Crankshaft sensor circuit and crankshaft sensor

Abstract

A crankshaft sensor circuit, comprising: a magnetoelectric induction circuit (21), configured to detect a target signal tooth on a crankshaft signal plate, and output a corresponding pulse signal by means of a signal output end when the target signal tooth is detected; and a standardization processing circuit (22), configured to process the pulse signal into a standardized pulse signal, the pulse width of the standardized pulse signal being a preset standard width. In this way, when being applicable to different crankshaft signal plates, the crankshaft sensor is not affected by the production consistency problem of the crankshaft signal plates, so that the detection accuracy is improved. In addition, also provided is a crankshaft sensor.

Description

Crankshaft sensor circuit and crankshaft sensor Cross-reference to Related Applications

[0001] This application claims priority to Chinese Patent Application No. 202410834320.0, filed on June 26, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application belongs to the technical field of sensors, and particularly relates to a crankshaft sensor circuit and a crankshaft sensor. BACKGROUND

[0003] The crankshaft sensor is used to detect a crankshaft speed signal, so that a controller can perform engine control according to the signal provided by the crankshaft sensor. The performance of the crankshaft sensor is determined by the circuit design of the crankshaft sensor. At present, when the crankshaft sensor detects the speed signal of a crankshaft signal disc of different vehicle models, the consistency of the crankshaft signal disc in production causes differences in the signal output by the crankshaft sensor circuit, which further leads to poor detection accuracy. SUMMARY

[0004] The technical solution of the present application provides a crankshaft sensor circuit and a crankshaft sensor, which can at least to some extent make the crankshaft sensor suitable for different crankshaft signal discs without being affected by the production consistency of the crankshaft signal disc, thereby improving the detection accuracy.

[0005] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0006] According to a first aspect of the technical solution of the present application, a crankshaft sensor circuit is provided, comprising:

[0007] A magneto-inductive sensing circuit is configured to detect a target signal tooth on a crankshaft signal disc and output a corresponding pulse signal through a signal output end when the target signal tooth is detected.

[0008] A standardization processing circuit is connected to the signal output end of the magneto-inductive sensing circuit. The standardization processing circuit is configured to process the pulse signal into a standardized pulse signal, and the pulse width of the standardized pulse signal is a preset standard width.

[0009] In some technical solutions of the present application, based on the foregoing solution, the magneto-inductive sensing circuit comprises at least one magnetic induction resistor, and the film layer structure of each magnetic induction resistor comprises:

[0010] A free magnetic layer;

[0011] Reference magnetic layer;

[0012] An insulating barrier layer is arranged between the free magnetic layer and the reference magnetic layer;

[0013] An intermediate layer is arranged on a side of the reference magnetic layer away from the insulating barrier layer, the intermediate layer comprises a stabilizing layer arranged close to the reference magnetic layer, wherein the reference magnetic layer comprises N kinds of elements, one of which is a diffusible element, and the stabilizing layer comprises M kinds of elements, one of which is the diffusible element, and N and M are integers greater than 1.

[0014] In some embodiments of the present application, based on the foregoing scheme, the ratio between the thickness of the reference magnetic layer and the thickness of the free magnetic layer ranges from 1.2 to 2.5.

[0015] In some embodiments of the present application, based on the foregoing scheme, the free magnetic layer and the reference magnetic layer are composed of CoxFeyRez, wherein Re is the diffusible element, and Re includes at least one of aluminum (Al), boron (B), selenium (Si), and manganese (Mn), and x, y, and z represent the proportions of Co, Fe, and Re, respectively.

[0016] In some embodiments of the present application, based on the foregoing scheme, the thickness of the insulating barrier layer ranges from 0.8 to 3 nm.

[0017] In some embodiments of the present application, based on the foregoing scheme, the stabilizing layer is composed of the Re element.

[0018] In some embodiments of the present application, based on the foregoing scheme, the rising edge time of the magneto-electric sensing circuit ranges from 0.4 to 2.6 μs, and the falling edge time of the magneto-electric sensing circuit ranges from 0.2 to 1.2 μs.

[0019] In some embodiments of the present application, based on the foregoing scheme, the standardization processing circuit comprises:

[0020] A monostable multivibrator is connected to the signal output end of the magneto-electric sensing circuit, and the monostable multivibrator is configured to process the pulse signal into a standardized square wave signal, and the pulse width of the standardized square wave signal is the preset standard width.

[0021] In some embodiments of the present application, based on the foregoing scheme, the monostable multivibrator comprises a set end, a division instruction end, and a first power input end, and the crankshaft sensor circuit further comprises:

[0022] a power supply;

[0023] a voltage stabilizing circuit, the voltage stabilizing circuit comprising a second power supply input end and a power supply output end, the second power supply input end being connected with the power supply, and the power supply output end being connected with the first power supply input end;

[0024] a power supply stabilizing circuit, the power supply stabilizing circuit comprising a first resistor, a second resistor and a third resistor, a first end of the first resistor being connected with the power supply output end and the first power supply input end respectively, a second end of the first resistor being connected with a first end of the second resistor and the division instruction end respectively, a second end of the second resistor being connected with a first end of the third resistor and a ground end respectively, and a second end of the third resistor being connected with the setting end.

[0025] In some technical solutions of the present application, based on the foregoing solutions, further comprising:

[0026] a filter circuit, the filter circuit comprising a first capacitor, a second capacitor and a fourth resistor, a first end of the first capacitor being connected with the second power supply input end and a first end of the fourth resistor respectively, a second end of the first capacitor being grounded, a second end of the fourth resistor being connected with the power supply, a first end of the second capacitor being connected with the first power supply input end, and a second end of the second capacitor being grounded.

[0027] According to a second aspect of the technical solutions of the present application, a crankshaft sensor is provided, comprising the crankshaft sensor circuit according to any one of the first aspect.

[0028] In some technical solutions of the present application, based on the foregoing solutions, a sensor housing is comprised, a sensor chip comprising a magneto-electric sensing circuit is arranged in the sensor housing, and the sensor chip is arranged on the bottom of the sensor housing.

[0029] In some technical solutions of the present application, based on the foregoing solutions, the bottom of the sensor housing is provided with a receiving cavity, and the sensor chip is embedded in the receiving cavity.

[0030] In some technical solutions of the present application, based on the foregoing solutions, further comprising a magnet piece, the magnet piece being arranged on a side of the sensor chip away from the bottom of the sensor housing, and the magnet piece having a corresponding relationship between a magnetic field strength and a sensitivity parameter of the sensor chip.

[0031] In some technical solutions of the present application, based on the foregoing solutions, the sensitivity parameter comprises a signal along time and / or a magnetic resistance change rate, the signal along time being positively correlated with the magnetic field strength, and the magnetic resistance change rate being negatively correlated with the magnetic field strength.

[0032] In some technical solutions of the present application, based on the foregoing scheme, the magnet piece adopts a samarium-cobalt magnet, and the magnetic field strength of the ferromagnetic piece ranges from 200 to 355 mT.

[0033] One or more technical solutions provided by the technical solutions of the present application at least achieve the following technical effects or advantages:

[0034] The present application detects the target signal tooth on the crankshaft signal disc through a magneto-electric induction circuit, and outputs a corresponding pulse signal through a signal output end when the target signal tooth is detected; the pulse signal is processed into a standardized pulse signal through a standardization processing circuit, the pulse width of the standardized pulse signal is a preset standard width, and then the rotational speed signal of the crankshaft sensor can be determined according to a plurality of pulse signals with the preset standard width, thereby overcoming the influence of the production consistency of the crankshaft signal disc on the detection accuracy, and improving the signal detection accuracy.

[0035] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0036] The drawings incorporated into the specification and forming a part of the specification, show the technical solutions consistent with the present application, and together with the specification, serve to explain the principles of the present application. Obviously, the drawings in the following description are only some technical solutions of the present application, and other drawings can be obtained by those skilled in the art without creative labor. In the drawings:

[0037] Fig. 1 shows a circuit schematic diagram of a crankshaft sensor of the technical solutions of the present application;

[0038] Fig. 2 shows a structure diagram of a magnetic tunnel junction of the technical solutions of the present application;

[0039] Fig. 3 shows another structure diagram of a magnetic tunnel junction of the technical solutions of the present application;

[0040] Fig. 4 shows a perspective structure diagram of a crankshaft sensor of the technical solutions of the present application;

[0041] Fig. 5 shows an exploded view of a crankshaft sensor of the technical solutions of the present application;

[0042] Fig. 6 shows a partial enlarged view of A in Fig. 5.

[0043] Explanation of reference signs:

[0044] 21 - magnetoelectric induction circuit; 22 - standardization processing circuit; 23 - voltage stabilization circuit; 24 - power supply stabilization circuit; 25 - filter circuit; 1 - free magnetic layer; 2 - reference magnetic layer; 3 - insulating barrier layer; 4 - intermediate layer; 41 - stabilization layer; 42 - coupling layer; 5 - pinning layer; 6 - anti-ferromagnetic layer; 7 - first separation layer; 8 - second separation layer; 9 - conductive layer; 10 - buffer layer; 11 - base layer; 12 - sensor housing; 13 - sensor chip; 14 - accommodating cavity; 15 - magnet piece. DETAILED DESCRIPTION

[0045] The technical solutions in the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described technical solutions are only a part of the technical solutions in the present application, rather than all the technical solutions. Based on the technical solutions in the present application, all other technical solutions obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0046] In addition, the described features, structures or characteristics can be combined in any suitable manner in one or more technical solutions. In the following description, many specific details are provided to give a full understanding of the technical solutions of the present application. However, those skilled in the art will realize that the technical solutions of the present application can be practiced without one or more of the specific details, or can employ other methods, components, devices, steps, etc. In other cases, well-known methods, devices, implementations or operations are not shown or described in detail to avoid obscuring the aspects of the present application.

[0047] The block diagrams shown in the accompanying drawings are only functional entities, which do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0048] The flowcharts shown in the accompanying drawings are only exemplary illustrations, which do not necessarily include all contents and operations / steps, and are not necessarily executed in the described order. For example, some operations / steps can be further decomposed, and some operations / steps can be combined or partially combined, so that the actual execution order can be changed according to the actual situation.

[0049] It should also be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described accompanying drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the objects thus used can be interchanged under appropriate circumstances, so that the technical solutions of the present application described herein can be implemented in an order other than that illustrated or described.

[0050] Fig. 1 shows a circuit schematic of a crankshaft sensor according to the present application.

[0051] According to a first aspect of the present application, a crankshaft sensor circuit is provided, comprising:

[0052] A magneto-inductive sensing circuit 21 configured to detect a target signal tooth on a crankshaft signal disc and output a corresponding pulse signal through a signal output end when the target signal tooth is detected;

[0053] A standardization processing circuit 22 connected to the signal output end of the magneto-inductive sensing circuit 21, the standardization processing circuit 22 being configured to process the pulse signal into a standardized pulse signal, the pulse width of the standardized pulse signal being a preset standard width.

[0054] It can be understood that the crankshaft signal disc usually includes one missing tooth and a plurality of signal teeth arranged at equal intervals. The detection principle of the crankshaft sensor for the signal disc rotation speed signal is as follows: after detecting the missing tooth, one of the signal edges (rising edge or falling edge) is taken as the detection starting point, and once the signal edge is detected, a pulse signal is sent out, and when the next signal edge is detected, a pulse signal is sent out again. Since the missing teeth are arranged at equal intervals in an ideal state, the number of detected pulse signals can be used to determine the rotation speed of the crankshaft. However, due to the production accuracy of the crankshaft signal disc, the missing teeth may not be completely consistent and arranged at equal intervals, so the pulse signal width sent out by the sensor between two signal edges may not be completely consistent. In addition, if the rotation speed of the signal disc is different, it may also cause the pulse width of the pulse signal output by the sensor to change in the range of 1 RPM~10000 RPM.

[0055] Based on this, the present application processes the pulse signal into a standardized pulse signal through the standardization processing circuit 22, the pulse width of the standardized pulse signal being a preset standard width, so that the rotation speed signal of the crankshaft sensor can be determined according to a plurality of pulse signals with the preset standard width, overcoming the production consistency problem of the crankshaft signal disc and the influence of the rotation speed signal change on the detection accuracy, and improving the signal detection accuracy.

[0056] In some technical solutions, the magneto-inductive sensing circuit 21 is packaged in a magnetic sensitive chip, for example, a magnetic sensitive chip with model number SD208, which has a voltage stabilizer integrated inside and can withstand an external power voltage fluctuation of 4.5 V~24V.

[0057] In some technical solutions, the standardization processing circuit 22 includes:

[0058] A monostable multivibrator is connected with the signal output end of the magneto-inductive induction circuit 21, and is configured to process the pulse signal into a standardized square wave signal with a pulse width of the preset standard width.

[0059] For example, the monostable multivibrator can be a 555 timer, such as a timer of model NE555 or LM555, or a monostable trigger, such as a monostable trigger of CD4098B.

[0060] It can be understood that the monostable multivibrator is used to process the signal generated by the SD208 magnetic sensor chip detection signal disc. Due to the consistency problem of the signal disc and the difference in the rotating speed of the signal disc, the negative pulse width of the output signal of the magnetic sensor chip is inconsistent, for example, in the range of 1 RPM~10000 RPM, the corresponding output frequency is 10HZ~10KHZ, and the negative pulse width is between 50mS~50uS. In order to standardize the output signal, the negative pulse width under different rotating speeds can be adjusted to about 45uS after being processed by the monostable multivibrator, so as to overcome the influence of the above problems on the detection accuracy.

[0061] In some technical solutions, the monostable multivibrator includes a set end, a division instruction end and a first power input end, and the crankshaft sensor circuit further includes:

[0062] a power supply;

[0063] a voltage stabilizing circuit 23 including a second power input end and a power output end, the second power input end being connected with the power supply, and the power output end being connected with the first power input end;

[0064] a power supply stabilizing circuit 24 including a first resistor, a second resistor and a third resistor, a first end of the first resistor being connected with the power output end and the first power input end respectively, a second end of the first resistor being connected with a first end of the second resistor and the division instruction end respectively, a second end of the second resistor being connected with a first end of the third resistor and a ground end respectively, and a second end of the third resistor being connected with the set end.

[0065] It should be noted that the fluctuation of external voltage may interfere with the performance of the monostable multivibrator U3, therefore, the voltage stabilizing chip U2 is used to provide stable voltage supply for the monostable multivibrator, so as to ensure the normal work of the monostable multivibrator U3, wherein the highest working voltage of the voltage stabilizing chip U2 can be 50V.

[0066] Wherein, the first resistance, the second resistance and the third resistance are R3, R4 and R5 respectively, and are the peripheral resistance required for the operation of the monostable multivibrator. In order to ensure that the resistance can meet the current and power requirements, thereby ensuring the stability and reliability of the chip power supply, the current borne by R3, R4 and R5 is relatively small, and we use a resistance with an accuracy of ±1% and a power of 62.5mW. The specific resistance value allocation is as follows: R3 is 102K, R4 is 976K, and R5 is 280K.

[0067] In some technical solutions, further comprising:

[0068] The filter circuit 25 comprises a first capacitor, a second capacitor and a fourth resistance, the first end of the first capacitor is connected with the second power input end and the first end of the fourth resistance respectively, the second end of the first capacitor is grounded, the second end of the fourth resistance is connected with the power supply, the first end of the second capacitor is connected with the first power input end, and the second end of the second capacitor is grounded.

[0069] In some technical solutions, when the magnetic sensitive chip adopts a drain open circuit output stage structure, the chip output end is further connected with a pull-up resistance.

[0070] It can be understood that, in the application environment with a large amount of stray noise, in order to ensure stability, a basic RC low-pass filter composed of a fourth resistance R1 and a first capacitor C1 is additionally arranged on the power supply line, and a second capacitor C3 is further arranged to filter the voltage after voltage stabilization.

[0071] In order to ensure that the resistance can meet the current and power requirements, thereby ensuring the stability and reliability of the chip power supply, R1 is selected as a thick film resistance, the accuracy of which reaches ±1%, and the power is 125mW. The current borne by the pull-up resistance R2 is relatively small, and a resistance with an accuracy of ±1%, a power of 62.5mW and a resistance value of 10K is used. The main function of C1 is to absorb power supply noise, and the capacitance value can be 100nF, and the accuracy is controlled within ±10%. C3 is used to filter the voltage after voltage stabilization, and the capacitance value is 100nF, and the accuracy is also controlled within ±10%.

[0072] In order to improve the detection accuracy of the crankshaft sensor, the magnetic induction circuit in the technical solution of the application comprises at least one magnetic induction resistance, for example: the magnetic induction circuit adopts a push-pull type Wheatstone bridge structure, that is, the push-pull type Wheatstone bridge structure comprises four resistances, each resistance is a magnetic tunnel junction, which is also called a magnetic induction resistance for ease of understanding. The film layer structure of each magnetic induction resistance is described below.

[0073] In order to facilitate understanding of the technical solution of the application, first, the concept of magnetic tunnel junction involved in the technical solution of the application is described.

[0074] Magnetic Tunnel Junction (MTJ): is an important component to realize various sensors, for example, is an important component of crankshaft sensor. Mainly includes free magnetic layer / insulating barrier layer / ferromagnetic layer, wherein the free magnetic layer and the reference magnetic layer are usually composed of ferromagnetic material, the reference magnetic layer has a fixed magnetization direction, the magnetization direction of the free magnetic layer can be reversed, and the magnetization direction of the free magnetic layer is different from or the same as the magnetization direction of the reference magnetic layer. The resistance of the corresponding insulating barrier layer is different. Specifically, when the magnetization direction of the free magnetic layer is the same (parallel) as the magnetization direction of the reference magnetic layer, the insulating barrier layer presents a low resistance state, and when the magnetization direction of the free magnetic layer is opposite (antiparallel) to the magnetization direction of the reference magnetic layer, the insulating barrier layer presents a high resistance state.

[0075] Figure 2 shows a structure diagram of the magnetic tunnel junction of the technical scheme of the present application; and Figure 3 shows another structure diagram of the magnetic tunnel junction of the technical scheme of the present application.

[0076] In some technical schemes, the film layer structure of each magnetic induction resistance includes:

[0077] a free magnetic layer 1;

[0078] a reference magnetic layer 2;

[0079] an insulating barrier layer 3, which is arranged between the free magnetic layer 1 and the reference magnetic layer 2;

[0080] an intermediate layer 4, which is arranged on the side of the reference magnetic layer 2 away from the insulating barrier layer 3, and the intermediate layer 4 includes a stabilizing layer 41 arranged close to the reference magnetic layer 2, wherein the composition material of the reference magnetic layer 2 includes N kinds of elements, one of which is a diffusible element, and the composition material of the stabilizing layer 41 includes M kinds of elements, one of which is the diffusible element, and N and M are both integers greater than 1.

[0081] It can be understood that the detection sensitivity is the performance factor that the magnetic tunnel junction gives priority to, therefore, the free magnetic layer 1 and the reference magnetic layer 2 of the magnetic tunnel junction usually adopt ferromagnetic materials that can improve the magnetic resistance change rate (i.e. improve the detection sensitivity), but these ferromagnetic materials may include non-stable elements, such as aluminum elements, etc. The non-stable elements may diffuse to the insulating barrier layer 3 under the influence of environmental temperature, etc., thereby affecting the performance of the insulating barrier layer 3, further affecting the magnetic resistance change rate, and finally leading to the decrease of the detection sensitivity of the magnetic tunnel junction.

[0082] Based on the above, the application sets the intermediate layer 4 on the side of the reference magnetic layer 2 of the magnetic tunnel junction away from the insulating barrier layer 3, and sets the stable layer 41 of the intermediate layer 4 close to the reference magnetic layer 2. Since the composition material of the stable layer 41 has the same non-stable element as the composition material of the reference magnetic layer 2, when the non-stable element of the reference magnetic layer 2 diffuses due to the influence of temperature and the like, the stable layer 41 can absorb and inhibit the non-stable element in the reference magnetic layer 2, thereby preventing the non-stable element from diffusing upward to the insulating barrier layer 3, thereby affecting the performance of the insulating barrier layer 3, and further affecting the magnetic resistance change rate, thereby affecting the overall performance of the magnetic tunnel junction.

[0083] In some embodiments, the composition material of the free magnetic layer 1 and the reference magnetic layer 2 is CoxFeyRez, wherein Re element is the non-stable element, the Re element includes at least one of aluminum (Al), boron (B), selenium (Si) and manganese (Mn), and x, y and z respectively represent the proportions of Co element, Fe element and Re element.

[0084] In some embodiments, in the composition material CoxFeyRez of the free magnetic layer 1, the proportions of Co element, Fe element and Re element are x1:y1:z1, wherein x1+y1+z1=100, the value range of x1 is 40-80, the value range of y1 is 10-40, and the value range of z1 is 10-30.

[0085] In some embodiments, in the composition material CoxFeyRez of the reference magnetic layer 2, the proportions of Co element, Fe element and Re element are x2:y2:z2, wherein x2+y2+z2=100, the value range of x2 is 20-60, the value range of y2 is 20-60, and the value range of z2 is 10-30.

[0086] In some embodiments, the thickness of the reference magnetic layer 2 is greater than the thickness of the free magnetic layer 1.

[0087] It can be understood that when the thickness of the reference magnetic layer 2 is greater than the thickness of the free magnetic layer 1, and the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1 have a proper ratio relationship, the reference magnetic layer 2 itself can realize the fixation of the magnetization direction, and is not affected by the free magnetic layer 1. For example, when the ratio between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1 is in the range of 1.2-2.5, the reference magnetic layer 2 itself can realize the fixation of the magnetization direction, and is not affected by the free magnetic layer 1.

[0088] In some embodiments, the ratio between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1 is in the range of 1.2-2.5.

[0089] It can be understood that when the thickness of the reference magnetic layer 2 is greater than the thickness of the free magnetic layer 1, and there is a proper ratio between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1, the reference magnetic layer 2 itself can realize the fixation of the magnetization direction, and is not affected by the free magnetic layer 1. For example, when the ratio between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1 ranges from 1.2 to 2.5, the reference magnetic layer 2 itself can realize the fixation of the magnetization direction, and is not affected by the free magnetic layer 1.

[0090] In some embodiments, the composition of the stabilizing layer 41 includes the Re element, i.e., at least one of aluminum (Al), boron (B), selenium (Si), and manganese (Mn), which is adapted to the Re element in the reference magnetic layer 2, so as to absorb and inhibit the Re element in the reference magnetic layer 2 when the Re element in the reference magnetic layer 2 diffuses, and prevent the Re element in the reference magnetic layer 2 from diffusing to the insulating barrier layer 3 and affecting the performance of the insulating barrier layer 3.

[0091] In some embodiments, the content of the Re element in the stabilizing layer 41 in the M elements ranges from 5% to 20%.

[0092] It can be understood that the specific content of the Re element in the stabilizing layer 41 in the M elements can be determined according to the content of the Re element in the reference magnetic layer 2 in the N elements. The absorption capacity of the Re element in the stabilizing layer 41 for the Re element in the reference magnetic layer 2 should have an absorption threshold. When the absorption threshold is reached, the Re element in the stabilizing layer 41 and the Re element in the reference magnetic layer 2 can reach a dynamic balance, so as to prevent the Re element in the reference magnetic layer 2 from diffusing upward to the insulating barrier layer 3 on the one hand, and ensure that the diffusion amplitude of the Re element in the reference magnetic layer 2 is small and does not affect the performance of the reference magnetic layer 2 itself on the other hand.

[0093] In some embodiments, when the composition of the reference magnetic layer 2 is CoxFeyAlz, the composition of the stabilizing layer 41 is an aluminum-magnesium alloy material, which is used to absorb and inhibit the diffusion of Al in CoxFeyAlz and improve the temperature stability of the magnetoresistance change rate. For example, the thickness of the aluminum-magnesium alloy material is not higher than 0.5 nm.

[0094] It can be understood that when the thickness of the reference magnetic layer 2 is greater than the thickness of the free magnetic layer 1, and there is a proper ratio relationship between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1, the reference magnetic layer 2 can realize the fixation of the magnetization direction by itself, and is not affected by the free magnetic layer 1. For example, when the ratio between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1 ranges from 1.2 to 2.5, the reference magnetic layer 2 can realize the fixation of the magnetization direction by itself, and is not affected by the free magnetic layer 1. At this time, it is not necessary to further set the film layer structure of the pinning layer 5 and the anti-ferromagnetic layer 6 to fix the magnetization direction of the reference magnetic layer 2.

[0095] When the thickness of the reference magnetic layer 2 is greater than the thickness of the free magnetic layer 1, but the difference between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1 is small, for example, the thickness of the free magnetic layer 1 ranges from 0.8 nm to 6 nm, and the thickness of the reference magnetic layer 2 ranges from 2 nm to 8 nm, the reference magnetic layer 2 cannot realize the fixation of the magnetization direction by itself, and is affected by the free magnetic layer 1. Therefore, it is still necessary to further set the film layer structure of the pinning layer 5 and the anti-ferromagnetic layer 6 to fix the magnetization direction of the reference magnetic layer 2.

[0096] In some technical solutions, further comprising:

[0097] The pinning layer 5 is arranged on the side of the intermediate layer 4 away from the reference magnetic layer 2, and the composition material of the pinning layer 5 includes at least one of cobalt-iron-boron (CoFeB), cobalt-iron (CoFe), nickel-iron (NiFe), iron-gallium-boron (FeGaB), cobalt (Co), iron (Fe), nickel-iron-cobalt (NiFeCo) and cobalt-niobium-zirconium (CoNbZr), for example, Cox3Fey3 is adopted, wherein x3+y3=100, and the value range of x3 is 40-80.

[0098] The anti-ferromagnetic layer 6 is arranged on the side of the pinning layer 5 away from the intermediate layer 4, and the composition material of the anti-ferromagnetic layer 6 includes at least one of platinum-manganese alloy (PtMn), iridium-manganese alloy (IrMn) and iron-manganese alloy (FeMn).

[0099] In some technical solutions, the thickness of the pinning layer 5 ranges from 2 nm to 5 nm.

[0100] In some technical solutions, the thickness of the anti-ferromagnetic layer 6 ranges from 5 nm to 20 nm.

[0101] In some technical solutions, the intermediate layer 4 further includes:

[0102] The coupling layer 42 is arranged between the stabilizing layer 41 and the pinning layer 5, and the composition material of the coupling layer 42 includes at least one of ruthenium (Ru) and tantalum (Ta).

[0103] Specifically, the coupling layer 42 can isolate the reference magnetic layer 2 and the pinning layer 5 while enabling the reference magnetic layer 2 and the pinning layer 5 to be antiferromagnetic exchange coupled. For example, the coupling layer 42 is a ruthenium layer. Since ruthenium has antiferromagnetic properties, the magnetic field generated by the current passing through the ruthenium layer magnetizes the pinning layer 5, and then the reference magnetic layer 2 and the pinning layer 5 are opposite in direction, repel each other, and are locked to each other, thereby realizing the stability of the magnetic field of the reference magnetic layer 2.

[0104] In some embodiments, the thickness of the insulating barrier layer 3 is 0.8-3 nm, and the insulating barrier layer 3 is composed of at least one of magnesium borate (Mg3B2O6), aluminum trioxide (Al2O3), and magnesium oxide (MgO).

[0105] In some embodiments, the device further comprises:

[0106] The first isolation layer 7 is disposed on the side of the free magnetic layer 1 away from the insulating barrier layer 3, and the first isolation layer 7 is composed of at least one of tantalum (Ta) and ruthenium (Ru).

[0107] The second isolation layer 8 is disposed on the side of the first isolation layer 7 away from the free magnetic layer 1, and the second isolation layer 8 is composed of magnesium (Mg).

[0108] The conductive layer 9 is disposed on the side of the second isolation layer 8 away from the first isolation layer 7, and the conductive layer 9 is composed of at least one of platinum (Pt), gold (Au), tungsten (W), aluminum (Al), copper (Cu), silver (Ag), ruthenium (Ru), tantalum (Ta), and titanium (Ti).

[0109] The buffer layer 10 is disposed on the side of the intermediate layer 4 away from the reference magnetic layer 2, and the buffer layer 10 is composed of at least one of platinum (Pt), gold (Au), tungsten (W), aluminum (Al), copper (Cu), and titanium (Ti).

[0110] It should be noted that the first isolation layer 7 has good oxidation resistance and good compactness, can prevent the nano-multilayer film structure from being contaminated during the deposition of the thin film, and thus avoids affecting the performance of the device. The thickness of the first isolation layer 7 is 2-10 nm.

[0111] It should be noted that the second isolation layer 8 is used to stabilize the structure of the free magnetic layer 1 during the annealing process of the magnetic tunnel junction preparation process, and to reduce the temperature fluctuation of the magnetoresistance change rate of the magnetic tunnel junction at different temperatures. The thickness of the second isolation layer 8 is 0.5-1 nm.

[0112] It should be noted that the conductive layer 9 can be the metal material described above, can also be a topological insulator, and can also be other conductor materials.

[0113] It should be noted that the buffer layer 10 is a transition from the insulating substrate to the functional magnetic tunnel structure, and also serves as the bottom electrode of the functional magnetic tunnel structure. The thickness of the buffer layer 10 is in the range of 5nm to 15nm. When the thickness of the reference magnetic layer 2 is greater than the thickness of the free magnetic layer 1, and there is a proper ratio relationship between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1, and the reference magnetic layer 2 itself can realize the fixation of the magnetization direction, the buffer layer 10 is arranged on the side of the intermediate layer 4 away from the reference magnetic layer 2. When the thickness of the reference magnetic layer 2 is greater than the thickness of the free magnetic layer 1, but the difference between the thickness of the reference magnetic layer 2 and the thickness of the free magnetic layer 1 is small, and it is necessary to further arrange the film layer structure of the pinning layer 5 and the antiferromagnetic layer 6 to fix the magnetization direction of the reference magnetic layer 2, the buffer layer 10 is arranged on the side of the antiferromagnetic layer 6 away from the pinning layer 5.

[0114] It can be understood that the magnetic tunnel junction also includes a substrate layer 11, which can be a semiconductor substrate, a bare chip (a chip that has not been packaged), or other substrate structures, which are not limited by the technical solutions of the present application. The composition material of the substrate layer 11 can be at least one of SiO2, MgO, Al2O3, Si, SiN, SiC, GaAs (gallium arsenide), InP (indium phosphide), SrTiO3 (strontium titanate), LaAlO3 (lanthanum aluminate crystal), and SrRuO3 (strontium ruthenate).

[0115] In some technical solutions, the rising edge time range of the magneto-electric sensing circuit 21 is 0.4μs~2.6μs, and the falling edge time range of the magneto-electric sensing circuit 21 is 0.2μs~1.2μs.

[0116] It should be noted that since the crankshaft sensor adopts the magnetic tunnel junction of any one of the first aspect, the film layer structure adopted by the magnetic tunnel junction has good detection sensitivity, and thus the rising edge time range of the crankshaft sensor reaches 0.4μs~2.6μs, and the falling edge time range of the crankshaft sensor reaches 0.2μs~1.2μs, so the detection sensitivity of the crankshaft sensor to the position change of the signal disc is greatly improved.

[0117] In order to facilitate understanding of the technical solutions of the present application, first, the concept of the crankshaft sensor involved in the technical solutions of the present application is described.

[0118] Crankshaft sensor, also known as engine speed and crankshaft speed sensor, etc., its role is to collect crankshaft rotation angle and engine speed signal, and input to the controller, in order to determine the injection sequence, injection timing, ignition sequence and ignition timing, then according to the signal monitoring the size of the crankshaft angle fluctuation to determine whether the engine has misfire phenomenon. Crankshaft position sensor is generally installed on the crankshaft front end and near the flywheel variable speed shell position.

[0119] At present, in the related art, the crankshaft sensor mainly adopts differential Hall sensor, the signal output by the Hall effect of the Hall sensor itself will be affected by temperature, so there is a certain temperature drift phenomenon; in addition, the Hall sensor needs to use magnetic ring structure to amplify the magnetic field, so as to improve the sensitivity of the Hall signal output, but this way will lead to the power consumption of the Hall effect is large; in addition, the output signal of the Hall sensor is easy to be disturbed by the external magnetic field, thereby affecting the measurement accuracy; furthermore, due to the poor sensitivity of the Hall sensor, the air gap between the sensor head detection chip and the crankshaft signal disc (i.e. the distance between the sensor chip and the signal disc) needs to be closer, because the sensor chip realizes signal detection by sensing the size of the magnetic field around the signal disc cutting sensor, the larger the air gap between the sensor head detection chip and the crankshaft signal disc, the weaker the influence of the rotation of the signal disc on the magnetic field around the sensor; furthermore, the Hall sensor requires higher magnetic field strength, and the sensor chip needs to be closely assembled with the magnet, when the magnet is in a high temperature environment for a long time, the magnetic material will decay, the magnetic field strength of the magnet will weaken, which will cause the output signal of the sensor to weaken, and even cause the signal to be lost.

[0120] As known from the above, the existing crankshaft sensor at least has the problem of poor detection sensitivity, based on this, the second aspect of the present application provides a crankshaft sensor, which comprises the crankshaft sensor circuit of any one of the first aspect.

[0121] FIG. 4 shows a perspective view of the crankshaft sensor of the present application; FIG. 5 shows an exploded view of the crankshaft sensor of the present application; and FIG. 6 shows a partial enlarged view of A in FIG. 5.

[0122] In some technical solutions, a sensor shell 12 is provided, and a sensor chip 13 comprising a magneto-electric induction circuit is arranged in the sensor shell 12.

[0123] In some technical solutions, the bottom of the sensor shell 12 is provided with a receiving cavity 14, and the sensor chip 13 is embedded in the receiving cavity 14.

[0124] For example, the bottom of the sensor shell 12 is provided with a receiving cavity 14, and the sensor chip 13 is embedded in the receiving cavity 14.

[0125] It can be understood that the accommodating cavity 14 is integrally formed with the sensor shell 12, and the sensor chip 13 is embedded in the accommodating cavity 14 to be fixed, so that the sensor chip 13 is as close to the shell edge as possible, and then the magnetic induction unit in the sensor chip 13 is as close to the signal disc as possible, the air gap between the sensor chip 13 and the signal disc is reduced, and then the sensor chip 13 is more sensitive to the induction of the signal disc cutting magnetic field, so that the output signal obtained by measurement is more stable and reliable.

[0126] In some technical solutions, the magnet piece 15 is arranged on the side of the bottom of the sensor chip 13 away from the sensor shell 12, and the magnetic field strength of the magnet piece 15 has a corresponding relationship with the sensitivity parameter of the sensor chip 13.

[0127] It can be understood that the magnet piece 15 is arranged opposite to the sensor chip 13, so that the sensor chip 13 and the magnet piece 15 are on the same central axis, that is, they are in a symmetrical magnetic field, thereby improving the induction capacity of the signal disc cutting magnetic field change. It should be noted that the sensor chip 13 and the magnet piece 15 of the technical solution of the present application do not need to be closely assembled, so that the magnetic material attenuation of the magnet piece 15 can be slowed down to a certain extent, and the service life of the magnet piece 15 is improved.

[0128] In some technical solutions, the sensitivity parameter includes signal along time and / or magnetoresistance change rate, the signal along time is positively correlated with the magnetic field strength, and the magnetoresistance change rate is negatively correlated with the magnetic field strength.

[0129] It can be understood that in the case that the signal along time and / or the magnetoresistance change rate of the sensor chip 13 is determined, the magnetic field strength of the ferromagnetic piece is too high or too low, which is not conducive to ensuring the detection accuracy of the sensor chip 13. Therefore, by establishing the corresponding relationship between the signal along time and / or the magnetoresistance change rate and the magnetic field strength of the magnet piece 15, the magnet piece 15 with a corresponding magnetic field strength can be configured according to the sensitivity parameter of the sensor chip 13, so as to ensure the detection accuracy of the sensor chip 13.

[0130] In some technical solutions, the magnet piece 15 adopts a samarium-cobalt magnet, and the magnetic field strength of the ferromagnetic piece ranges from 200 mT to 355 mT.

[0131] It should be noted that the samarium-cobalt magnet has a high demagnetization temperature, so that the magnetic field strength of the sensor in a high-temperature use environment can be prevented from changing, the magnetic material attenuation of the magnet piece 15 is further slowed down, and the service life of the magnet piece 15 is improved.

[0132] In some technical solutions, the sensor housing 12 is provided with a circuit board, and the circuit board is a flexible circuit board, such as a FPC flexible circuit board with a polyimide film as a substrate, so as to improve the anti-vibration capability of the module.

[0133] It should be noted that the flexible circuit board is provided with the sensor chip 13, the pins of the sensor chip 13 are welded on the flexible circuit board, the other end of the flexible circuit board is welded on the pin metal terminal, the metal terminal also extends out of the housing to realize signal connection, and it can be understood that the sensor chip 13 is provided with three pin metal terminal output ports, which correspond to the power supply end VDD, the output end OUT and the ground end GND of the cam phase sensor respectively.

[0134] It can be understood that the pin metal terminal can be used as an insert to be injection molded together with the sensor chip 13, and matched with the existing connector for use. The terminal material is brass plated with tin, and the surface plating of tin can increase the weldability of the terminal, prevent the plug from being oxidized in a humid environment for a long time, and has good corrosion resistance.

[0135] In some technical solutions, the preparation method of the above-mentioned crankshaft sensor can include:

[0136] 1) injection molding of the sensor housing 12;

[0137] 2) assembling the flexible circuit board, the sensor chip 13 and the ferromagnetic piece on the sensor housing 12;

[0138] 3) coating epoxy glue on the sensor chip 13 and the flexible circuit board;

[0139] 4) filling epoxy glue in the housing;

[0140] 5) butt joint assembly of the sensor chip 13, the flexible circuit board and the sensor housing 12;

[0141] 6) baking the integrated structure assembled at a preset temperature, for example, 120 degrees;

[0142] 7) providing a sealing ring on the integrated structure.

[0143] It should be noted that the inside of the sensor housing 12 is filled with epoxy resin to realize dustproof and waterproof sealing, and the combination of the core and the housing (filling requirements: fill the epoxy resin into the sensor housing 12, vertically assemble the core into the housing from top to bottom, bake at 120℃ for 1H after assembly to make the epoxy resin completely cured, and the core and the housing cannot be loose during the period. During the assembly process of the core and the housing, the epoxy resin cannot overflow. ) The epoxy resin filling can prevent the risk of circuit board vibration caused by high-speed rotation of the engine. The outside of the sensor housing 12 is provided with an O-shaped silica gel sealing ring for sealing interference fit with the engine mounting seat.

[0144] The crankshaft sensor prepared based on the method has the advantages of high precision, high sensitivity, good temperature stability, strong anti-interference, anti-vibration, low power consumption and the like. The above is only the technical solution of the application and is not used to limit the application. For those skilled in the art, the application can have various changes and variations. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the application shall be included in the scope of the claims of the application.

Claims

1. A crankshaft sensor circuit, comprising: A magnetoelectric induction circuit is configured to detect a target signal tooth on a crankshaft signal disk and output a corresponding pulse signal through a signal output terminal when the target signal tooth is detected. A standardization processing circuit is connected to the signal output terminal of the magnetoelectric induction circuit. The standardization processing circuit is configured to process the pulse signal into a standardized pulse signal, wherein the pulse width of the standardized pulse signal is a preset standard width.

2. The crankshaft sensor circuit according to claim 1, wherein, The magnetoelectric induction circuit includes at least one magnetoresistive resistor, and the film structure of each magnetoresistive resistor includes: Free magnetic layer; Reference magnetic layer; An insulating barrier layer is disposed between the free magnetic layer and the reference magnetic layer; An intermediate layer is disposed on the side of the reference magnetic layer away from the insulating barrier layer. The intermediate layer includes a stabilizing layer disposed close to the reference magnetic layer. The reference magnetic layer is composed of N elements, including one diffusing element. The stabilizing layer is composed of M elements, including the diffusing element. N and M are both integers greater than 1.

3. The crankshaft sensor circuit according to claim 2, wherein, The ratio between the thickness of the reference magnetic layer and the thickness of the free magnetic layer is in the range of 1.2 to 2.

5.

4. The crankshaft sensor circuit according to claim 2, wherein, The free magnetic layer and the reference magnetic layer are composed of CoxFeyRez, wherein Re is the diffusing element, and the Re element includes at least one of aluminum (Al), boron (B), selenium (Si) and manganese (Mn), and x, y and z represent the proportions of Co, Fe and Re elements, respectively.

5. The crankshaft sensor circuit according to claim 2, wherein, The thickness of the insulating barrier layer ranges from 0.8 nm to 3 nm.

6. The crankshaft sensor circuit according to claim 2, wherein, The stabilizing layer is composed of the Re element.

7. The crankshaft sensor circuit according to any one of claims 1-6, wherein, The rise time of the magnetoelectric induction circuit is in the range of 0.4μs to 2.6μs, and the fall time of the magnetoelectric induction circuit is in the range of 0.2μs to 1.2μs.

8. The crankshaft sensor circuit according to claim 1, wherein, The standardized processing circuit includes: A monostable multivibrator is connected to the signal output terminal of the magnetoelectric induction circuit. The monostable multivibrator is configured to process the pulse signal into a standardized square wave signal, wherein the pulse width of the standardized square wave signal is the preset standard width.

9. The crankshaft sensor circuit according to claim 8, wherein, The monostable multivibrator includes a set terminal, a division command terminal, and a first power input terminal. The crankshaft sensor circuit further includes: power supply; A voltage regulator circuit, the voltage regulator circuit including a second power input terminal and a power output terminal, the second power input terminal being connected to the power supply, and the power output terminal being connected to the first power input terminal; A power supply stabilization circuit includes a first resistor, a second resistor, and a third resistor. The first end of the first resistor is connected to the power output terminal and the first power input terminal, respectively. The second end of the first resistor is connected to the first end of the second resistor and the division instruction terminal, respectively. The second end of the second resistor is connected to the first end of the third resistor and the ground terminal, respectively. The second end of the third resistor is connected to the set terminal.

10. The crankshaft sensor circuit according to claim 9, further comprising: A filtering circuit is provided, comprising a first capacitor, a second capacitor, and a fourth resistor. The first terminal of the first capacitor is connected to the second power input terminal and the first terminal of the fourth resistor, respectively. The second terminal of the first capacitor is grounded. The second terminal of the fourth resistor is connected to the power supply. The first terminal of the second capacitor is connected to the first power input terminal and is grounded.

11. A crankshaft sensor, comprising the crankshaft sensor circuit as described in any one of claims 1-10.

12. The crankshaft sensor according to claim 11, comprising a sensor housing, wherein a sensor chip including a magnetoelectric induction circuit is disposed inside the sensor housing, and the sensor chip is disposed attached to the bottom of the sensor housing.

13. The crankshaft sensor according to claim 12, wherein, The bottom of the sensor housing has a receiving cavity, and the sensor chip is embedded in the receiving cavity.

14. The crankshaft sensor according to claim 12 further includes a magnet, the magnet being disposed on the side of the sensor chip away from the bottom of the sensor housing, and the magnetic field strength of the magnet having a corresponding relationship with the sensitivity parameter of the sensor chip.

15. The crankshaft sensor according to claim 14, wherein, The sensitivity parameters include signal time and / or magnetoresistance change rate, wherein the signal time is positively correlated with the magnetic field strength, and the magnetoresistance change rate is negatively correlated with the magnetic field strength.

16. The crankshaft sensor according to claim 14 or 15, wherein, The magnet is a samarium cobalt magnet, and the magnetic field strength of the ferromagnetic component is in the range of 200mT to 355mT.

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