Single-channel position detection device
By setting a single-channel position detection device on the camshaft with characteristic position points, the camshaft position is identified by a single position switch and pulse signal, the problems of complex structure and high cost in the prior art are solved, and the accurate judgment of multiple position points is achieved.
Patent Information
- Application Number
- CN202422263743.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-15
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-09-15
AI Technical Summary
In the prior art, the camshaft position detection device has a complex structure and is costly, making it difficult to accurately identify multiple functional points, especially when a single position switch is used, three or more position points cannot be distinguished.
A single-channel position detection device is adopted to set characteristic position points of a specific width on the position point structure, a single position switch is used to identify the characteristic position points, and the absolute position of the camshaft is determined in combination with the pulse signal, so as to achieve multi-position judgment.
Eliminates the need to increase the number of position switches and rotary encoder, simplifies the structure, reduces costs, and improves the accuracy and reliability of position detection.
Smart Images
Figure CN223050615U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a position detection device, in particular to a position detection device corresponding to a camshaft. Background Art
[0002] The camshaft can convert the rotational motion into specific mechanical actions through cam plates, thereby realizing corresponding mechanical functions. Several functional points are usually set on the camshaft. During the working process, it is necessary to accurately identify the corresponding positions and perform corresponding actions according to the design requirements. Taking the strapping machine core as an example, there are usually functional points such as zero position, tape-return position, strapping position, cooling position, etc. on the cam structure of the strapping machine core.
[0003] When the camshaft rotates to the zero position and stops, the strapping machine core is in the initial state, and at this time, the tape feeding operation can be performed; when the camshaft rotates to the tape-return position and stops, the strapping machine core can perform the tape-return operation, and so on. From the above description, it can be seen that during the rotation of the camshaft, the controller needs to accurately identify the above-mentioned functional points in order to perform corresponding operations. In the prior art, the main methods for identifying the current position are setting position sensors and using rotary encoders. Although the rotary encoder has high precision, due to its high cost and relatively complex control logic, it is usually only used in applications with high precision. Another commonly used method is to use position switch sensors such as slot-type photoelectric switches, proximity switches, and limit switches to obtain the current position information.
[0004] A single position switch only has two states: on and off. When performing motion detection, there will be two types of position points: from off to on and from on to off. Therefore, at most two position points can be identified through the signal transition state. When the number of position points exceeds 2, it is impossible to distinguish only relying on the signal state.
[0005] In the prior art, for a camshaft that needs to determine 3 or more position points, two or more position switches need to be used. Although this solution can solve the problem, using multiple position switches increases the cost, and at the same time increases the complexity of the device, thereby increasing the risk of failure.
[0006] Based on the above analysis, it can be seen that the prior art solution using multiple position switches has the defects of high cost and complex system. Summary of the Invention
[0007] In order to overcome the deficiencies of the prior art, the present utility model proposes a single-channel position detection device. This device only needs to set one position switch, and a plurality of position points are provided on the position point structure member. By detecting the position points with a specific width feature, the absolute position in the position point structure member can be determined, and then all the position points on the position point structure member can be identified based on subsequent pulse signals. In order to more clearly describe the technical solutions of the present application, several concepts described in this article are specifically explained here.
[0008] The detection area is provided on the position point structure member and can be detected and identified by the position switch. The output when the position switch is within the detection area is different from the output state when it is outside the detection area.
[0009] Position switches usually have two types: normally open and normally closed. Their functions are the same, only the output results are inverted. For the convenience of description, it is agreed in this article that the position switch is in a conducting state when it is within the detection area and in a disconnected state when it is outside the detection area. When the position switch changes from disconnected to conducting, it is a positive edge transition, and when it changes from conducting to disconnected, it is a negative edge transition.
[0010] The position points are located at the starting point and the ending point of the detection area. When the position switch enters the detection area through the starting point of the detection area, a positive edge transition occurs; when the position switch leaves the detection area through the ending point of the detection area, a negative edge transition occurs. In this article, the position points with positive edge transitions are called positive-phase position points, and the position points with negative edge transitions are called negative-phase position points. All positive-phase position points are of the same phase, and all negative-phase position points are also of the same phase. Positive-phase position points and negative-phase position points are mutually inverse-phase position points.
[0011] It is agreed in this article that during the rotation of the camshaft, the position point passed through by the position switch first is in the front, and the position point passed through later is in the back.
[0012] The width of the position point refers to the angular distance between this position point and the adjacent previous position point, that is, the angle that the camshaft needs to rotate from the previous position point to the next position point.
[0013] The calculation formula for the width deviation between two position points is: Delta = ((Amax - Amin) / Amin) * 100%. Where Amax is the larger value of the two widths, and Amin is the smaller value of the two widths.
[0014] To achieve the above object, the technical solution adopted by the present utility model is as follows:
[0015] A single-channel position detection device includes a camshaft, a position switch, and a position point structure member. The position switch is fixedly installed, and the position point structure member is installed on the camshaft and rotates with the camshaft. Only one position switch is included in the position detection device. The position point structure member includes at least two detection areas and at least four position points. One of the position points is a characteristic position point, and the deviation between the width of this position point and the widths of all other in-phase position points is not less than 20%.
[0016] Preferably, the deviation between the width of the characteristic position point and the widths of all other in-phase position points is not less than 50%.
[0017] Preferably, the type of the position switch is one of a groove-shaped photoelectric switch, an inductive proximity switch, or a Hall-type inductive switch.
[0018] Preferably, the characteristic position point is the position point with the largest width among all in-phase position points.
[0019] Preferably, the characteristic position point is the position point with the smallest width among all in-phase position points.
[0020] Compared with the prior art, a single-channel position detection device proposed in this application can determine the absolute position of the current camshaft by the controller identifying the corresponding characteristic position point on the position point structure member. The solution of this application does not need to increase the number of position switches, nor does it need to use a rotary encoder, and can realize the multi-position judgment function based on a single-channel position switch. Thus, it solves the disadvantages of complex structure and high cost of the position detection device in the prior art. Brief Description of the Drawings
[0021] Figure 1 It is a schematic structural diagram of a single-channel position detection device of the present utility model.
[0022] Figure 2 It is a schematic diagram of a 4-position point structure member of Embodiment 1 of a single-channel position detection device of the present utility model.
[0023] Figure 3 It is a schematic diagram of a 6-position point structure member of Embodiment 2 of a single-channel position detection device of the present utility model. Detailed Description of the Embodiment
[0024] Next, in combination with the drawings and the specific implementation manners, a cam structure of a strapping machine core of the present utility model will be further described to facilitate a clearer understanding of the technical idea claimed by the present utility model. Embodiment
[0025] As Figure 1As shown in the figure, an embodiment of the single-channel position detection device of the present application includes a camshaft 11, a position point structure 12, and a position switch 13. The position point structure 12 is installed on the camshaft 11 and rotates together with the camshaft 11. The position switch 13 is fixedly installed.
[0026] In this embodiment, the position switch 13 is a normally open slot-type photoelectric switch. When there is no object blocking it, the switch is in the off state, and when there is an object blocking it, it is in the closed state. In addition to the slot-type photoelectric switch, the position switch 13 here can also be replaced with other types of non-contact position switches (such as inductive proximity switches, Hall-type induction switches, etc.) or contact position switches (such as mechanical limit switches, etc.), as long as the position point structure 12 is adjusted accordingly.
[0027] Non-contact position switches are superior to contact position switches in terms of service life and response speed, but the cost of non-contact position switches is higher than that of contact position switches. Those skilled in the industry can choose a suitable type of position switch according to actual needs.
[0028] Figure 2 This is a schematic diagram of the position point structure 12 in this embodiment. A first detection area 21 and a second detection area 22 are provided on the position point structure 12. The two detection areas contain 4 position points, namely the first position point 211, the second position point 212, the third position point 221, and the fourth position point 222. Among them, the first position point 211 and the third position point 221 are positive-phase position points, and the second position point 212 and the fourth position point 222 are negative-phase position points.
[0029] As shown in the figure, the rotation direction of the position point structure 12 is counterclockwise. Therefore, the width of the first position point 211 is A211, that is, the angle from the position point 222 to the position point 211. Similarly, the width of the second position point 212 is A212, the width of the third position point 221 is A221, and the width of the fourth position point 222 is A222.
[0030] In this embodiment, the width A211 of the first position point is 162°, the width A212 of the second position point is 20°, the width A221 of the third position point is 36°, and the width A222 of the fourth position point is 142°. In this embodiment, the first position point 211 is used as the characteristic position point, and the deviation of the width of this position point from the widths of other in-phase position points exceeds 50%.
[0031] Generally, the rotational speed of the camshaft is determined by the motor that drives its rotation. When the control motor drives the camshaft to rotate at a fixed speed, the widths of the position points on the position point structure can be represented as the time widths and corresponding phases between adjacent signal jumps detected by the position switch on the rotating camshaft. Therefore, the control circuit only needs to sample the time widths and phases of the pulse signals output by the position switch 13 to inversely calculate the widths of the corresponding position points. Therefore, the characteristic position points can be determined by identifying the pulse signals with specific phases and widths.
[0032] In the actual application process, since the rotational speed of the camshaft may fluctuate with the change of the supply voltage, and the change of the resistance at each position during the rotation of the camshaft may also cause measurement deviations. In order to ensure that the characteristic position points can be accurately distinguished, it is necessary to ensure that there is a certain deviation margin between the width of this position point and the widths of other position points with the same phase. The larger this deviation margin is, the easier it is to accurately judge the characteristic position points. Experiments have found that generally, as long as the width deviation between the characteristic position point and the widths of other position points is greater than or equal to 20%, the characteristic position points can be reliably distinguished. Considering the supply voltage fluctuation and the change of the resistance of the camshaft at each position during the working process, it is better to increase a certain margin so that the deviation value is greater than or equal to 50%. Since the position points on the position point structure are determined by the functions that the cam structure needs to achieve, under the condition of permission, increasing the deviation margin as much as possible can make the position identification simpler and more reliable.
[0033] In this embodiment, the first position point 211 is the characteristic position point of the cam, and its position point width A211 is 162°. The width A221 of the third position point with the same phase is 36°, and the deviation between the two is 350%. Embodiment
[0034] The difference between Embodiment 2 and Embodiment 1 is only that the position point structure is different. As Figure 3 shown, there are 3 detection areas provided on the position point structure 12, namely the first detection area 31, the second detection area 32, and the third detection area 33. There are a total of 6 position points, namely the first position point 311, the second position point 312, the third position point 321, the fourth position point 322, the fifth position point 331, and the sixth position point 332. Among them, the first position point 311, the third position point 321, and the fifth position point 331 are positive-phase position points, and the second position point 312, the fourth position point 322, and the sixth position point 332 are negative-phase position points.
[0035] In this embodiment, the width A311 of the first position point is 12°, the width A311 of the second position point is 20°, the width A311 of the third position point is 36°, the width A311 of the fourth position point is 142°, the width A311 of the fifth position point is 120°, and the width A311 of the sixth position point is 30°. Here, the first position point 311 is used as the characteristic position point of the cam, and the in-phase position point closest to it in width is the third position point 321, and the width deviation between the two is 200%.
[0036] As can be seen from the above two embodiments, the channel detection device described in the present application sets corresponding characteristic position points on the position point structure member, so that its width has a certain deviation from the widths of other in-phase position points. In this way, the controller can identify the characteristic position points based on the specific width and phase characteristics in the output signal of the position switch, and then calculate all the position points on the position point structure member. To simplify the discrimination method, the width of the characteristic position point can usually be set as the position point with the minimum width or the maximum width to facilitate the controller to make a judgment. In the present application, in Embodiment 1, the characteristic position point is set as the position point with the maximum width, and in Embodiment 2, the characteristic position point is set as the position point with the minimum width.
[0037] For those skilled in the art, various corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the protection scope of the claims of the present utility model.
Claims
1. A single-channel position detection device, characterized in that: include: Camshafts, position switches, position point structural parts; The position switch is fixedly installed, and the position point structure is installed on the camshaft and rotates with the camshaft; The position detection device only includes one position switch; The position point structure comprises at least 2 detection areas and at least 4 position points; The position points include a characteristic position point, and the deviation between the width of the characteristic position point and the width of all other in-phase position points is not less than 20%.
2. A single-channel position detection device according to claim 1, characterized in that: The deviation between the width of the characteristic position point and the width of all other in-phase position points is not less than 50%.
3. A single-channel position detection device according to claim 2, characterized in that: The position switch is a type of a slot-shaped photoelectric switch, an inductive proximity switch or a Hall-type inductive switch.
4. A single-channel position detection device according to claim 3, characterized in that: The characteristic position point is the position point with the largest width among all the in-phase position points.
5. A single-channel position detection device according to claim 3, characterized in that: The characteristic position point is the position point with the smallest width among all the in-phase position points.