JP4240397B2 - Inspection method of fuel pump - Google Patents

Description

  The present invention relates to a fuel pump inspection method using a brush motor.

A plurality of segments that are electrically connected to the coils wound around the armature are arranged in the rotational direction to form a commutator, and the brush sequentially contacts each segment as the armature rotates. A fuel pump using a brush motor that rectifies a drive current supplied to a child is known (see, for example, Patent Document 1).
And before operating the fuel pump in the test fluid and measuring the discharge amount of the fuel pump, etc., by measuring the rotational operation and rectification state of the fuel pump in the dry state, the coil breakage, the crack of the magnet, Inspections for detecting abnormalities in the fuel pump, such as steps on the straightening surfaces of the segments, are being conducted.
In such an abnormality inspection, the minimum operating voltage that guarantees the operation of the fuel pump when it is actually used is applied to the fuel pump, and the current waveform of the drive current that is rectified by the commutator and flows to the armature is inspected. It is known to do.

Japanese Patent Publication No. 7-85642

  By the way, in the brush motor, when the segment moves away from the brush as the armature rotates, a discharge may occur between the brush and the segment due to the release of electromagnetic energy accumulated in the coil. When a discharge occurs between the brush and the segment, the brush and the segment are subject to discharge wear, which may cause a poor electrical contact between the brush and the segment.

  Therefore, as shown in FIG. 13, the present applicant connects segments 300 adjacent to each other in the rotation direction with a capacitor 320, and when the brush 302 is separated from the segment 300, a high-frequency discharge current I passes through the capacitor 320 and is segmented. A configuration is considered in which 300 is bypassed and flows between adjacent coils 310. Thereby, even if the brush 302 is separated from the segment 300, no discharge is generated between the segment 300 and the brush 302, so that the discharge wear of the segment 300 and the brush 302 can be prevented.

However, if the capacitor 320 is used to prevent the discharge from occurring between the segment 300 and the brush 302, the surge current generated in the drive current flowing through the fuel pump becomes large, and the voltage applied to the fuel pump is the minimum operation. Even with a voltage, the waveform of the drive current varies as shown in FIG. In this waveform, it is difficult to identify whether the fluctuation of the waveform is caused by a fuel pump abnormality, surge current, or noise, and the accuracy of the fuel pump abnormality inspection is reduced.
SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel pump inspection method for accurately detecting abnormality of a fuel pump using a capacitor in order to prevent discharge from occurring between a brush and a segment.

  According to the first to fourth aspects of the present invention, since the armature is rotated by applying a voltage lower than the minimum operating voltage when the fuel pump is used, in order to prevent a discharge generated between the brush and the segment. The electromagnetic energy stored in the used capacitor is reduced. As a result, the surge current generated in the drive current flowing through the armature is reduced, and the waveform can be easily identified.

  However, if the armature is rotated by applying a voltage lower than the minimum operating voltage when the fuel pump is used, the rotational speed of the armature varies due to sliding resistance or magnetic resistance. As a result, since the length of one cycle of the drive current corresponding to each segment, the start point level, or the end point level varies, it is difficult to detect the abnormality of the fuel pump based on the waveform as it is.

  Therefore, according to the fuel pump inspection method according to claims 1 to 4, the drive current is shaped by matching the time width, start point level, and end point level of one cycle of the drive current corresponding to each segment. The disturbance of the waveform of the drive current due to the external factor caused by adding Therefore, the abnormality of the fuel pump can be detected with high accuracy based on the waveform of the shaped current obtained by shaping the drive current.

  By the way, for example, even when the average current value (effective value) is obtained for the shaping current having the number of cycles equal to the number of segments when the armature makes one rotation, and the comparison with the average current value of the normal reference current, It is averaged, and the abnormality may not appear in the average current value of the shaping current. Even if the amplitude difference of the shaping current is obtained and compared with the amplitude difference of the reference current, the amplitude difference is a difference between the maximum value and the minimum value of the amplitude. If there is an abnormality in the waveform of the shaping current, the abnormality cannot be detected.

Therefore, according to the second aspect of the present invention, the difference between the waveforms in one cycle becomes obvious by determining the area difference of the waveforms between the shaping currents of one cycle corresponding to each of the plurality of segments. Therefore, the abnormality of the fuel pump can be detected with high accuracy.
However, when the area difference of the waveform is determined between the shaping currents of one cycle corresponding to each segment as described above, the waveform of the shaping current may be greatly different even if the area difference is small. In this case, abnormality may not be detected by determining the area difference.

  Therefore, according to the third aspect of the present invention, the shaping currents corresponding to a plurality of segments constituting the commutator are compared, the maximum current obtained by connecting the maximum current values at the respective points on the time axis in one cycle, and the minimum current. By comparing the area difference of the current waveform with the minimum current connected with the value, an abnormality in the shaping current that does not appear due to the area difference between the shaping currents in one cycle can be detected.

  When the coil is star-connected as in the fourth aspect of the invention, if a capacitor is used to prevent discharge generated between the brush and the segment, the surge current generated in the drive current tends to increase. is there. However, in the invention described in claim 4, since the inspection is performed by applying the invention described in claims 1 to 3 and applying a voltage lower than the minimum operating voltage, the surge current generated in the drive current is reduced, and the high Abnormality of the fuel pump can be detected with high accuracy.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A fuel pump according to a first embodiment of the present invention is shown in FIGS. The fuel pump 10 is, for example, an in-tank pump that is mounted in a fuel tank such as a vehicle. The housing 12 is a common housing for the pump unit 14 and the motor unit 15. The housing 12 fixes the pump cover 16 and the end support cover 19 by caulking.

  The pump casing 18 is sandwiched between the pump cover 16 and the housing 12. A C-shaped pump flow path 24 is formed between the pump cover 16 and the pump casing 18. The pump cover 16 and the pump casing 18 are case members that rotatably accommodate an impeller 20 as a rotating member. The pump cover 16, the pump casing 18, and the impeller 20 constitute a pump unit. The pump casing 18 supports the bearing member 26 on the inner peripheral side.

  Many blade grooves are formed in the outer peripheral edge of the impeller 20 formed in a disk shape. When the impeller 20 rotates with the shaft 22 by the rotation of the armature 40, a pressure difference is generated by the fluid frictional force before and after the blade groove of the impeller 20, and the fuel in the pump passage 24 is added by repeating this with a large number of blade grooves. Pressed. The fuel in the fuel tank sucked into the pump flow path 24 from the fuel suction port 80 formed in the pump cover 16 by the rotation of the impeller 20 is discharged from the communication passage 82 of the pump casing 18 to the armature 40 side. Further, the fuel passes through a fuel passage 84 formed between the armature 40 and the permanent magnet 30, travels toward the commutator 70, passes through the fuel discharge port 86, and is discharged from the fuel pump 10 to the engine side.

As shown in FIG. 2, four permanent magnets 30 formed in a quarter arc shape are attached to the inner peripheral wall of the housing 12 on the circumference. The permanent magnet 30 has four magnetic poles having different poles in the rotation direction.
As shown in FIG. 1, a commutator 70 is assembled to the armature 40 on the side in the axial direction opposite to the impeller 20. A shaft 22 as a rotating shaft of the armature 40 is supported by bearing members 26 and 27 that are accommodated and supported in the pump casing 18 and the end support cover 19, respectively.

As shown in FIG. 2, the armature 40 has a central core 42 at the center of rotation. The shaft 22 is press-fitted into the central core 42. The central core 42 is formed in a cylindrical shape having a hexagonal cross section, and has a recess 44 extending in the direction of the rotation axis on each of the six outer peripheral walls. The width of the recess 44 becomes narrower toward the outer side in the radial direction.
The six magnetic cores 50 are installed on the outer periphery of the central core 42 in the rotational direction. A bobbin 60 is fitted in each magnetic pole core 50, and a coil 62 is formed by concentrating windings on the outer periphery of the bobbin 60. The inner peripheral side end of the magnetic pole core 50 is fitted in the recess 44 of the central core 42.

  As shown in FIG. 1, the end of each coil 62 on the commutator 70 side is electrically connected to the coil terminal 64. The coil terminal 64 is fitted and electrically connected to the commutator terminal 74 on the commutator 70 side. The end of the coil 62 opposite to the commutator 70 on the impeller 20 side is electrically connected to the coil terminal 66. The six coil terminals 66 are electrically connected by an annular terminal 68.

  The commutator 70 has six segments 72 installed in the rotational direction (see FIG. 3A). The segments 72 are made of, for example, carbon, and the segments 72 adjacent to each other in the rotation direction are electrically insulated by the air gap and the insulating resin material 76. As shown in FIG. 3A, among the six segments 72, the segments 72 facing each other in the radial direction are connected oppositely and electrically connected. Therefore, the coils 62 connected to the oppositely connected segments 72 are connected in parallel. Of the six segments 72, the four segments 72 adjacent in the rotation direction are connected to each other by three capacitors 78. As a result, when the two coils 62 connected in parallel and connected in parallel with the segment 72 are regarded as one coil 62, the coil 62 and the capacitor are as shown in FIG. Connected. In FIG. 3B, reference numeral 90 denotes a neutral point where the coil 62 is connected by the annular terminal 68. Specifically, the capacitor 78 is provided on the side of the commutator 70 on the side opposite to the commutation surface (the side opposite to the contact surface with the brush).

  By installing the capacitor 78 in this manner, as described in FIG. 13, when the brush 302 (not shown) is separated from the segment 72 (reference numeral 300 in FIG. 13), the high-frequency discharge current I is converted into the capacitor 78 (reference numeral in FIG. 13). 300) bypasses segment 72 and flows between adjacent coils 62 (reference numeral 310 in FIG. 13). Even if the brush 302 is separated from the segment 72, no discharge is generated between the segment 72 and the brush 302, so that the discharge wear of the segment 72 and the brush 302 can be prevented. Therefore, good electrical contact between the segment 72 and the brush 302 can be maintained. When the segment 72 and the brush 302 are in contact, the current from the coil 62 flows to the brush 302 via the segment 72.

Next, a fuel pump inspection method will be described.
Normally, the battery voltage when the fuel pump 10 is used is 12V. However, the operation of the fuel pump 10 is guaranteed up to a minimum operating voltage of 6V in consideration of a voltage drop due to battery discharge or the like. On the other hand, in the present embodiment, an inspection voltage of 1.5V ± 0.1V is applied to operate the fuel pump, and abnormality of the fuel pump 10 is detected according to the following steps. The abnormality inspection of the fuel pump 10 in the present embodiment is performed in the dry state before the fuel pump 10 is operated in the test fluid and the discharge amount of the fuel pump 10 is measured.

(1) Current detection step FIG. 4A shows a drive current that is rectified by the commutator 70 and flows to the armature 40 when the fuel pump 10 is operated by applying a test voltage of 1.5V ± 0.1V. This is a current waveform 100 in which is detected. The data of the current waveform 100 is obtained as digital data of current values sampled on the time axis.
When the current waveform 100 shown in FIG. 4A detected by applying a voltage lower than the minimum operating voltage is compared with the waveform of the drive current when the minimum operating voltage is applied as shown in FIG. At 100, periodic waveform changes clearly appear. However, since the noise is generated in the drive current as it is, the noise is removed by the digital filter to obtain the waveform 110 shown in FIG.

  By the way, when the fuel pump 10 is operated at a voltage lower than the lowest operating voltage that is normally used, the torque that rotates the armature 40 is small, and therefore the rotational speed of the armature 40 varies due to sliding resistance, magnetic resistance, and the like. Arise. As a result, as shown in FIG. 5, when the waveforms 111, 112, 113, 114, 115, 116 of one cycle corresponding to each segment 72 are compared, the time width (t1, t2, t3) of one cycle is compared. , T4, t5, t6) There is a difference in the start point level or end point level of one cycle.

(2) Shaping step With the waveform 110 as it is, it cannot be determined whether the difference in the waveform of the drive current is caused by the abnormality of the fuel pump 10 or the voltage is lowered. Therefore, as shown in FIG. 6, for example, the waveforms 111 and 112 having different time widths of one cycle corresponding to the cycle times of t1 and t2 are expanded or compressed in the time direction to have the same time width t0. Further, the shaping waveforms 121 and 122 are obtained by matching the starting point level and the ending point level of the drive current to the same value. In FIG. 6, in order to clarify the difference between the waveform 111 and the waveform 112, and the shaped waveform 121 and the shaped waveform 122, the waveform 111 and the shaped waveform 121 are represented by solid lines, and the waveform 112 and the shaped waveform 122 are represented by dotted lines.

The specific method of adjusting the starting point level and the ending point level of the driving current after adjusting the time width to t0 is as follows. First, the starting point of one cycle of the driving current corresponding to the segment 72 is translated in the current direction to change the starting point level. Match.
Next, as shown in FIG. 7, if the current level at time t from the start point in one cycle is I, and the level difference between the current level Is at the start point and the current level Ie at the end point is ΔI = Ie−Is. The current level at time t of the shaped waveform 121 after shaping is obtained as I−ΔI × (t / t0). Thus, the current level difference ΔI is proportionally distributed within one cycle, and the levels of the start point and the end point are matched. FIG. 8A shows six shaping currents in one cycle corresponding to each segment 72 obtained by matching the time width, the start point level, and the end point level in one cycle in this way.
Next, with respect to the six shaped waveforms shown in FIG. 8A, the maximum current 130 connected with the maximum value at the time lapse t in one cycle and the minimum connected with the minimum value at the time lapse t within one cycle. The current 132 is obtained.

(3) Abnormality detection step Then, the difference between the area of the envelope waveform of the maximum current 130 and the area of the envelope waveform of the minimum current 132 is obtained, and when the difference is equal to or smaller than a predetermined value, there is no abnormality, and when the difference is larger than the predetermined value It is determined that there is an abnormality. In the comparison of the waveforms of the maximum current 130 and the minimum current 132 shown in FIG. 8B, it is determined that there is no abnormality because the area difference is small.

  On the other hand, FIG. 9 shows a waveform 140 obtained by removing noise from the drive current detected from the abnormal fuel pump. As it is, since the time width of one cycle of the drive current, the start point level, and the end point level vary, it cannot be determined whether there is an abnormality. Therefore, as described above, the waveform shown in FIG. 10A is obtained by combining the time width of one cycle, the start point level, and the end point level.

  Next, the maximum current 150 connected with the maximum value in the time lapse t within one cycle and the minimum current 152 connected with the minimum value in the time lapse t within one cycle are obtained. The difference between the area of the envelope waveform of the maximum current 150 obtained in this way and the area of the envelope waveform of the minimum current 152 is larger than that in FIG. 8B and exceeds the predetermined range. It is determined that there is an abnormality.

  Here, as in the waveforms shown in FIG. 4B and FIG. 9, noise is removed, but before the time width of one cycle, the start point level and the end point level are matched, that is, the state of the drive current before shaping. Then, as shown in FIG. 11, there is almost no difference in the average value (effective value), maximum value, minimum value, and overall area of the drive current waveform during one rotation of the commutator, and the fuel pump is abnormal. It is difficult to determine whether it is normal or normal.

  However, the time width of one cycle, the start point level, and the end point level are combined, and the maximum current connecting the maximum value in the time lapse t in one cycle and the minimum current connecting the minimum value in the time lapse t in one cycle. There is a clear difference in the difference in the area of the waveform after shaping. Therefore, the fuel pump abnormality can be detected with high accuracy by comparing the area difference between the maximum current waveform and the minimum current waveform with a predetermined area difference.

(Second Embodiment)
A second embodiment of the present invention is shown in FIG. In the fuel pump for determining an abnormality in the second embodiment, the coil 200 is delta-connected, and as in the first embodiment, in order to prevent discharge from occurring between the segment and the brush, it is shown in FIG. A capacitor 202 is connected as described above.

  As described above, even when the coil 200 is delta-connected, the surge current component in the drive current is increased by using the capacitor 202 for preventing discharge. Therefore, as in the first embodiment, a fuel pump abnormality is detected by applying a voltage lower than the minimum operating voltage of the fuel pump to the fuel pump, shaping the drive current, and determining the area difference in the waveform of the shaped current. it can.

(Other embodiments)
In the first embodiment, the waveform of FIG. 8A is further processed to obtain the waveform of FIG. 8B, and then the area difference between the waveforms of the maximum current and the minimum current is obtained to detect an abnormality in the fuel pump. However, the abnormality of the fuel pump 10 may be detected by obtaining the area difference between the waveforms in the state of FIG.
In the first embodiment, the three capacitors 78 are provided so as to straddle the four segments 72 adjacent in the rotational direction. However, the number of capacitors 78 is not limited to this, and if at least one capacitor 78 is provided. Good.

It is sectional drawing which shows the fuel pump by 1st Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. (A) is a typical block diagram which shows the connection state of a segment, a coil, and a capacitor | condenser, (B) is a circuit diagram which shows the connection state of a capacitor | condenser and a coil. (A) is a raw waveform diagram of the detected drive current, and (B) is a waveform diagram obtained by removing noise from the detected drive current. It is an enlarged view which shows the waveform for 1 rotation of the commutator in (B) of FIG. (A) is a waveform diagram in which drive currents of one cycle corresponding to two segments are overlapped, and (B) is a waveform diagram showing a shaping current in which the time width, start point level, and end point level of the drive current are matched. It is. (A) is a wave form diagram which shows the shaping current which made time width of drive current correspond, (B) is a wave form diagram which shows the shaping current which made the start point level and end point level of drive current correspond. It is a wave form diagram which piled up shaping current corresponding to six segments, and (B) is a wave form diagram which connected a maximum value and a minimum value of six shaping currents of (A), respectively. It is a wave form diagram corresponding to Drawing 4 (B) of an abnormal fuel pump. FIG. 10B is a waveform diagram in which shaping currents corresponding to the drive currents shown in FIG. 9 are superimposed, and FIG. 10B is a waveform diagram in which the maximum values and the minimum values of the six shaping currents in FIG. It is a comparison figure which shows the test value of the fuel pump before and behind shaping of the waveform by the presence or absence of abnormality. It is a circuit diagram at the time of carrying out the delta connection of the coil by 2nd Embodiment of this invention. It is explanatory drawing which shows the circuit which used the capacitor | condenser in order to prevent that discharge generate | occur | produces between a brush and a segment. It is a wave form diagram which shows the drive current detected with the circuit of FIG.

Explanation of symbols

10 fuel pump, 14 pump section, 40 armature, 62 coil, 70 commutator, 72 segment, 78 condenser, 302 brush

Claims (4)

Permanent magnets that are installed on the circumference and alternately form a plurality of magnetic poles with different poles;
An armature that is rotatably installed on the inner peripheral side of the permanent magnet;
Rectification in which a plurality of segments electrically connected to the coil wound around the armature are arranged in the rotational direction and rotated together with the armature, and the segments adjacent in the rotational direction are electrically insulated from each other With the child,
A brush that sequentially contacts each segment by rotation of the armature;
It is electrically connected to a circuit including the commutator and the armature, bypasses electromagnetic energy emitted by the coil as the armature rotates, and discharge is generated between the brush and the segment. A capacitor to prevent,
A pump unit that is driven by the armature and pressurizes the fuel;
A method for inspecting a fuel pump comprising:
A current detection step of rotating the armature by applying a voltage lower than a minimum operating voltage when using the fuel pump, and detecting a drive current rectified by the commutator and flowing through the armature;
The driving current that flows corresponding to each segment during one rotation of the commutator is set to one cycle, and the driving current of one cycle corresponding to each segment is made to coincide with the time width, start point level, and end point level of the driving current. A shaping process for shaping
An abnormality detection step of detecting an abnormality of the fuel pump based on the shaping current shaped in the shaping step;
A method for inspecting a fuel pump, comprising:   2. The fuel pump abnormality according to claim 1, wherein in the abnormality detection step, the abnormality of the fuel pump is detected by comparing the area of the waveform between the shaping currents of one cycle respectively corresponding to the plurality of segments. Inspection method. In the shaping step, the shaping currents corresponding to the plurality of segments are compared, and a maximum current value obtained by connecting the maximum current values at each point on the time axis in one cycle and a minimum current value obtained by connecting the minimum current values are obtained. Seeking
2. The fuel pump inspection method according to claim 1, wherein in the abnormality detection step, an abnormality of the fuel pump is detected based on an area difference between the waveform of the maximum current and the waveform of the minimum current. The fuel coil inspection method according to claim 1, wherein the coil is star-connected.

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