Piston rod position detection device

Abstract

The utility model discloses a piston rod position detection device which comprises a detection mark arranged at a to-be-detected position on the periphery of a piston rod and a photoelectric detection mechanism facing the periphery of the piston rod. The spectral reflectivity of the detection mark is different from that of the periphery of the piston rod; the light detection mechanism comprises a light emitting unit and a light receiving unit; the light emitting unit is used for emitting detection light towards the periphery of the piston rod, and the light receiving unit is used for receiving the detection light reflected by the periphery of the piston rod or a detection mark; the light receiving unit is connected with a data processing unit; the data processing unit is connected to the light emitting unit through the light source control unit; according to the utility model, the light detection mechanism emits the detection light and receives the reflected light reflected by the detection mark or the periphery of the piston rod, and when the spectral reflectivity of the reflected light changes, the piston rod is considered to move to the preset position, so that the detection of the preset position of the piston rod is realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of piston rod position detection, and in particular relates to a piston rod position detection device. Background Art

[0002] The piston rod is used in the hydraulic cylinder and the pneumatic cylinder motion actuator. It is a moving part with frequent movements and high technical requirements. In actual use, it is usually necessary to detect the position of the piston rod relative to the cylinder barrel of the hydraulic cylinder or the pneumatic cylinder to achieve the positioning of the engineering equipment.

[0003] Traditionally, the position of the piston rod is detected by using a magnetostrictive displacement sensor, which converts the displacement into an electrical signal for monitoring the position of the piston rod.

[0004] However, magnetostrictive displacement sensors use magnetostrictive materials, which results in a high cost. The selling price is usually between 2,000 and 3,000 yuan. This high price means that they are only used in high-priced oil or gas cylinders with high precision requirements, and it is difficult to use them on a large scale in low-priced oil cylinders. In addition, when installing magnetostrictive sensors, detection components need to be installed inside the piston rod, which will damage the internal structure of the piston rod and even affect the service life of the piston rod. Utility Model Content

[0005] The utility model aims to provide a piston rod position detection device, which can realize the detection of the predetermined position of the piston rod without destroying the internal structure of the piston rod.

[0006] The utility model adopts the following technical scheme: a piston rod position detection device, comprising a detection mark set at a position to be detected on the periphery of the piston rod and a light detection mechanism facing the periphery of the piston rod; the spectral reflectivity of the detection mark is different from the spectral reflectivity of the periphery of the piston rod;

[0007] The optical detection mechanism includes a light emitting unit and a light receiving unit; the light emitting unit is used to emit detection light toward the periphery of the piston rod, and the light receiving unit is used to receive the detection light reflected by the periphery of the piston rod or the detection mark;

[0008] The light receiving unit is connected to a data processing unit;

[0009] The data processing unit is connected to the light emitting unit through the light source control unit.

[0010] Further, the detection mark is a light reflecting layer on the outer circumference of the piston rod.

[0011] Further, the light reflecting layer is arranged along the circumference of the outer periphery of the piston rod;

[0012] The light reflecting layer is an arc-shaped layer or a circular layer.

[0013] Furthermore, the number of detection identifiers is at least one.

[0014] Further, the light emitting unit and the light receiving unit are located on the same cross section of the piston rod.

[0015] Furthermore, the piston rod position detection device is installed on the cylinder barrel corresponding to the piston rod.

[0016] The beneficial effect of the utility model is that the utility model emits detection light through the light detection mechanism and receives reflected light reflected by the detection mark or the outer periphery of the piston rod. When the spectral reflectivity of the reflected light changes, it is considered that the piston rod has moved to a predetermined position, thereby realizing the detection of the predetermined position of the piston rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a piston rod position detection device according to an embodiment of the utility model;

[0018] Figure 2 It is a structural schematic diagram of a piston rod position detection device according to an embodiment of the utility model.

[0019] Wherein: 10. light emitting unit; 11. light source; 12. collimating lens;

[0020] 20. Light receiving unit; 21. Photodetector; 22. Focusing lens;

[0021] 30. Detection mark; 40. Piston rod; 60. Data processing unit; 70. Light source control unit; 80. Signal amplification unit; 90. Filter processing unit; 100. Cable. DETAILED DESCRIPTION

[0022] The utility model is described in detail below with reference to the accompanying drawings and specific implementation modes.

[0023] Oil cylinders and pneumatic cylinders are widely used in various industrial machinery and equipment. Position / displacement detection is used to monitor and control oil cylinders and pneumatic cylinders. By measuring the displacement of the piston rod, the working status of the system can be monitored in real time, and it can be determined whether the oil cylinders and pneumatic cylinders are working normally and whether there are any faults. This is very important for the safe operation of the equipment and timely maintenance and repair.

[0024] The position / displacement detection of oil and gas cylinders can also realize automatic control and improve production efficiency and quality. With the continuous advancement of technology, the functions and applications of displacement sensors for oil and gas cylinders will continue to expand, bringing more convenience and benefits to industrial production.

[0025] Most of the traditional high-precision displacement detection of oil cylinders and air cylinders uses magnetostrictive displacement sensors to convert displacement into electrical signals for monitoring and control of oil cylinders and air cylinders. Magnetostrictive displacement sensors are high-precision displacement measurement sensors developed based on the magnetostrictive principle. This type of sensor is expensive and complex to install, and has been used in some hydraulic cylinders with high precision requirements.

[0026] However, for the zero-position detection of conventional oil cylinders and air cylinders (such as the oil cylinder in the automobile bogie needs to detect the tire steering angle), if a magnetostrictive displacement sensor is used, the cost of the oil cylinder or air cylinder will be greatly increased (for example, the cost of an oil cylinder or air cylinder that costs tens of yuan will rise to several thousand yuan after installing a magnetostrictive sensor). This will result in the cost of oil cylinders and air cylinders being too high and difficult to promote on a large scale.

[0027] The utility model discloses a piston rod position detection device, such as Figure 1 and Figure 2 As shown, it includes a detection mark 30 set at a position to be detected on the periphery of the piston rod 40 and a light detection mechanism facing the periphery of the piston rod 40; the spectral reflectivity of the detection mark 30 is different from the spectral reflectivity of the periphery of the piston rod 40; the light detection mechanism includes a light emitting unit 10 and a light receiving unit 20; the light emitting unit 10 is used to emit detection light toward the periphery of the piston rod 40, and the light receiving unit 20 is used to receive the detection light reflected by the periphery of the piston rod 40 or the detection mark 30; the light receiving unit 20 is connected to the data processing unit 60; the data processing unit 60 is connected to the light emitting unit 10 through the light source control unit 70.

[0028] The utility model emits detection light through a light detection mechanism and receives reflected light reflected by a detection mark or the periphery of a piston rod. When the spectral reflectivity of the reflected light changes, it is considered that the piston rod has moved to a predetermined position, thereby realizing the detection of the predetermined position of the piston rod.

[0029] The light emitting unit 10 includes a light source 11 and a collimating lens 12. The light source 11 is used to generate one or more light sources to evenly illuminate the circumference of the piston rod 40 to be tested. The light source 11 emits a certain power of light, which is collimated into parallel light by the collimating lens 12, so that it is irradiated onto the detection mark 30 to form a certain size and uniform detection area. The wavelength of the light source can be selected according to the surface characteristics of the piston rod 40. The collimating lens 12 can provide a parallel light beam that meets the width of the detection mark 30.

[0030] In the embodiment of the utility model, the detection mark 30 is a circle of dark marks etched at the zero position or the middle position of the piston rod. The spectral reflectance of the detection mark 30 position and other positions of the piston rod 40 are different. The light receiving unit 20 receives the optical power signal with difference and converts it into an electrical signal. Moreover, the surface quality of the piston rod 40 after the detection mark 30 is set is the same as that of the piston rod 40 to ensure the normal movement of the piston rod 40.

[0031] Specifically, the light receiving unit 20 includes a focusing lens 22 and a photodetector 21. The light receiving unit 20 is used to receive the reflected light from the surface of the piston rod 40, obtain the optical power information of the reflected light, and convert it into an electrical signal.

[0032] The spectrum of the photodetector 21 is selected to have a wide band range, and its optical power intensity in the wide spectrum range is increased, thereby increasing the resolution of the reflection spectrum of the surface of the piston rod 40. The focusing lens 22 is used to converge the reflected light generated by the surface of the piston rod 40 and focus it on the photodetector 21. The surface of the focusing lens 22 is a high-polished surface, and the spot diameter at its focal length is smaller than the width of the detection mark 30, so that better resolution can be obtained.

[0033] The signal amplification unit 80 is connected to the filtering processing unit 90, and the filtering processing unit 90 is connected to the data processing unit 60. The electrical signal directly converted from the optical power signal is extremely weak and easily affected by noise. The weak signal of the light receiving unit 20 needs to be amplified and processed by the preamplifier circuit of the signal amplification unit 80. There is a difference in the strength of the electrical signal related to the zero position and other positions of the piston rod 40. The amplification factor needs to be adjusted so that it cannot be saturated at other positions, and the difference in the received voltage between other positions and the zero position is the largest, so as to further improve the resolution.

[0034] The filter processing circuit adopts a combination circuit of a first-level low-pass filter and a first-level high-pass filter, so that only signals within a specific frequency range can pass and be transmitted to the back-end processor. The specific frequency range is consistent with the frequency signal of the optical power modulation reflected by the surface of the piston rod 40, and can isolate the usual power supply noise frequency or the interference signal frequency of high-power electrical appliances, thereby improving the ability to resist electromagnetic interference.

[0035] After being processed by the signal amplification unit 80 and the filtering processing unit 90, the data transmission is sent to the data processing unit 60. When the piston rod reciprocates or stops, the reflected light intensity collected by the receiving end is different, and electrical signals with different characteristics can be obtained. In most cases, the signals collected by the light receiving unit 20 are the same. This is because the detection mark 30 is very small compared to the outer surface area of ​​the entire piston rod 40, so in most cases the electrical signals are close to the same value. When the electrical signal changes significantly, it means that the light signal detected at this time is reflected by the detection mark, resulting in a significant change in the electrical signal, and it can be determined that the piston rod 40 is located at the position to be detected.

[0036] In one embodiment, the detection mark 30 is a light reflection layer on the outer periphery of the piston rod 40, and the light reflection layer is arranged along the circumference of the outer periphery of the piston rod 40; the light reflection layer is an arc-shaped layer or a circular layer. Such an arrangement can make the reflection part of the light reflection layer located on the same cross section of the piston rod 40, thereby avoiding position errors caused by reflected light from different cross sections, thereby improving the detection accuracy.

[0037] In actual applications, there may be more than one position to be detected of the piston rod 40, so the number of the detection mark 30 is at least one, and the specific number is designed according to the actual application scenario.

[0038] The light emitting unit 10 and the light receiving unit 20 are located on the same cross section of the piston rod 40, so that the detection light and the reflected light are both on the same cross section of the piston rod 40, thereby achieving position correspondence with the detection mark 3, thereby improving the detection accuracy.

[0039] In the embodiment of the utility model, the piston rod position detection device is installed on the cylinder corresponding to the piston rod 40, and the axis of the piston rod position detection device and the axis of the piston rod 40 are perpendicular to each other.

[0040] like Figure 2 As shown, the piston rod position detection device of the utility model can be installed on the cylinder barrel, so that the detection light emitted by the light source 11 and the collimating lens 12 at the front end is directed toward the outer surface of the piston rod 40, and is arranged perpendicular to the normal line of the piston rod, so that one end is located in the cylinder barrel and the other end is exposed outside the cylinder barrel. Other components can be integrated on a PCBA, and the PCBA is connected to an external power supply and an indicating device through a cable 100.

Claims

1. A piston rod position detection device, characterized in that: It comprises a detection mark (30) arranged at a position to be detected on the periphery of a piston rod (40) and a light detection mechanism facing the periphery of the piston rod (40); the spectral reflectivity of the detection mark (30) is different from the spectral reflectivity of the periphery of the piston rod (40); The light detection mechanism comprises a light emitting unit (10) and a light receiving unit (20); the light emitting unit (10) is used to emit detection light toward the periphery of the piston rod (40), and the light receiving unit (20) is used to receive the detection light reflected by the periphery of the piston rod (40) or the detection mark (30); The light receiving unit (20) is connected to a data processing unit (60); The data processing unit (60) is connected to the light emitting unit (10) via a light source control unit (70).

2. A piston rod position detection device according to claim 1, characterized in that: The detection mark (30) is a light reflection layer on the outer periphery of the piston rod (40).

3. A piston rod position detection device as claimed in claim 2, characterized in that: The light reflecting layer is arranged along the circumference of the outer periphery of the piston rod (40); The light reflecting layer is an arc-shaped layer or a circular layer.

4. A piston rod position detection device as claimed in claim 2, characterized in that: The number of the detection mark (30) is at least one.

5. A piston rod position detection device according to any one of claims 2 to 4, characterized in that: The light emitting unit (10) and the light receiving unit (20) are located on the same cross section of the piston rod (40).

6. A piston rod position detection device as claimed in claim 5, characterized in that: The piston rod position detection device is installed on the cylinder barrel corresponding to the piston rod (40).

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