CN217716728U - Bicycle crank power meter for measuring force-exerting direction and position - Google Patents
Bicycle crank power meter for measuring force-exerting direction and position Download PDFInfo
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- CN217716728U CN217716728U CN202220531843.4U CN202220531843U CN217716728U CN 217716728 U CN217716728 U CN 217716728U CN 202220531843 U CN202220531843 U CN 202220531843U CN 217716728 U CN217716728 U CN 217716728U
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Abstract
The utility model relates to a measure technical field's a crank power meter for bicycle of direction of exerting force, position, including a plurality of with analytical instrument signal of telecommunication connection, paste the dress at the foil gage on crank main part surface, all foil gages divide into four groups at least, each group foil gage component half-bridge or full-bridge circuit, measure moment of flexure M1, moment of flexure M2, moment of flexure M3 respectively, along crank main part length direction's axial force Fz. The utility model discloses having optimized the overall arrangement of foil gage, having added four at least group's foil gages in the suitable position of crank main part, the electric bridge of four groups of structures can realize the effect position of trampling force and the decoupling zero of not equidirectional weight under rectangular coordinate system through corresponding formula operation to obtain the trampling force direction.
Description
Technical Field
The utility model relates to a measure technical field, particularly, be a crank power meter for bicycle of survey direction of exerting oneself, position.
Background
The existing strain gauge pasting mode of the bicycle crank power meter is to paste a group of strain gauges on the inner side of a crank, construct a group of bridge circuits, obtain torque for driving the crank to rotate when being trampled through measuring output signals of a bridge, and cannot detect other two components of a trampling force F in a rectangular coordinate system and the action position of the trampling force on a pedal shaft.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a survey crank power meter for bicycle of direction of exerting oneself, position through constructing four electric bridges of group, realizes the decoupling zero to the effect position of trampling force and not equidirectional component under rectangular coordinate system to obtain the trampling force direction.
The purpose of the utility model is realized like this: a crank power meter for bicycle for measuring the force direction and position comprises a plurality of strain gauges which are connected with an electric signal of an analyzer and attached to the surface of a crank main body, wherein all the strain gauges are divided into at least four groups;
presetting a bending moment M1 measuring position which is away from the axis of a pedal hole by Z1 along the length direction of a crank main body, arranging at least one first strain gauge and at least one second strain gauge at the bending moment M1 measuring position, wherein the first strain gauge and the second strain gauge are respectively attached to the outer side and the inner side of the crank main body to form a first group of strain gauges, and the first group of strain gauges form a half-bridge or full-bridge circuit;
presetting a bending moment M2 measuring position at which the distance Z2 between the length direction of the crank main body and the axis of a pedal hole is preset, and arranging at least one third strain gauge and at least one fourth strain gauge at the bending moment M2 measuring position, wherein the third strain gauge and the fourth strain gauge are respectively attached to the outer side and the inner side of the crank main body to form a second group of strain gauges, and the second group of strain gauges form a half-bridge or full-bridge circuit;
presetting a measuring position for measuring a bending moment M3 caused by a force Fx for driving the crank to rotate, and arranging at least one fifth strain gauge and at least one sixth strain gauge at the measuring position for the bending moment M3, wherein the fifth strain gauge and the sixth strain gauge are attached to the inner side of the crank main body to form a third group of strain gauges, and the third group of strain gauges form a half-bridge or full-bridge circuit;
the measuring position for measuring the axial force Fz along the length direction of the crank main body is preset, the measuring position for measuring the axial force Fz is positioned between the measuring position for measuring the bending moment M1 and the measuring position for measuring the bending moment M2, at least one seventh strain gauge and at least one eighth strain gauge are arranged at the measuring position for measuring the axial force Fz, the seventh strain gauge and the eighth strain gauge are respectively attached to the outer side and the inner side of the crank main body to form a fourth group of strain gauges, and the fourth group of strain gauges form a half-bridge or full-bridge circuit.
The beneficial effects of the utility model reside in that:
the layout of the strain gauges is optimized, at least four groups of strain gauges are added at proper positions of the crank main body to construct four groups of electric bridges, decoupling of acting positions of treading force and components in different directions under a rectangular coordinate system can be achieved through corresponding formula operation, and the direction of the treading force is obtained.
Drawings
Fig. 1 is a structural view of the present invention.
Fig. 2 is an outside view of the present invention.
Fig. 3 is a first force analysis diagram of the crank.
FIG. 4 is a second force analysis plot of the crank.
Fig. 5 is a schematic diagram of a bridge formed by the first strain gauge and the second strain gauge.
Fig. 6 is a schematic diagram of a bridge formed by a third strain gage and a fourth strain gage.
Fig. 7 is a schematic diagram of a bridge formed by a fifth strain gauge and a sixth strain gauge.
Fig. 8 is a schematic diagram of a bridge formed by a seventh strain gage and an eighth strain gage.
In the figure, 1 crank main body, 2 bicycle axle center holes, 3 pedal holes, 4 first strain gauges, 5 second strain gauges, 6 third strain gauges, 7 fourth strain gauges, 8 fifth strain gauges, 9 sixth strain gauges, 10 seventh strain gauges, 11 eighth strain gauges and 12 pedal shafts.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments.
In this embodiment, the rectangular coordinate system is set as follows:
the axial midpoint of the pedal hole 3 is taken as the origin, the line along the length direction of the crank body 1 is taken as the z-axis, the axial line of the pedal shaft 12 is taken as the y-axis, and the action line of the horizontal component force for driving the crank to rotate is taken as the x-axis (forwards).
The pedal force point is located at a position on the axis of the pedal shaft 12, which is y0 away from the origin of coordinates.
As shown in fig. 1 to 4, a bicycle crank dynamometer for measuring a force application direction and a force application position includes a plurality of strain gauges attached to a surface of a crank body 1 and electrically connected to an analyzer, and all the strain gauges are divided into four groups (more than four groups can be considered).
A bending moment M1 measuring position which is far from the axis of the pedal hole 3 by Z1 along the length direction of the crank main body 1 is preset, a first strain gauge 4 and a second strain gauge 5 are arranged at the bending moment M1 measuring position, the first strain gauge 4 and the second strain gauge 5 are respectively attached to the outer side and the inner side of the crank main body 1 to form a first group of strain gauges, the first group of strain gauges form a half-bridge or full-bridge circuit, and as shown in fig. 5, the first strain gauge 4 and the second strain gauge 5 are in a difference relation and used for measuring the bending moment M1 which is far from the pedal shaft 12 and is far from the Z1.
A bending moment M2 measuring position of a distance Z2 between the length direction of the crank main body 1 and the axis of the pedal hole 3 is preset, a third strain gauge 6 and a fourth strain gauge 7 are arranged at the bending moment M2 measuring position, the third strain gauge 6 and the fourth strain gauge 7 are respectively attached to the outer side and the inner side of the crank main body 1 to form a second group of strain gauges, the second group of strain gauges form a half-bridge or full-bridge circuit, and as shown in fig. 6, the third strain gauge 6 and the fourth strain gauge 7 are in a difference relation and used for measuring the bending moment M2 at the distance Z2 from the pedal shaft 12.
A measuring position for measuring a bending moment M3 caused by a force Fx for driving the crank to rotate is preset, a fifth strain gauge 8 and a sixth strain gauge 9 are arranged at the measuring position for the bending moment M3, the fifth strain gauge 8 and the sixth strain gauge 9 are attached to the inner side of the crank main body 1 to form a third group of strain gauges, the third group of strain gauges form a half-bridge or full-bridge circuit, as shown in FIG. 7, the fifth strain gauge 8 and the sixth strain gauge 9 are in a difference relationship, and the bending moment M3 caused by the force Fx for driving the crank to rotate is measured.
The method is characterized in that a measuring position for measuring the axial force Fz along the length direction of the crank main body 1 is preset, the measuring position for the axial force Fz is located between a measuring position for bending moment M1 and a measuring position for bending moment M2, a seventh strain gage 10 and an eighth strain gage 11 are arranged at the measuring position for the axial force Fz, the seventh strain gage 10 and the eighth strain gage 11 are respectively attached to the outer side and the inner side of the crank main body 1 to form a fourth group of strain gages, the fourth group of strain gages form a half-bridge or full-bridge circuit, as shown in FIG. 8, the seventh strain gage 10 and the eighth strain gage 11 are in a sum relation, and the axial force F along the crank direction is measured.
As shown in fig. 3 and 4, on the inner side surface of the crank body 1, a second strain gauge 5, an eighth strain gauge 11 and a fourth strain gauge 7 are sequentially arranged in the center on a connecting line from the center of the bicycle axle hole 2 to the center of the pedal hole 3; on the inner side surface of the crank body 1, a fifth strain gage 8 and a sixth strain gage 9 are respectively positioned at two side directions of a connecting line of the center of the bicycle axle center hole 2 and the center of the pedal hole 3; on the inner side surface of the crank body 1, the sixth strain gauge 9 and the fifth strain gauge 8 are respectively arranged at the left side and the right side of an eighth strain gauge 11; as shown in fig. 3, on the inner surface of the crank body 1, the second strain gage 5, the fifth strain gage 8, the fourth strain gage 7 and the sixth strain gage 9 are distributed in a diamond shape, and the eighth strain gage 11 is located at the intersection of two diagonals of the diamond shape.
As shown in fig. 2 and 4, on the outer side surface of the crank body 1, a first strain gage 4, a seventh strain gage 10 and a third strain gage 6 are sequentially arranged in the center on a connecting line from the center of the bicycle axle hole 2 to the center of the pedal hole 3; the distance between the seventh strain gage 10 and the axis of the pedal shaft 12 is equal to the distance between the eighth strain gage 11 and the axis of the pedal shaft 12, the seventh strain gage 10 is opposite to the eighth strain gage 11, the first strain gage 4 is opposite to the second strain gage 5, and the third strain gage 6 is opposite to the fourth strain gage 7.
The corresponding relation between the measuring signal and the force (moment) is as follows:
M1＝K1*A1；
M2＝K2*A2；
M3＝K3*A3；
F＝K4*A4；
the reference numeral A1 denotes signals collected by the first strain gage 4 and the second strain gage 5 in the first group of strain gages, A2 denotes signals collected by the third strain gage 6 and the fourth strain gage 7 in the second group of strain gages, A3 denotes signals collected by the fifth strain gage 8 and the sixth strain gage 9 in the third group of strain gages, and A4 denotes signals collected by the seventh strain gage 10 and the eighth strain gage 11 in the fourth group of strain gages. K1 is the coefficient for calculating bending moment M1 using the first set of strain gage signals, K2 is the coefficient for calculating bending moment M2 using the second set of strain gage signals, K3 is the coefficient for calculating bending moment M3 using the third set of strain gage signals, and K4 is the coefficient for calculating axial force F using the fourth set of strain gage signals. As shown in FIGS. 5-8, A1-4 is the amount of output voltage Ei; e0 is the actuation voltage.
The bending moments M1, M2, M3 and the axial force F can be expressed in force components as:
M1＝Fy*z1+Fz*y0；
M2＝Fy*z2+Fz*y0；
M3＝Fx*L；
F＝Fz。
where Fx is a component force of the tread force in the x direction, fy is a component force of the tread force in the y0 direction, fz is a component force of the tread force in the z direction, y0 is an action position of the tread force (as shown in fig. 4), and L is a crank length.
The component and position of the pedaling force can be calculated according to the following formula:
Fx＝K3*A3/L；
Fy＝(M1-M2)/(z1-z2)；
Fz＝K4*A4；
y0＝【1/(K4*A4)】*【(K2*A2*z1-K1*A1*z2)/(z1-z2)】。
the above are preferred embodiments of the present invention, and those skilled in the art can make various changes or improvements on the above embodiments without departing from the general concept of the present invention, and such changes or improvements should fall within the protection scope of the present invention.
Claims (7)
1. A bicycle crank power meter for measuring the force application direction and position comprises a plurality of strain gauges which are connected with an electric signal of an analytical instrument and attached to the surface of a crank main body (1), and is characterized in that all the strain gauges are divided into at least four groups;
presetting a bending moment M1 measuring position which is away from the axis of the pedal hole (3) by Z1 along the length direction of the crank main body (1), arranging at least one first strain gauge (4) and at least one second strain gauge (5) at the bending moment M1 measuring position, wherein the first strain gauge (4) and the second strain gauge (5) are respectively attached to the outer side and the inner side of the crank main body (1) to form a first group of strain gauges, and the first group of strain gauges form a half-bridge or full-bridge circuit;
presetting a bending moment M2 measuring position with a Z2 distance between the length direction of the crank main body (1) and the axis of the pedal hole (3), arranging at least one third strain gauge (6) and at least one fourth strain gauge (7) at the bending moment M2 measuring position, wherein the third strain gauge (6) and the fourth strain gauge (7) are respectively attached to the outer side and the inner side of the crank main body (1) to form a second group of strain gauges, and the second group of strain gauges form a half-bridge or full-bridge circuit;
presetting a measuring position for measuring a bending moment M3 caused by a force Fx for driving the crank to rotate, and arranging at least one fifth strain gauge (8) and at least one sixth strain gauge (9) at the measuring position for the bending moment M3, wherein the fifth strain gauge (8) and the sixth strain gauge (9) are both attached to the inner side of the crank main body (1) to form a third group of strain gauges, and the third group of strain gauges form a half-bridge or full-bridge circuit;
the measuring device is characterized in that a measuring position for measuring the axial force Fz along the length direction of the crank main body (1) is preset, the measuring position of the axial force Fz is positioned between a bending moment M1 measuring position and a bending moment M2 measuring position, at least one seventh strain gage (10) and at least one eighth strain gage (11) are arranged at the measuring position of the axial force Fz, the seventh strain gage (10) and the eighth strain gage (11) are respectively attached to the outer side and the inner side of the crank main body (1) to form a fourth group of strain gages, and the fourth group of strain gages form a half bridge or a full bridge circuit.
2. The bicycle crank dynamometer for measuring force direction and position according to claim 1, wherein: the first strain gauge (4), the second strain gauge (5), the third strain gauge (6), the fourth strain gauge (7), the fifth strain gauge (8), the sixth strain gauge (9), the seventh strain gauge (10) and the eighth strain gauge (11) are all one.
3. The bicycle crank dynamometer for measuring force direction and position according to claim 2, wherein: on the inner side surface of the crank main body (1), the second strain gauge (5), the eighth strain gauge (11) and the fourth strain gauge (7) are sequentially arranged on a connecting line from the center of the bicycle axle center hole (2) to the center of the pedal hole (3) in a centered mode.
4. The bicycle crank dynamometer for measuring force direction and position according to claim 3, wherein: on the inner side surface of the crank main body (1), the fifth strain gauge (8) and the sixth strain gauge (9) are respectively positioned at two side directions of a connecting line of the center of the bicycle axle center hole (2) and the center of the pedal hole (3).
5. The bicycle crank dynamometer for measuring force direction and position according to claim 4, wherein: on the inner side surface of the crank body (1), the sixth strain gauge (9) and the fifth strain gauge (8) are respectively arranged at the left side and the right side of an eighth strain gauge (11).
6. The bicycle crank dynamometer for measuring force direction and position according to claim 3, wherein: on the outer side surface of the crank main body (1), the first strain gauge (4), the seventh strain gauge (10) and the third strain gauge (6) are sequentially and centrally arranged on a connecting line from the center of the bicycle axle center hole (2) to the center of the pedal hole (3).
7. The bicycle crank dynamometer of claim 6, wherein the crank dynamometer includes a position sensor for sensing a force applied to the bicycle crank dynamometer, and a power supply unit for supplying power to the bicycle crank dynamometer, the power supply unit including: the distance between the seventh strain gage (10) and the axis of the pedal shaft (12) is equal to the distance between the eighth strain gage (11) and the axis of the pedal shaft (12), and the seventh strain gage (10) is opposite to the eighth strain gage (11).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220531843.4U CN217716728U (en) | 2022-03-11 | 2022-03-11 | Bicycle crank power meter for measuring force-exerting direction and position |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220531843.4U CN217716728U (en) | 2022-03-11 | 2022-03-11 | Bicycle crank power meter for measuring force-exerting direction and position |
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| Publication Number | Publication Date |
|---|---|
| CN217716728U true CN217716728U (en) | 2022-11-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202220531843.4U Active CN217716728U (en) | 2022-03-11 | 2022-03-11 | Bicycle crank power meter for measuring force-exerting direction and position |
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| CN (1) | CN217716728U (en) |
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- 2022-03-11 CN CN202220531843.4U patent/CN217716728U/en active Active
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