CN105337350B - Onboard wireless charger - Google Patents

Abstract

The invention discloses a vehicle-mounted wireless charger, which has an inclined working surface, and a main coil is arranged under the working surface. The main coil charges a charging device with a secondary coil. The main coil and the secondary coil meet a wireless charging standard, and The size of the working surface and the position of the main coil make the overlapping area of the secondary coil and the main coil meet the requirements of the wireless charging standard when the charging device is placed on the working surface. The invention achieves the effect that the mobile phone is always in the effective charging area as long as it can be placed on the working surface by setting an inclined working surface, limiting the size of the working surface and locating the position of the main coil in the working surface.

Description

Car Wireless Charger

technical field

The present invention relates to a vehicle auxiliary device, more specifically, to a vehicle wireless charger.

Background technique

Electronic devices are becoming more and more popular, and the charging problem of electronic devices is also becoming more and more prominent. With the development of wireless charging technology, it is also hoped that cars will have wireless charging capabilities.

The emergence of on-board wireless charging equipment is in line with the current technological development trend. The on-board wireless charging device also needs to comply with a certain wireless charging standard, so as to be used in conjunction with the charging device that also meets the wireless charging standard. At present, the most commonly used charging device is a mobile phone, and the more common wireless charging standard in mobile phones is the Qi wireless charging standard.

According to the Qi wireless charging standard, the main coil is arranged in the form of three coils, and the three coils are superimposed to form an approximately rectangular main coil area. The secondary coil and the main coil in the mobile phone can be charged if they meet a certain overlapping area requirement. Usually, the secondary coil in the mobile phone is located in the middle area of the mobile phone, that is, the geometric center of the secondary coil overlaps with the geometric center of the mobile phone. In the conventional technology, the three-coil structure is also centrally arranged on the working surface (A surface) of the wireless charging device, that is, the geometric center of the three-coil structure overlaps with the geometric center of the A surface. Then, a price limiting mechanism is set on the working surface, and the limiting mechanism is used to limit the position of the mobile phone on the A surface, so that the mobile phone can always be in the effective charging area.

For vehicle-mounted equipment, the issue of driving safety needs to be considered, and drivers are not expected to be distracted to operate these auxiliary equipment. Therefore, the existence of these limit mechanisms is not suitable. These limit mechanisms require the driver to be distracted to operate, which is likely to cause potential safety hazards.

Contents of the invention

The purpose of the present invention is to provide a vehicle-mounted wireless charger. Through the size design of the working surface and the arrangement position of the main coil, the mobile phone is always within the effective charging range when it is placed on the working surface.

According to an embodiment of the present invention, a vehicle-mounted wireless charger is proposed, which has an inclined working surface, and a main coil is arranged under the working surface, and the main coil is used for charging a charging device with a secondary coil. Wireless charging standard, and the size of the working surface and the position of the main coil make the overlapping area of the secondary coil and the main coil meet the requirements of the wireless charging standard when the charging device is placed on the working surface.

In one embodiment, the charging device is a mobile phone, the wireless charging standard is the Qi wireless charging standard, the main coil arranged below the working surface is a three-coil structure conforming to the Qi standard, the plane of the main coil is parallel to the working surface, and the mobile phone is placed above the working surface .

In one embodiment, the inclination angle α of the working surface satisfies α>arctgμ, where μ is the coefficient of friction between the surface of the working surface and the casing of the mobile phone.

In one embodiment, the inclination angle α satisfies 20°<α<45°.

In one embodiment, the size of the working surface meets the following conditions:

The width W satisfies W1≤W<L2, where W1 is the maximum width of a mobile phone with Qi wireless charging function, and L2 is the minimum length of a mobile phone with Qi wireless charging function;

The length L satisfies L1≤L≤2(l'm+1/2L2), where L1 is the maximum length of a mobile phone with Qi wireless charging function, L2 is the minimum length of a mobile phone with Qi wireless charging function, l'm=D -A', wherein D is a fixed value, which is half of the total length of the main coil forming the three-coil structure, and A' is a fixed value, which is half of the length of the secondary coil.

In one embodiment, the working surface is rectangular, and the working surface is inclined along the width direction of the rectangle.

In one embodiment, the arrangement position of the main coil satisfies the following conditions:

The distance J between the central axis of the main coil forming the three-coil structure in the length direction and any side of the working surface in the length direction satisfies the following conditions:

1/2L1≤J≤l'm+1/2L2, where L1 is the maximum length of a mobile phone with Qi wireless charging function, L2 is the minimum length of a mobile phone with Qi wireless charging function, l'm=D-A', Wherein D is a fixed value, which is half of the total length of the main coil forming the three-coil structure, and A' is a fixed value, which is half of the length of the secondary coil;

The distance H between the central axis of the main coil forming the three-coil structure in the width direction and the bottom edge of the working surface in the width direction satisfies the following conditions:

1/2·W1-lm≤H≤1/2·W2+lm, where W1 is the maximum width of a mobile phone with Qi wireless charging function, L2 is the minimum width of a mobile phone with Qi wireless charging function, lm=A+B-C ; Wherein A is a fixed value, which is half the length of the main coil; B is a variable value, which is the distance from the edge of the secondary coil beyond the edge of the main coil toward the bottom of the A surface, and the value range of B is less than the width of the secondary coil 1/3; C is a fixed value, which is half of the width of the secondary coil.

In one embodiment, there are auxiliary markings on the surface of the working surface, the auxiliary markings display at least one of the following:

The position of the central axis of the three-coil structure in the length direction, the central axis of the three-coil structure in the width direction, or the geometric center of the three-coil structure.

In one embodiment, the vehicle wireless charger is provided with a frame along the bottom edge of the working surface.

In one embodiment, the on-board wireless charger is provided with a frame along the outer contour of the working surface.

The invention achieves the effect that the mobile phone is always in the effective charging area as long as it can be placed on the working surface by setting an inclined working surface, limiting the size of the working surface and locating the position of the main coil in the working surface.

Description of drawings

The above and other features, properties and advantages of the present invention will become more apparent from the following description in conjunction with the accompanying drawings and embodiments, in which the same reference numerals represent the same features throughout, wherein:

Figure 1a reveals the size parameters of the main coil in the Qi wireless charging standard.

Figure 1b reveals the layout scheme of the three-coil standard in the Qi wireless charging standard.

Figure 1c reveals the size parameters of the secondary coil in the Qi wireless charging standard.

Fig. 2 discloses a schematic side view of the vehicle wireless charger according to an embodiment of the present invention.

Fig. 3-Fig. 6 disclose the basis for calculating the size of the working surface and the position of the main coil of the on-board wireless charger according to an embodiment of the present invention.

detailed description

The vehicle wireless charger of the present invention meets the Qi wireless charging standard. The vehicle-mounted wireless charger has three coils arranged on its charging working surface, that is, directly below the A surface, and the size and layout of the three coils are arranged according to the three-coil standard of the Qi wireless charging standard.

Referring to Figure 1a and Figure 1b, the three-coil standard in the Qi wireless charging standard is as follows. Referring to FIG. 1a and Table 1 below, the three coils have the same size and number of winding turns. The three coils are located in the charger and are called main coils.

Table 1

parameter Identified in Figure 1a value Outer profile length d _ol 53.2±0.5mm Inner profile length d _il 27.5±0.5mm Outer profile width d _ow 45.2±0.5mm Inner profile width _iw 19.5±0.5mm thickness d _c 1.5±0.5mm Number of turns per layer none 12 laps layers none 1 story

Figure 1b reveals that according to the Qi wireless charging standard, the arrangement of the three coils is: based on the reference coordinate system X/Y coordinate system shown in Figure 1b, the length direction of the first coil C1 and the second coil C2 is along the X axis , the length direction of the third coil C3 is along the Y axis, and the X axis and the Y axis are perpendicular to each other. The first coil C1 and the second coil C2 are aligned with each other in the Y-axis direction, and in the X-axis direction, the distance d _oo between the central axis in the width direction of the first coil C1 and the central axis in the width direction of the second coil C2 is: 49.2±4mm. The central axis in the width direction of the third coil C3 is aligned with the central axes in the length direction of the first coil C1 and the second coil C2. In the X-axis direction, the central axis of the third coil C3 in the longitudinal direction is located in the middle of the central axis of the first coil C1 in the width direction and the central axis of the second coil C2 in the width direction. The distance _doe between the central axis in the length direction of the third coil C3 and the central axis in the width direction of the first coil C1 is 49.2±4mm, and the distance between the central axis in the length direction of the third coil C3 and the central axis in the width direction of the second coil C2 The distance between them is also 49.2±4mm.

The auxiliary coil is installed in the device to be charged, and is used to cooperate with the main coil to receive the electromagnetic energy output by the main coil to charge the device to be charged. Referring to Figure 1c, the secondary coil standard in the Qi wireless charging standard is as follows. Referring to Figure 1c and Table 2 below,

Table 2

parameter Identified in Figure 1c value Outer profile length d' _ol 44.25±0.25mm Inner profile length d' _il 28.75±0.25mm Outer profile width d' _ow 30.25±0.25mm Inner profile width d' _iw 14.75±0.25mm thickness d' _c 0.6mm Number of turns per layer none 14 laps layers none 1 story

According to the Qi wireless charging standard, the main coil and the secondary coil need to meet a certain overlapping area in order to achieve the required charging efficiency. If the overlapping area of the main coil and the secondary coil does not meet the requirements specified in the Qi wireless charging standard, the charging efficiency will decrease. When the overlapping area of the main coil and the secondary coil is less than 2/3, the charging efficiency drops to 0. Therefore, the outer dimension of surface A needs to meet the following conditions. When the mobile phone to be charged is placed on surface A, the overlapping area of the secondary coil and the main coil in the mobile phone is not less than 2/3. Here 2/3 is based on the area of the auxiliary coil, that is, at least 2/3 of the area of the auxiliary coil overlaps with the main coil of the three-coil structure to meet the charging conditions.

One of the purposes of the vehicle-mounted wireless charger of the present invention is to realize the "free placement" of the mobile phone, that is, no matter how the mobile phone is placed on the working surface of the charger, the mobile phone can be charged without the problem of the placement position. , The overlapping area of the main coil and the auxiliary coil is too small to cause the problem that charging cannot be carried out.

In order to achieve "free placement", the present invention starts from the following aspects: reasonably set the size of the A surface, so that the mobile phone can only be placed on the A surface in one direction, and the mobile phone cannot be placed in the A surface in the wrong direction; When the mobile phone is placed on the A side, it will automatically move to a certain fixed position, so no matter where the mobile phone is placed on the A side, the mobile phone will eventually move to a predetermined position. At this point, the present invention has carried out following design for A side:

The charging working surface of the vehicle wireless charger of the present invention, that is, the A surface is placed obliquely. Fig. 2 discloses a schematic side view of the vehicle wireless charger according to an embodiment of the present invention. Since the A surface is placed at an angle, when the mobile phone is placed on the A surface, it will receive the effects of gravity and friction. As shown in Figure 2, it is assumed that the friction coefficient between the mobile phone and the surface A is μ. Plane A forms a certain angle α with the horizontal plane. When the angle α reaches a certain value, the mobile phone will slide down along the plane A due to gravity. At this time, the gravity G of the mobile phone faces the mobile phone along A. The force F=mg·sinα is greater than the frictional resistance f=μ·mg·cosα that the mobile phone receives on the rubber plane, that is, mg·sinα>μ·mg·cosα, calculated tgα>μ. Therefore, when the inclination angle of surface A > arctgμ, the mobile phone will overcome the friction force under the action of gravity and slide to the bottom of surface A to realize the positioning function. Most mobile phone casings are made of plastic or smooth metal, while the A-side material of the car wireless charger is rubber. The coefficient of friction μ is about 0.36, so the inclination angle α of surface A is usually >20°. Considering the stability and safety of driving, the inclination angle α of surface A is usually not greater than 45°.

The tilted side A solves the problem of automatic positioning of the mobile phone on the A side. After the mobile phone is placed on the A side, it will automatically slide to the bottom of the A side. It should be noted that in the following descriptions and related calculations, the surface A is inclined along its short side, that is, along the width direction.

Next, it is necessary to solve the outer contour size of the A surface and the positioning of the main coil on the A surface, so as to ensure that the mobile phone can meet the area overlap requirements of the main coil and the secondary coil on the A surface. First collect the shape and size data of mainstream mobile phones with Qi wireless charging function. In the following description, the size examples listed are all based on the size of mainstream mobile phones on the market when this application is filed. Those skilled in the art need to understand that with the continuous updating of mobile phones, the sizes of mainstream mobile phones will also change. Changes, the protection scope of the present invention should be based on the disclosed design solutions, rather than limited to the enumerated dimensions. Those skilled in the art can update the size of the wireless charger according to the solution of the present invention when the size of the mainstream mobile phone at that time is updated. In this article, among the mobile phones with wireless charging function, the one with the largest length is ZTE MAX with a length of 164mm. The one with the largest width is the Nokia Lumia 1520 at 86mm. The one with the smallest width is the IPONE 5 with a width of 61mm. The one with the smallest length is the IPHONE 4 with a length of 125mm. In the following size examples, the above-mentioned maximum cell phone length L1, maximum cell phone width W1, minimum cell phone length L2, and minimum cell phone width W2 will be taken as examples.

When the mobile phone is placed on surface A, it first needs to meet the direction requirements: the length direction of the mobile phone should be consistent with the length direction of surface A. The current mainstream mobile phones basically have a nearly rectangular outer contour, and the A surface is also roughly rectangular, so the mobile phone is placed on the A surface in such a way that the length direction is consistent with the A surface. Therefore, the width W of surface A needs to satisfy W≥W1, so that the mobile phone with the largest width can be smoothly put in. At the same time, W<L2, which can ensure that the mobile phone will not be placed on the A surface in the wrong direction. If the mobile phone is placed on the A surface in the wrong direction (that is, the length direction of the mobile phone is consistent with the width direction of the A surface), then It will cause the overlapping area of the secondary coil and the main coil in the mobile phone to be less than 2/3, so that the mobile phone cannot be charged. Because W<L2, the mobile phone cannot be placed on the A side in the wrong direction. At present, the mainstream mobile phones on the market have a length larger than a width, and there is a large gap between W1 and L2, so the situation of W1>L2 is not considered for the time being. Therefore, the dimension of the width W of the A surface is W1≦W<L2.

After satisfying the aforementioned conditions, the placement of the mobile phone on the A surface has the following characteristics: the mobile phone is placed on the A surface, and the length direction of the mobile phone is consistent with the length direction of the A surface. And, no matter where the mobile phone is placed on the A surface, the mobile phone will slide to the bottom of the A surface. Next, it is necessary to further limit the size of the A surface, and to position the main coil on the A surface, so as to meet the condition that the overlapping area of the secondary coil and the main coil in the mobile phone is not less than 2/3. In the following description, the geometric center of the secondary coil overlaps with the geometric center of the mobile phone. Since the A side is inclined along its short side, that is, along the width direction, when the mobile phone is placed on the A side, keep the same direction as the A side, and the mobile phone is also a short side (that is, there is an inclination in the width direction).

Fig. 3-Fig. 6 disclose the basis for calculating the size of the working surface and the position of the main coil of the on-board wireless charger according to an embodiment of the present invention. In the illustrations shown in Figures 3-6, according to the set reference coordinate system, the X'Y' coordinate system, the tilt is along the X' axis, the side on the left side of the X' axis is the high point, and the X' axis The edge on the right is the low point. When the mobile phone is placed on side A, it will slide down to the bottom of side A, which is close to the right side of side A as shown in the figure.

In the X' direction, the distance H between the central axis X2 of the main coil and the bottom edge of the A surface (the rightmost edge of the A surface shown in Figure 3 and Figure 4) should meet the following conditions: when the mobile phone When placed on surface A and slide down to the lowest point of surface A, the overlapping area of the secondary coil (mobile phone charging coil) and the main coil (coil on the wireless charging device) cannot be less than 2/3.

Referring to Figure 3, in order to meet the requirement that the overlapping area of the secondary coil (mobile phone charging coil) and the main coil (coil on the wireless charging device) cannot be less than 2/3, the central axis X1 of the secondary coil and the three coils of the main coil The distance Im between the central axes X2 of the structure should meet the following conditions:

The distance between X1 and X2 (no matter which side of X1 is biased towards X2), Im cannot exceed an upper limit value, exceeding the upper limit value will cause the overlapping area of the secondary coil and the main coil to be less than 2/3. Continuing to refer to the accompanying drawings, Im can be calculated as follows

lm=A+B-C;

Among them, A is a fixed value, which is half the length of the main coil; B is a variable value, which is the distance from the edge of the secondary coil to the edge of the main coil in the direction towards the bottom of surface A, and the value range of B needs to be less than a maximum value , the maximum value is 1/3 of the width of the secondary coil; C is a fixed value, which is half of the width of the secondary coil, and the values of A, B, and C are respectively:

A=1/2dol, B(max)=1/3d'ow, C=1/2d'ow;

According to B(max), lm(max) can be calculated:

lm(max)=A+B(max)-C=1/2dol+1/3d'ow-1/2d'ow=1/2·53.2+1/3·30.25-1/2·30.25=21.56± 0.25mm.

lm≤21.56±0.25mm.

When the mobile phone is placed on surface A, it is also necessary to consider the limitation of the size of the mobile phone itself on the location of the mobile phone: after the mobile phone with the minimum width is placed on surface A, the distance between the central axis X1 of the mobile phone and the central axis X2 of the main coil Distance (X1 deviates from X2 to the base of A face) should be no greater than 1m. After the mobile phone with the maximum width is placed on the A surface, the distance between the central axis X1 of the mobile phone and the main coil central axis X2 (X1 is offset from X2 to the top edge of the A surface) should not be greater than Im.

From this calculation, in the X' direction, the distance H between the central axis X2 of the main coil and the bottom edge of the A surface satisfies:

1/2·W1-lm≤H≤1/2·W2+lm;

Wherein, W1 is the maximum mobile phone width, W2 is the minimum mobile phone width, calculated as the maximum mobile phone width W1=86mm, and the minimum mobile phone width W2=61mm.

H≤1/2·W2+lm, or Hmax=1/2·W2+lm(max)=61mm+(21.56±0.25mm). Figure 3 reveals the above calculation process. Based on the minimum mobile phone width W2, the maximum value of H, ie the upper limit, can be obtained.

H≥1/2·W1-lm, or Hmin=1/2·W1-lm(max)=86mm-(21.56±0.25mm). Figure 4 reveals the above calculation process. Based on the maximum mobile phone width W1, the minimum value of H can be obtained, that is, the lower limit value.

The dimension L of the surface A in the length direction needs to meet the following requirements: L≥L1, that is, greater than the maximum length of the mobile phone. Correspondingly, the distance J between the side of surface A and the central axis in the length direction of the main coil needs to satisfy J≥1/2L1, that is, Jmin=1/2L1.

In the Y' direction, the distance L between the central axis Y2 of the main coil and the side of the A surface (the side of any side) should also meet the following conditions: when the mobile phone is placed on the A surface, the secondary coil (Mobile phone charging coil) and the main coil (coil on the wireless charging device) overlap area should not be less than 2/3.

Referring to Figure 6, in order to meet the requirement that the overlapping area of the secondary coil (mobile phone charging coil) and the main coil (coil on the wireless charging device) cannot be less than 2/3, the central axis Y1 of the secondary coil and the three coils of the main coil The distance I'm between the central axis Y2 of the structure should meet the following conditions:

The distance between Y1 and Y2 (no matter which side Y1 is biased to Y2), I'm can not exceed an upper limit, exceeding the upper limit will cause the overlapping area of the secondary coil and the main coil to be less than 2/3. Continuing to refer to the accompanying drawings, I'm can be calculated as follows

l'm=D-A';

Wherein D is a fixed value, which is half of the total length of the main coil, that is, half of the total length in the length direction of the combination of the three main coils forming the three-coil structure. A' is also a fixed value, which is half the length of the secondary coil. The values of D and A' are respectively:

D=1/2 (doo+dow), A'=1/2d'ol;

l'm＝1/2·(doo+dow)-1/2d'ol＝1/2·(49.2±4mm)+1/2·(45.2±0.5mm)-1/2·(44.25±0.25mm )=(47.2±2mm)–(22.125±0.125m)=25.075±2mm.

When the mobile phone is placed on surface A, it is also necessary to consider the limitation of the size of the mobile phone itself on the location of the mobile phone: after the mobile phone with the minimum length is placed on surface A, the distance between the central axis Y1 of the mobile phone and the central axis Y2 of the main coil The distance (the offset of Y1 from Y2 to any side of A plane) should not be greater than I'm.

J≤l'm+1/2L2.

L1 is the maximum mobile phone length, and L2 is the minimum mobile phone length, calculated with the maximum mobile phone length L1=164mm and the minimum mobile phone length L2=125mm.

J≤l'm+1/2L2, or Jmax=l'm+1/2L2=(25.075±2mm)+1/2·125mm. Figure 6 reveals the above calculation process. Based on the minimum mobile phone length L2, the maximum value of L, ie the upper limit, can be obtained.

J≥1/2L1, or Jmin=1/2·L1=1/2·164mm. Figure 5 reveals the above calculation process. Based on the maximum mobile phone length L1, the minimum value of L, ie the lower limit, can be obtained.

Therefore, the distance J between the central axis Y2 in the length direction of the main coil and any side of the A surface satisfies: 1/2L1≤J≤l'm+1/2L2.

The dimension L in the longitudinal direction of surface A satisfies L1≤L≤2Jmax, that is, L1≤L≤2(l'm+1/2L2).

On the whole,

The working surface of the vehicle-mounted wireless charger of the present invention is placed obliquely, and the inclination angle α satisfies α>arctgμ, where μ is the friction coefficient between the surface of the working surface and the shell of the mobile phone. Usually, 20°<α<45°. The working surface is inclined along the width direction.

The dimensions of the working face meet the following conditions:

The width W satisfies W1≤W<L2, where L2 is the minimum length of a mobile phone with Qi wireless charging function.

The length L satisfies L1≤L≤2(l'm+1/2L2), where L1 is the maximum length of a mobile phone with Qi wireless charging function, L2 is the minimum length of a mobile phone with Qi wireless charging function, l'm=25.075 ±2mm.

The main coil is arranged under the working surface. The main coil is a three-coil structure. The size of the main coil and the arrangement of the three coils meet the Qi standard. The three coils are parallel to the working surface.

Wherein, the distance J between the central axis of the main coil forming the three-coil structure in the length direction and any side (short side) of the working surface in the length direction satisfies the following conditions:

1/2L1≤J≤l’m+1/2L2, where L1 is the maximum length of a mobile phone with Qi wireless charging function, L2 is the minimum length of a mobile phone with Qi wireless charging function, l’m=25.075±2mm.

The distance H between the central axis of the main coil forming the three-coil structure in the width direction and the bottom edge (lower long side) of the working surface in the width direction satisfies the following conditions:

1/2·W1-lm≤H≤1/2·W2+lm, where W1 is the maximum width of a mobile phone with Qi wireless charging function, L2 is the minimum width of a mobile phone with Qi wireless charging function, lm≤21.56±0.25 mm.

The car wireless charger can set a frame along the outer contour of the working surface to clarify the range of the outer contour. Since the car wireless charger is placed obliquely, the frame at the bottom of the working surface is necessary, and the frames on the other three sides are optional.

In addition, there may be auxiliary marks on the surface of the working surface, which may display the central axis of the three-coil structure in the length direction, the central axis in the width direction, or the position of its geometric center.

The invention achieves the effect that the mobile phone is always in the effective charging area as long as it can be placed on the working surface by setting an inclined working surface, limiting the size of the working surface and locating the position of the main coil in the working surface.

The above-mentioned embodiments are provided for those who are familiar with the field to implement or use the present invention, and those who are familiar with the art can make various modifications or changes to the above-mentioned embodiments without departing from the inventive idea of the present invention. The scope of protection of the present invention is not limited by the above-mentioned embodiments, but should be the maximum scope consistent with the innovative features mentioned in the claims.

Claims (8)

1. a kind of onboard wireless charger, it is characterised in that with the working face being obliquely installed, working face arranged beneath has main line Circle, the main coil is the charging equipment charging with secondary coil, and the main coil, secondary coil meet Qi wireless charging standards, and When the size of the working face and the position of main coil make it that the charging equipment is placed on working face, the weight of secondary coil and main coil Close the requirement that area meets Qi wireless charging standards；

The charging equipment is mobile phone, and the main coil of the working face arranged beneath is the three-winding for meeting Qi wireless charging standards Structure, main coil plane is parallel with working face, and the mobile phone is placed in above working face；

The size of the working face meets following conditions：

Width W meets W1≤W<L2, wherein W1 are the Breadth Maximum for the mobile phone for possessing Qi wireless charging functions, L2 for possess Qi without The minimum length of the mobile phone of line charge function；

Length L meets L1≤L≤2 (l ' m+1/2L2), and wherein L1 is the maximum length for the mobile phone for possessing Qi wireless charging functions, L2 is the minimum length for the mobile phone for possessing Qi wireless charging functions, and l ' m=D-A ', wherein D are fixed values, to form three-winding knot The half of the main coil total length of structure, A ' is fixed value, is the half of secondary coil length.

2. onboard wireless charger as claimed in claim 1, it is characterised in that the tilt angle alpha of the working face meets α ＞ Arctg μ, wherein μ are the coefficient of friction between face surface and phone housing.

3. onboard wireless charger as claimed in claim 2, it is characterised in that the tilt angle alpha meets 20 °<α<45°.

4. onboard wireless charger as claimed in claim 1, it is characterised in that the working face is rectangular, working face is along square The width of shape is tilted.

5. onboard wireless charger as claimed in claim 4, it is characterised in that the position of the main coil meets following Condition：

Formed the main coil axis in the longitudinal direction of three-winding structure apart from working face in the longitudinal direction any one Side apart from J meets following conditions：

1/2L1≤J≤l ' m+1/2L2, wherein L1 are the maximum length for the mobile phone for possessing Qi wireless charging functions, and L2 is to possess Qi The minimum length of the mobile phone of wireless charging function, wherein l ' m=D-A ', D are fixed values, to form the main coil of three-winding structure The half of total length, A ' is fixed value, is the half of secondary coil length；

Form base of the axis apart from working face in the direction of the width of the main coil of three-winding structure in the direction of the width Following conditions are met apart from H：

1/2W1-lm≤H≤1/2W2+lm, wherein W1 are the Breadth Maximum for the mobile phone for possessing Qi wireless charging functions, and W2 is Possess the minimum widith of the mobile phone of Qi wireless charging functions, lm=A+B-C；Wherein A is fixed value, to form three-winding structure The half of main coil width；B is variable value, is that towards on the direction on A faces base, the edge of secondary coil is beyond main coil edge Distance, B span is less than the 1/3 of secondary coil width；C is fixed value, is the half of secondary coil width.

6. onboard wireless charger as claimed in claim 5, it is characterised in that there is aid mark on the surface of working face, Aid mark shows at least one following：

Three-winding structure axis in the longitudinal direction, three-winding structure axis in the direction of the width or its three-winding The location of geometric center of structure.

7. onboard wireless charger as claimed in claim 4, it is characterised in that the onboard wireless charger is along working face Base is provided with frame.

8. onboard wireless charger as claimed in claim 7, it is characterised in that the onboard wireless charger is along working face Outline is provided with frame.