection lines, the motor vehicle detection line anti-cheating device comprises a detection assembly and further comprises a hollow circular truncated cone-shaped inner cylinder, a sealing bottom is arranged at the small-diameter end of the inner cylinder, and a dilution cheating prevention assembly is arranged on the outer surface of the inner cylinder; the outer part of the inner cylinder is provided with a tamper-proof cheating assembly, the assembly comprises an outer cylinder, the outer cylinder coaxially sleeves the outer part of the inner cylinder and is fixedly connected with the large-diameter end of the inner cylinder, and the inner surface of the outer cylinder is telescopically provided with a temperature sensor; the detection assembly comprises a detector, a detection probe and a contact switch, the detection probe is installed at the tail end of the deep-cheating-preventing assembly, and deep detection of the detection probe is achieved through the deep-cheating-preventing assembly; a driving assembly used for opening and closing the contact switch is arranged in the inner cylinder, and the deep cheating prevention assembly and the dilution cheating prevention assembly are synchronously driven through the driving assembly.

Description

Technical Field

[0001] The present invention relates to the technical field of motor vehicle inspection lines, and particularly to an anti-cheating device for motor vehicle inspection lines. Background Art

[0002] With the continuous improvement of environmental protection requirements, the detection of motor vehicle exhaust emissions has become one of the important means to control pollution emissions. At present, various motor vehicle inspection lines are widely deployed in vehicle inspection institutions to sample and analyze the pollutant components (such as CO, HC, NOx, etc.) in the exhaust gas to determine whether the vehicle meets the environmental protection standards.

[0003] However, there are various risks of being artificially intervened and bypassed in the actual application of the existing motor vehicle detection system. The main manifestations are as follows: Diluting exhaust gas for cheating: Some vehicle owners dilute the exhaust gas concentration by introducing air, water vapor, etc. into the exhaust pipe before detection, so as to reduce the detection value and avoid the environmental protection standards; Irregular insertion depth of the probe: The insertion depth of the detection probe directly affects the detection accuracy. Some people control the insertion depth too shallow or too deep, resulting in deviation of the detection result and even ineffective sampling.

[0004] In response to the above problems, although technical solutions such as setting air sealing rings, infrared induction displacement sensors, image recognition assistance, etc. have been proposed in the prior art, there are still problems such as complex structure, inconvenient installation, single or incomplete anti-cheating effect, etc. as a whole, and it is difficult to meet the dual requirements of accuracy and anti-cheating ability for current motor vehicle emission supervision.

[0005] Therefore, we propose an anti-cheating device for motor vehicle inspection lines. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides an anti-cheating device for motor vehicle inspection lines, which can effectively prevent various types of cheating behaviors during the detection process and significantly improve the reliability and accuracy of motor vehicle exhaust gas detection.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] An anti-cheating device for motor vehicle inspection lines includes a detection component, and also includes an inner cylinder in the shape of a hollow frustum. One end with a smaller diameter of the inner cylinder is provided with a bottom seal, and an anti-dilution cheating component is arranged on the outer surface of the inner cylinder;

[0009] An anti-tampering cheating component is arranged outside the inner cylinder. This component includes an outer cylinder, the outer cylinder is coaxially sleeved outside the inner cylinder and is fixedly connected to the end with a larger diameter of the inner cylinder, and a temperature sensor is telescopically arranged on the inner surface of the outer cylinder;

[0010] An anti-depth cheating component is provided on the bottom seal of the inner cylinder. The detection component includes a detector, a detection probe, and a contact switch. The detection probe is installed at the end of the anti-depth cheating component, and the in-depth detection of the detection probe is realized through the anti-depth cheating component.

[0011] The detector is installed on the outer surface of the outer cylinder. The contact switch is installed on the inner bottom of the inner cylinder and is signal-connected between the detector and the detection probe respectively, and the signal connection between the detection probe and the detector is realized through the contact switch.

[0012] A driving component for opening and closing the contact switch is arranged inside the inner cylinder, and the anti-depth cheating component and the anti-dilution cheating component are synchronously driven through the driving component.

[0013] As a preferred solution of the anti-cheating device for a motor vehicle detection line according to the present invention, wherein: the anti-dilution cheating component includes a sealing air cushion, an inflation port, and a pressure sensor. An installation groove is formed on the outer circumferential surface of the inner cylinder, and the sealing air cushion is connected to the inside of the installation groove. The inflation port and the pressure sensor are both arranged on the bottom seal surface of the inner cylinder.

[0014] As a preferred solution of the anti-cheating device for a motor vehicle detection line according to the present invention, wherein: a guiding cylinder is coaxially connected to the inner bottom of the inner cylinder. An airbag is arranged between the outer circumferential surface of the guiding cylinder and the inner circumferential surface of the inner cylinder. The airbag is connected to the sealing air cushion through a pipeline, and the inflation and deflation of the sealing air cushion are controlled through the airbag.

[0015] As a preferred solution of the anti-cheating device for a motor vehicle detection line according to the present invention, wherein: a guiding hole is axially formed on the outer surface of the guiding cylinder. A pressing plate is arranged at the rear end of the airbag. A connecting frame is arranged inside the inner cylinder. The outer end of the connecting frame penetrates through the guiding hole and is fixedly connected to the pressing plate, and the airbag is compressed through the pressing plate.

[0016] As a preferred solution of the anti-cheating device for a motor vehicle detection line according to the present invention, wherein: the driving component includes a lead screw, a nut sleeve, and a control ring. The lead screw is rotatably arranged on the inner bottom of the inner cylinder. The nut sleeve is screwed on the outer surface of the lead screw. The control ring corresponds to the contact switch and is fixedly connected to the nut sleeve. The opening and closing of the contact switch are controlled through the forward and backward movement of the control ring, and the connecting frame is telescopically connected to the control ring in the front and back directions.

[0017] As a preferred solution of the anti-cheating device for a motor vehicle detection line according to the present invention, wherein: a connecting rod is connected to the rear end of the control ring. The connecting rod movably penetrates through the connecting frame, and a fixing spring is connected between the end of the connecting rod and the connecting frame.

[0018] As a preferred embodiment of the anti-cheating device for a motor vehicle inspection line according to the present invention, the following applies: The anti-depth-cheating component includes a push rod, which is connected to the front end face of a screw sleeve. The other end of the push rod penetrates through an inner cylinder movably, and a detection probe is installed at the end of the push rod.

[0019] As a preferred embodiment of the anti-cheating device for a motor vehicle inspection line according to the present invention, the following applies: A protective cover for accommodating the detection probe is connected to the sealed bottom surface of the inner cylinder. A protective shield is sleeved outside the protective cover, and both the inflation port and the pressure sensor are located between the protective cover and the protective shield.

[0020] As a preferred embodiment of the anti-cheating device for a motor vehicle inspection line according to the present invention, the following applies: A ring cover is covered and arranged at the open end of the inner cylinder. A return spring is connected between the ring cover and the guiding cylinder. The end of the screw rod is connected with a turning handle, and the turning handle is located in the central hole of the ring cover.

[0021] As a preferred embodiment of the anti-cheating device for a motor vehicle inspection line according to the present invention, the following applies: A cleaning brush is arranged around the inner side wall of the open end of the outer cylinder, and handrails are connected to the outer side walls at both ends of the outer cylinder.

[0022] Compared with the prior art, the beneficial effects that the present invention can achieve are as follows:

[0023] The present invention provides an anti-cheating device for a motor vehicle inspection line with a novel structure and composite functions, which can effectively solve various cheating problems such as dilution, tampering, and deep forgery existing in the current motor vehicle exhaust gas detection process, greatly improve the authenticity of detection data, and achieve the following key beneficial effects through the coordinated cooperation of multiple structures and modules:

[0024] First of all, the device adopts a double-layer structure of an outer cylinder and an inner cylinder. The outer cylinder plays an isolation and protection role, preventing external interference during the detection process, and monitors illegal temperature rises through a temperature sensor to prevent artificial tampering with the detection environment; the inner cylinder, as the core component, integrates multiple anti-cheating functions such as anti-dilution, anti-depth, and anti-tampering to ensure that the detection probe operates in a sealed and safe environment;

[0025] Secondly, in terms of anti-dilution, through the linkage control of the sealing air cushion, the inflation port and the pressure sensor, the sealed detection of the exhaust gas path is realized. Once abnormal air pressure occurs, the dilution behavior can be immediately identified. In terms of anti-depth cheating, through the linkage structure of the guiding cylinder, the push rod and the detection probe, the insertion depth is accurately controlled, and combined with the airbag feedback and the contact switch signal, the real-time monitoring and correction of the probe position are realized, effectively preventing deep forgery;

[0026] Thirdly, the drive assembly uses a screw mechanism with a screw sleeve and a control ring to achieve precise control of the probe movement, while linking the contact switch and the connecting frame to compress the airbag, enhancing the linkage and intelligent response capabilities of the system and improving the automation level of the entire detection process;

[0027] In summary, through structural integration and multi-module collaboration, the anti-cheating capability and detection accuracy of the motor vehicle emission detection system have been comprehensively improved. It can adapt to complex and changeable detection environments and ensure the fairness and efficiency of environmental protection testing work. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a schematic diagram of the structure of an anti-cheating device for a motor vehicle inspection line.

[0029] Figure 2 The figure is a schematic diagram of a screw rod of an anti-cheating device for a motor vehicle inspection line.

[0030] Figure 3 This is a schematic diagram of the inner cylinder of an anti-cheating device for a motor vehicle inspection line.

[0031] Figure 4 The present invention is a schematic diagram of a guide tube of an anti-cheating device for a motor vehicle inspection line.

[0032] Figure 5 The figure is a schematic diagram of a control loop of an anti-cheating device for a motor vehicle inspection line.

[0033] Figure 6 The figure is a schematic diagram of a connecting frame of an anti-cheating device for a motor vehicle inspection line.

[0034] Among them: 1. Inner cylinder; 2. Detector; 3. Detection probe; 4. Outer cylinder; 5. Temperature sensor; 6. Sealing air cushion; 7. Inflating port; 8. Pressure sensor; 9. Protective cover; 10. Protective cover; 11. Handrail; 12. Cleaning brush; 13. Guide cylinder; 14. Screw rod; 15. Turn handle; 16. Ring cover; 17. Reset spring; 18. Mounting groove; 19. Guide hole; 20. Pressure plate; 21. Air bag; 22. Push rod; 23. Contact switch; 24. Screw sleeve; 25. Control ring; 26. Connecting frame; 27. Connecting rod; 28. Fixed spring. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0036] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those specifically described herein, and those skilled in the art may make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0037] Secondly, as used herein, an "embodiment" or "an embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The appearances of "in an embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that are mutually exclusive of other embodiments.

[0038] Embodiment

[0039] Please refer to Figures 1 to 6 As shown, the present invention provides an anti-cheating device for a motor vehicle detection line, including a detection component, and further including an inner cylinder 1 in the shape of a hollow frustum. One end with a smaller diameter of the inner cylinder 1 is provided with a bottom seal, and an anti-dilution cheating component is arranged on the outer surface of the inner cylinder 1;

[0040] The anti-dilution cheating component includes a sealing air cushion 6, an inflation port 7, and a pressure sensor 8. An installation groove 18 is formed on the outer circumferential surface of the inner cylinder 1, and the sealing air cushion 6 is connected to the inside of the installation groove 18. Both the inflation port 7 and the pressure sensor 8 are arranged on the bottom surface of the inner cylinder 1;

[0041] A guiding cylinder 13 is coaxially connected to the inner bottom of the inner cylinder 1. An airbag 21 is arranged between the outer circumferential surface of the guiding cylinder 13 and the inner circumferential surface of the inner cylinder 1. The airbag 21 is connected to the sealing air cushion 6 through a pipeline to control the inflation and deflation of the sealing air cushion 6. A guiding hole 19 is axially formed on the outer surface of the guiding cylinder 13. A pressing plate 20 is arranged at the rear end of the airbag 21. A connecting frame 26 is arranged inside the inner cylinder 1. The outer end of the connecting frame 26 penetrates through the guiding hole 19 and is fixedly connected to the pressing plate 20 to compress the airbag 21 through the pressing plate 20;

[0042] An anti-tampering cheating component is arranged outside the inner cylinder 1. This component includes an outer cylinder 4. The outer cylinder 4 is coaxially sleeved outside the inner cylinder 1 and is fixedly connected to the end with a larger diameter of the inner cylinder 1. A temperature sensor 5 is telescopically arranged on the inner surface of the outer cylinder 4;

[0043] An anti-depth cheating component is arranged on the bottom seal of the inner cylinder 1. The detection component includes a detector 2, a detection probe 3, and a contact switch 23. The detection probe 3 is installed at the end of the anti-depth cheating component to achieve in-depth detection of the detection probe 3 through the anti-depth cheating component;

[0044] The detector 2 is installed on the outer surface of the outer cylinder 4. The contact switch 23 is installed on the inner bottom of the inner cylinder 1 and is signal-connected to the detector 2 and the detection probe 3 respectively, so as to realize the signal connection between the detection probe 3 and the detector 2 through the contact switch 23;

[0045] A driving assembly for opening and closing the contact switch 23 is arranged inside the inner cylinder 1, and the anti-depth cheating assembly and the anti-dilution cheating assembly are synchronously driven by the driving assembly;

[0046] The driving assembly includes a lead screw 14, a nut sleeve 24 and a control ring 25. The lead screw 14 is rotatably arranged on the inner bottom of the inner cylinder 1. The nut sleeve 24 is screwed on the outer surface of the lead screw 14. The control ring 25 corresponds to the contact switch 23 and is fixedly connected to the nut sleeve 24. The opening and closing of the contact switch 23 is controlled by the forward and backward movement of the control ring 25. A connecting frame 26 is telescopically connected to the control ring 25 in the front and back directions. A connecting rod 27 is connected to the rear end of the control ring 25. The connecting rod 27 penetrates through the connecting frame 26 movably. A fixing spring 28 is connected between the end of the connecting rod 27 and the connecting frame 26;

[0047] The anti-depth cheating assembly includes a push rod 22. The push rod 22 is connected to the front end face of the nut sleeve 24. The other end of the push rod 22 penetrates through the inner cylinder 1 movably. The detection probe 3 is installed at the end of the push rod 22. A protective cover 9 for accommodating the detection probe 3 is connected to the sealed bottom surface of the inner cylinder 1. A protective housing 10 is sleeved outside the protective cover 9. The inflation port 7 and the pressure sensor 8 are both located between the protective cover 9 and the protective housing 10;

[0048] A ring cover 16 is covered on the open end of the inner cylinder 1. A return spring 17 is connected between the ring cover 16 and the guide cylinder 13. The end of the lead screw 14 is connected with a turning handle 15. The turning handle 15 is located in the central hole of the ring cover 16. A cleaning brush 12 is arranged around the inner side wall of the open end of the outer cylinder 4. Armrests 11 are connected to the outer side walls at both ends of the outer cylinder 4.

[0049] The anti-cheating device for the motor vehicle detection line of the present invention constructs a complete detection closed-loop process through the coordinated cooperation of multiple components, and can effectively prevent various human cheating behaviors in the process of exhaust gas detection. The specific working process is as follows:

[0050] I. Initial preparation stage

[0051] The detection device is in the standby state. The probe is stored in the protective cover 9 of the inner cylinder 1 to avoid pollution or accidental touch; the control system is initialized, and the lead screw 14, the nut sleeve 24, the push rod 22, etc. are in the origin position; the sealing air cushion 6 is not inflated, and the exhaust pipe interface remains open; the temperature sensor 5 on the outer cylinder 4 is started to monitor the surrounding temperature in real time.

[0052] The advantages of this step are as follows: preventing the probe from being exposed for a long time and extending its service life; monitoring the ambient temperature in real time to enable early warning of external abnormal interventions; and the system being in a stable state, which is conducive to quickly starting the detection process.

[0053] II. Device positioning and sealing preparation

[0054] The tester aligns the device with the tail of the motor vehicle exhaust pipe and uses the armrest 11 to assist in stable positioning; starts the drive assembly, and the screw rod 14 rotates to drive the nut sleeve 24, the push rod 22, and the control ring 25 to move forward; the control ring 25 drives the connecting frame 26 to move forward, compressing the airbag 21; after the airbag 21 is inflated, it is connected to the sealing air cushion 6 through a pipeline, causing it to expand and block the exhaust pipe interface; the pressure sensor 8 monitors the internal pressure of the motor vehicle exhaust pipe to determine whether the sealing standard is met.

[0055] The advantages of this step are as follows: accurately achieving mechanical sealing of the exhaust pipe opening, preventing the dilution of tail gas before entering the probe; the pressure feedback mechanism can automatically judge the sealing effect and eliminate detection errors caused by poor sealing; combining physical airtightness and intelligent perception to enhance the anti-dilution cheating ability.

[0056] III. Probe insertion and depth control

[0057] After the sealing is completed, continue to control the screw rod 14 to push the nut sleeve 24; the push rod 22 and the detection probe 3 connected to its front end move along the guide tube 13 and are inserted into the exhaust pipe; after the probe is inserted to the set depth, the contact switch 23 at the bottom is triggered to send a depth-in-place signal; if the probe does not reach the predetermined position, detection cannot be performed.

[0058] The advantages of this step are as follows: dual control of mechanical limit + electrical signal feedback effectively prevents cheating behavior of inserting too shallow; improving the consistency of the insertion of the detection probe 3 to ensure the representativeness and reliability of tail gas sampling; reducing the possibility of human intervention and improving the detection level.

[0059] IV. Safety protection and monitoring during the detection process

[0060] After the probe is inserted in place, the detector 2 starts to sample the tail gas components; the temperature sensor 5 installed on the inner wall of the outer cylinder 4 continuously detects the detection ambient temperature; if the temperature changes abnormally (such as external artificial heating), the detection is immediately aborted; all control and sensor lines are set in a sealed cylinder to prevent external physical contact and tampering.

[0061] The advantages of this step are as follows: achieving accurate identification and real-time response to illegal heating interference behaviors; ensuring that the detection data is collected under real environmental conditions; the overall sealed structure enhances the anti-interference and anti-tampering capabilities of the system and guarantees the detection safety.

[0062] V. Sampling end and reset

[0063] After the detection is completed, the control system rotates the lead screw 14 in the reverse direction; the push rod 22 and the probe retract into the inner cylinder 1 and enter the protective cover 9; the airbag 21 is depressurized, the sealing air cushion 6 retracts, and the sealed state is released; the whole device returns to the initial state to prepare for the next detection.

[0064] The advantages of this step are as follows: automatic reset, improving operation convenience and detection efficiency; the probe protective cover 9 protects the sampling head from contamination or damage, extending the service life of the equipment; the overall process is designed in a closed loop, improving the operation stability and reliability of the equipment.

[0065] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An anti-cheating device for a motor vehicle detection line, comprising a detection component, characterized in that: It further includes an inner cylinder (1) in the shape of a hollow frustum of a cone. One end with a smaller diameter of the inner cylinder (1) is provided with a bottom seal, and an anti-dilution cheating component is arranged on the outer surface of the inner cylinder (1); An anti-tampering cheating component is arranged outside the inner cylinder (1). This component includes an outer cylinder (4). An anti-depth cheating component is arranged on the bottom seal of the inner cylinder (1). The detection component includes a detector (2), a detection probe (3) and a contact switch (23); The detection probe (3) is installed at the end of the anti-depth cheating component. The detection probe (3) is deeply detected through the anti-depth cheating component. The detector (2) is installed on the outer surface of the outer cylinder (4). The contact switch (23) is installed on the inner bottom of the inner cylinder (1) and is signal-connected between the detector (2) and the detection probe (3) respectively. The signal connection between the detection probe (3) and the detector (2) is realized through the contact switch (23); A driving component for opening and closing the contact switch (23) is arranged inside the inner cylinder (1). The anti-depth cheating component and the anti-dilution cheating component are synchronously driven through the driving component.

2. The anti-cheating device for a motor vehicle inspection line according to claim 1, characterized in that: The anti-dilution cheating component includes a sealing air cushion (6), an air inlet (7) and a pressure sensor (8). An installation groove (18) is formed on the outer circumferential surface of the inner cylinder (1). The sealing air cushion (6) is connected inside the installation groove (18). Both the air inlet (7) and the pressure sensor (8) are arranged on the bottom surface of the inner cylinder (1).

3. The anti-cheating device for a motor vehicle inspection line according to claim 2, wherein: A guiding cylinder (13) is coaxially connected to the inner bottom of the inner cylinder (1). An airbag (21) is arranged between the outer circumferential surface of the guiding cylinder (13) and the inner circumferential surface of the inner cylinder (1). The airbag (21) is connected to the sealing air cushion (6) through a pipeline. The inflation and deflation of the sealing air cushion (6) are controlled through the airbag (21).

4. The anti-cheating device for a motor vehicle inspection line according to claim 3, wherein: A guiding hole (19) is axially formed on the outer surface of the guiding cylinder (13). A pressing plate (20) is arranged at the rear end of the airbag (21). A connecting frame (26) is arranged inside the inner cylinder (1). The outer end of the connecting frame (26) penetrates through the guiding hole (19) and is fixedly connected to the pressing plate (20). The airbag (21) is compressed through the pressing plate (20).

5. An anti-cheating device for a motor vehicle inspection line according to claim 4, characterized in that: The driving component includes a lead screw (14), a nut sleeve (24) and a control ring (25). The lead screw (14) is rotatably arranged on the inner bottom of the inner cylinder (1). The nut sleeve (24) is screwed on the outer surface of the lead screw (14). The control ring (25) corresponds to the contact switch (23) and is fixedly connected to the nut sleeve (24). The opening and closing of the contact switch (23) are controlled through the forward and backward movement of the control ring (25). The connecting frame (26) is connected to the control ring (25) in a telescopic manner in the front and back directions.

6. The anti-cheating device for a motor vehicle inspection line according to claim 5, characterized in that: A connecting rod (27) is connected to the rear end of the control ring (25). The connecting rod (27) movably penetrates through the connecting frame (26). A fixing spring (28) is connected between the end of the connecting rod (27) and the connecting frame (26).

7. An anti-cheating device for a motor vehicle inspection line according to claim 5, characterized in that: The anti-depth cheating component includes a push rod (22), the push rod (22) is connected to the front end face of the screw sleeve (24), the other end of the push rod (22) movably penetrates the inner cylinder (1), and the detection probe (3) is installed at the end of the push rod (22).

8. A vehicle inspection line anti-cheating device according to claim 2, characterized in that: A protective cover (9) for accommodating the detection probe (3) is connected to the bottom sealing surface of the inner cylinder (1), a protective housing (10) is sleeved outside the protective cover (9), and the inflation port (7) and the pressure sensor (8) are both located between the protective cover (9) and the protective housing (10).

9. An anti-cheating device for a motor vehicle inspection line according to claim 5, characterized in that: A ring cover (16) is covered and arranged at the open end of the inner cylinder (1), a return spring (17) is connected between the ring cover (16) and the guide cylinder (13), the end of the lead screw (14) is connected with a turning handle (15), and the turning handle (15) is located in the central hole of the ring cover (16).

10. A vehicle inspection line anti-cheating device according to claim 1, characterized in that: The outer cylinder (4) is coaxially sleeved outside the inner cylinder (1) and is fixedly connected to the end with a larger diameter of the inner cylinder (1), a temperature sensor (5) is telescopically arranged on the inner surface of the outer cylinder (4), a cleaning brush (12) is arranged around the inner side wall of the open end of the outer cylinder (4), and handrails (11) are connected and arranged on the outer side walls at both ends of the outer cylinder (4).

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