JP2023131488A - vane pump - Google Patents

Abstract

To suppress the occurrence of cavitation.SOLUTION: A vane pump 100 includes: a rotor 2 to be rotationally driven; a plurality of vanes 3 provided so as to freely reciprocate in a radial direction with respect to the rotor 2; a cam ring 4 having an inner peripheral cam surface 4a with which a tip of the vane 3 is brought into sliding contact along with the rotation of the rotor 2; a pump chamber 6 defined by the rotor 2, the cam ring 4, and the pair of adjacent vanes 3; a side plate 10 .provided in contact with one side face of the cam ring 4; a suction port 11 formed in the side plate 10 to guide operating fluid to the pump chamber 6; and groove parts 20, 30, 40 formed in the inner peripheral cam surface 4a of the scam ring 4 while lying on a starting end 11a of the suction port 11 in a rotating direction of the rotor 2.SELECTED DRAWING: Figure 3A

Description

The present invention relates to a vane pump.

In the vane pump disclosed in Patent Document 1, a notch is formed in the side plate from the opening edge of the suction port in a direction opposite to the rotational direction of the rotor.

JP 2021-188539 Publication

In a vane pump in which a notch is formed in the suction port as described in Patent Document 1, high-pressure oil in the pump chamber is guided to the suction port through the notch before communicating with the suction port. It has the effect of alleviating pressure fluctuations when communicating.

However, since the notch is formed in the side plate, when the high-pressure oil in the pump chamber is guided to the suction port through the notch, a flow of hydraulic oil occurs along the side plate. This flow pulls the oil near the center of the pump chamber, lowering the pressure near the center of the pump chamber and potentially causing cavitation. As described above, in the vane pump described in Patent Document 1, there is room for improvement regarding the occurrence of cavitation.

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the occurrence of cavitation.

The present invention relates to a vane pump that includes a rotor that is rotationally driven, a plurality of vanes that are provided to be able to reciprocate in the radial direction with respect to the rotor, and an inner periphery on which the tip of the vane slides as the rotor rotates. a cam ring having a cam surface; a pump chamber partitioned by the rotor, the cam ring, and a pair of adjacent vanes; a side member provided in contact with one side of the cam ring; It is characterized by comprising a suction port for introducing fluid, and a groove formed on the inner circumferential cam surface of the cam ring so as to extend over the starting end of the suction port in the rotational direction of the rotor.

In this invention, when the pump chamber communicates with the groove, the high-pressure fluid in the pump chamber is guided to the suction port through the groove formed on the inner cam surface of the cam ring. A fluid flow occurs. Therefore, since the pressure drop in the pump chamber is suppressed, the occurrence of cavitation can be suppressed.

Further, the present invention is characterized in that the groove portion is formed in the center portion of the cam ring in the thickness direction.

In this invention, since the working fluid guided through the groove passes near the center in the thickness direction of the pump chamber, a local pressure drop near the center of the pump chamber is more effectively suppressed.

Further, the present invention is characterized in that the groove portion is formed in a rectangular shape along the rotation direction of the rotor when viewed from the rotation center of the rotor, and is formed in an arch shape in a cross section perpendicular to the axial direction of the cam ring.

In this invention, even when the rotor is rotating at high speed, it is possible to suppress a local pressure drop near the center of the pump chamber.

Further, the present invention is characterized in that the groove is formed in a diamond shape along the rotational direction of the rotor when viewed from the rotation center of the rotor, and is formed in a triangular shape in a cross section perpendicular to the axial direction of the cam ring.

According to the present invention, even when the rotor rotates at low speed, pressure fluctuations in the pump chamber can be made gentle, and local pressure drops near the center of the pump chamber can be suppressed.

Further, the present invention is characterized in that the groove portion is formed in a circular shape when viewed from the rotation center of the rotor, and is formed in a semicircular shape in a cross section perpendicular to the axial direction of the cam ring.

In this invention, a local pressure drop near the center of the pump chamber can be suppressed at low cost.

According to the present invention, the occurrence of cavitation can be suppressed.

FIG. 1 is a sectional view of a vane pump according to an embodiment of the present invention. FIG. 2 is a plan view of a rotor, a cam ring, and a side plate of a vane pump according to an embodiment of the present invention. It is a figure of the inner peripheral cam surface of the cam ring of the vane pump concerning an embodiment of the present invention. FIG. 3A is a cross-sectional view taken along line AA in FIG. 3A. FIG. 3A is a diagram of an inner cam surface of a cam ring of a vane pump according to a comparative example, and is shown corresponding to FIG. 3A. It is a figure of the inner peripheral cam surface of the cam ring of the vane pump concerning modification 1 of an embodiment of the present invention. 5A is a sectional view taken along line BB in FIG. 5A. FIG. It is a figure of the inner peripheral cam surface of the cam ring of the vane pump concerning modification 2 of an embodiment of the present invention. 6A is a sectional view taken along line CC in FIG. 6A. FIG.

Embodiments of the present invention will be described below with reference to the drawings.

A vane pump 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The vane pump 100 is used as a fluid pressure supply source for fluid pressure equipment mounted on a vehicle or industrial machine, such as a power steering device or a continuously variable transmission. In this embodiment, a fixed capacity vane pump 100 using hydraulic oil as the working fluid will be described. Note that the vane pump 100 may be a variable displacement vane pump.

In the vane pump 100, power from a drive source (not shown) such as an engine or an electric motor is transmitted to an end of a drive shaft 1, and a rotor 2 connected to the drive shaft 1 rotates. The rotor 2 rotates clockwise in FIG.

The vane pump 100 includes a plurality of vanes 3 that are provided to be able to reciprocate in the radial direction with respect to the rotor 2, and an inner circumferential cam surface that accommodates the rotor 2 and that the tips of the vanes 3 slide into contact with as the rotor 2 rotates. 4a, and a housing 5 that accommodates the rotor 2 and the cam ring 4. A plurality of pump chambers 6 are defined by the rotor 2, the cam ring 4, and a pair of adjacent vanes 3.

The rotor 2 is an annular member and is connected to the tip of the drive shaft 1 by a spline connection. The rotor 2 has radially formed slits 2a that open on the outer peripheral surface, and the vanes 3 are slidably inserted into the slits 2a.

The cam ring 4 is an annular member with an inner cam surface 4a having a substantially elliptical shape. The cam ring 4 has two suction regions that expand the volume of the pump chamber 6 as the rotor 2 rotates, and two discharge regions that contract the volume of the pump chamber 6 as the rotor 2 rotates. That is, during one rotation of the rotor 2, the vane 3 reciprocates twice and the pump chamber 6 repeats expansion and contraction twice. The suction region and the discharge region are defined by the shape of the inner circumferential cam surface 4a.

A side plate 10 is provided in contact with one side of the cam ring 4. The side plate 10 is a disc-shaped member.

The rotor 2, cam ring 4, and side plate 10 are housed in a pump housing portion 5a formed in a concave shape in the housing 5. The pump housing portion 5a is sealed by a pump cover 7. The pump cover 7 is provided in contact with the other side of the cam ring 4. The side plate 10 and the pump cover 7 are arranged to sandwich both side surfaces of the rotor 2 and the cam ring 4, and seal the pump chamber 6. The side plate 10 and the pump cover 7 function as a side member provided in contact with one side of the cam ring 4.

A high pressure chamber 16 into which hydraulic oil discharged from the pump chamber 6 is guided is formed in the bottom surface 5b of the pump accommodating portion 5a in an annular shape. The high pressure chamber 16 is partitioned by a side plate 10 arranged on the bottom surface 5b. The high pressure chamber 16 communicates with a discharge passage (not shown) that is opened and formed on the outer surface of the housing 5 .

The sliding surface 7a of the pump cover 7 on which the rotor 2 slides has two suction ports 8 (see FIG. 3A) that guide hydraulic oil to the pump chamber 6 and two discharge ports that discharge the hydraulic oil from the pump chamber 6. 9 is formed. The suction port 8 is formed corresponding to the two suction regions of the cam ring 4. The discharge port 9 is formed corresponding to the discharge area of the cam ring 4. Further, the pump cover 7 is formed with a suction passage (not shown) that guides the hydraulic oil in the tank to the pump chamber 6 through the suction port 8 .

As shown in FIG. 2, the side plate 10 is formed with two suction ports 11 that guide hydraulic oil to the pump chamber 6 and two discharge ports 12 that discharge the hydraulic oil from the pump chamber 6. The suction port 11 is formed in a groove shape on the sliding surface 10a of the side plate 10 on which the rotor 2 slides, corresponding to the two suction regions of the cam ring 4. The suction port 11 communicates with the suction port 8 of the pump cover 7 through a passage (not shown) formed in the inner peripheral surface of the pump housing portion 5a. Therefore, the hydraulic oil from the suction passage is guided to the pump chamber 6 through the suction port 8 of the pump cover 7 and the suction port 11 of the side plate 10. The discharge port 12 is formed so as to correspond to the discharge area of the cam ring 4 and penetrate the side plate 10 in an arc shape. The discharge port 12 discharges the hydraulic oil from the pump chamber 6 to the high pressure chamber 16 .

Relative rotation of the cam ring 4, side plate 10, and pump cover 7 is restricted by two positioning pins (not shown). Thereby, the suction port 8 and the discharge port 9 of the pump cover 7 are positioned with respect to the suction area and the discharge area of the cam ring 4, and the suction port 11 and the discharge port 12 of the side plate 10 are positioned.

When the drive shaft 1 rotates due to the drive of the power source, the rotor 2 connected to the drive shaft 1 rotates, and each pump chamber 6 in the cam ring 4 is connected to the suction port 8 of the pump cover 7 and the side plate 10. Hydraulic oil is sucked in through the suction port 11, and is discharged into the high pressure chamber 16 through the discharge port 9 of the pump cover 7 and the discharge port 12 of the side plate 10. The hydraulic oil in the high pressure chamber 16 is supplied to the fluid pressure equipment through the discharge passage. In this way, each pump chamber 6 within the cam ring 4 supplies and discharges hydraulic oil by expanding and contracting as the rotor 2 rotates.

Two grooves 20 are formed in the inner cam surface 4a of the cam ring 4 in correspondence with the suction ports 8 and 11. Below, the groove portion 20 will be explained mainly with reference to FIG. 3. FIG. 3A is a diagram of the inner cam surface 4a of the cam ring 4 viewed from the rotation center of the rotor 2, and shows a cross section of the pump cover 7 and the side plate 10 along the inner cam surface 4a. FIG. 3B is a cross-sectional view taken along line AA in FIG. 3A. FIG. 3A shows adjacent pump chambers 6A and 6B separated by vanes 3, and the pump chambers 6A and 6B move from the left side to the right side. That is, the pump chamber 6A is on the rear side in the rotation direction, and the pump chamber 6B is on the front side in the rotation direction. FIG. 3A shows a state in which the pump chamber 6A communicates with the groove portion 20 but before communicating with the suction ports 8 and 11.

The groove portion 20 is formed in a concave shape on the surface of the inner circumferential cam surface 4a. The groove portion 20 is formed along the rotational direction of the rotor 2, and a portion thereof is formed over the starting end portions 8a, 11a of the suction ports 8, 11 in the rotational direction of the rotor 2. The starting ends 8a, 11a of the suction ports 8, 11 are the ends of the suction ports 8, 11 on the communication start side where the pump chamber 6 starts to communicate with each other as the rotor 2 rotates. In this manner, the groove portion 20 is formed so as to straddle the starting end of the suction port section in which the suction ports 8 and 11 are formed in the rotational direction of the rotor 2 . Further, the groove portion 20 is formed approximately at the center of the cam ring 4 in the thickness direction (vertical direction in FIG. 3A). The length of the cam ring 4 in the circumferential direction (in the left-right direction in FIG. 3A) in the groove portion 20 is longer than the thickness of the vane 3, and is formed to a length that communicates only the adjacent pump chambers 6.

The groove portion 20 has a function of alleviating pressure fluctuations in the pump chamber 6 and preventing cavitation from occurring when the pump chamber 6 transitions from the discharge region to the suction region. Specifically, when the pump chamber 6A communicates with the groove 20 before communicating with the suction ports 8 and 11 in the process of transitioning from the discharge area to the suction area (the state shown in FIG. 3A), the high pressure oil in the pump chamber 6A The pump chamber 6A is guided to the pump chamber 6B through the groove 20 and flows to the suction ports 8, 11 (reverse flow), so that the pump chamber 6A communicates with the suction ports 8, 11 in a state where the pressure is reduced. Therefore, pressure fluctuations when the pump chamber 6A communicates with the suction ports 8 and 11 are alleviated.

Here, a comparative example will be described with reference to FIG. 4. FIG. 4 is a diagram showing a comparative example and corresponds to FIG. 3A. In the comparative example, the groove 20 is not formed on the inner cam surface 4a of the cam ring 4, and instead, the starting end of the suction port 11 is formed on each of the sliding surface 10a of the side plate 10 and the sliding surface 7a of the pump cover 7. 11a and the starting end 8a of the suction port 8, a notch 50 is formed in a direction opposite to the rotational direction of the rotor 2. The notch 50 is formed in a groove shape so that the opening area gradually increases in the direction of rotation of the rotor 2. FIG. 4 shows a state in which the pump chamber 6A communicates with the notch 50, but before communicating with the suction ports 8 and 11.

The notch 50 has the same function as the groove 20 in that it alleviates pressure fluctuations when the pump chamber 6 communicates with the suction ports 8 and 11. However, since the notch 50 is formed in the pump cover 7 and the side plate 10, if the pump chamber 6A communicates with the notch 50 before communicating with the suction ports 8 and 11 (the state shown in FIG. 4), the pump chamber 6A The high-pressure oil flows along the sliding surface 7a of the pump cover 7 and the sliding surface 10a of the side plate 10, and flows into the suction port 8 and the suction port 11 through the notch 50 (flows backward). In this way, when the pump chamber 6A communicates with the notch 50, hydraulic oil flows along the sliding surface 7a of the pump cover 7 and the sliding surface 10a of the side plate 10. This flow may pull the hydraulic oil near the center of the pump chamber 6A, and the pressure near the center of the pump chamber 6A may locally decrease to negative pressure. This may cause cavitation to occur near the center of the pump chamber 6A. In addition, since the flow rate of the hydraulic oil flowing back from the pump chamber 6A to the suction port 8 and suction port 11 through the notch 50 is fast, noise may be generated due to the hydraulic oil colliding with the walls of the suction port 8 and suction port 11. There is.

In contrast, in the present embodiment, when the pump chamber 6A communicates with the groove 20 before communicating with the suction ports 8 and 11 (the state shown in FIG. 3A), the high pressure oil in the pump chamber 6A is transferred to the cam ring 4. It is guided to the pump chamber 6B through the groove 20 formed on the inner circumferential cam surface 4a and flows to the suction ports 8 and 11. Therefore, since the hydraulic oil flows along the inner circumferential cam surface 4a of the cam ring 4, a local pressure drop near the center of the pump chamber 6A is suppressed, and the occurrence of cavitation is suppressed. In particular, since the groove portion 20 is formed approximately at the center of the cam ring 4 in the thickness direction, the hydraulic oil guided through the groove portion 20 passes near the center of the pump chamber 6A in the thickness direction. pressure drop is more effectively suppressed. Note that the groove portion 20 does not need to be formed at the center portion of the cam ring 4 in the thickness direction, and may be formed offset from the center portion of the cam ring 4 in the thickness direction in the vertical direction in FIG. 3A. Even in that case, since the hydraulic oil flows along the inner circumferential cam surface 4a of the cam ring 4, there is a certain effect of suppressing the local pressure drop near the center of the pump chamber 6A.

Further, the high pressure oil in the pump chamber 6A is guided to the vicinity of the center of the pump chamber 6B through a groove 20 formed in the inner cam surface 4a of the cam ring 4, and then flows into the suction ports 8 and 11. In this way, the high-pressure oil in the pump chamber 6A does not directly flow into the suction ports 8 and 11, but passes through the center of the pump chamber 6B, so the force with which the hydraulic oil collides with the wall of the suction port 11 is reduced. , noise generation is suppressed. Further, by adjusting the shape of the groove portion 20, the wall surface position of the suction port 11 that the hydraulic oil collides with can be adjusted, so that the generation of noise can be further suppressed.

In this embodiment, as shown in FIG. 3A, the groove 20 is formed in a rectangular shape along the rotation direction of the rotor 2 when viewed from the rotation center of the rotor 2, and as shown in FIG. In a cross section perpendicular to the direction, it is formed in an arch shape (cylindrical shape). The groove portion 20 is formed so that the cross-sectional area of the flow path is substantially constant in the rotational direction of the rotor 2 . Therefore, immediately after the pump chamber 6A communicates with the groove 20, high-pressure oil is guided to the pump chamber 6B through the groove 20 at once. Therefore, even when the rotor 2 is rotating at high speed, a local pressure drop near the center of the pump chamber 6A can be suppressed.

The shape of the groove 20 shown in FIGS. 3A and 3B is an example, and the depth of the groove, the length in the rotational direction of the rotor 2, the curvature, the formation position on the inner cam surface 4a, etc. may vary depending on the specifications of the vane pump 100. By adjusting , the flow rate, flow velocity, and flow direction of the hydraulic oil through the groove are set. Thereby, depending on the specifications of the vane pump 100, it is possible to suppress a local pressure drop near the center of the pump chamber 6A, and to suppress the generation of noise due to the hydraulic oil colliding with the wall surface of the suction port 11. be able to.

According to the above embodiment, the following effects are achieved.

When the pump chamber 6 communicates with the groove 20, the high-pressure oil in the pump chamber 6 is guided to the suction ports 8 and 11 through the groove 20 formed on the inner cam surface 4a of the cam ring 4, so that the inner circumference of the cam ring 4 A flow of hydraulic oil occurs along the cam surface 4a. Therefore, since the pressure drop in the pump chamber 6 is suppressed, the occurrence of cavitation can be suppressed.

Modifications of this embodiment will be described below.

(1) Modification 1 will be described with reference to FIGS. 5A and 5B. 5A and 5B are diagrams showing a groove portion 30 according to modification example 1, and correspond to FIGS. 3A and 3B, respectively. In this modification, the shape of the groove 30 is formed into a diamond shape along the rotational direction of the rotor 2 when viewed from the rotation center of the rotor 2, as shown in FIG. It is triangular in cross section perpendicular to the direction. The groove portion 30 is formed such that the flow passage cross-sectional area gradually increases from the end toward the rotation direction of the rotor 2 . Therefore, when the pump chamber 6A communicates with the groove 30, high pressure oil is gradually guided through the groove 30 to the pump chamber 6B. Therefore, even when the rotor 2 is rotating at a low speed, pressure fluctuations in the pump chamber 6A can be made gentler, and a local pressure drop in the vicinity of the center of the pump chamber 6A can be suppressed.

(2) Modification 2 will be described with reference to FIGS. 6A and 6B. 6A and 6B are diagrams showing a groove portion 40 according to modification 2, and correspond to FIGS. 3A and 3B, respectively. In this modification, the shape of the groove portion 40 is circular when viewed from the rotation center of the rotor 2, as shown in FIG. 6A, and in a cross section perpendicular to the axial direction of the cam ring 4, as shown in FIG. 6B. formed into a circle. The diameter (left-right direction in FIG. 3A), which is the circumferential length of the cam ring 4 in the groove portion 40, is longer than the thickness of the vane 3. The groove portion 40 can be processed at a lower cost than the groove portions 20 and 30. When the pressure difference between the pump chamber 6 and the suction ports 8 and 11 is small, and the flow rate of hydraulic oil guided through the groove is small, the shape of the groove 40 according to this modification is limited to a local area near the center of the pump chamber 6A. This is effective because it can suppress the pressure drop at low cost.

(3) The suction port may be formed only in either the side plate 10 or the pump cover 7 as a side member.

(4) A second side plate may be arranged between the pump cover 7 and the cam ring 4 as a side member provided in contact with one side of the cam ring 4. That is, the pump chamber 6 may be partitioned by two side plates (side members) with the rotor 2 and the cam ring 4 interposed therebetween. In this form, a discharge port and a suction port are formed on the sliding surface of the second side plate on which the rotor 2 slides.

Hereinafter, the configuration, operation, and effects of the embodiments of the present invention will be collectively described.

The vane pump 100 includes a rotor 2 that is rotationally driven, a plurality of vanes 3 that are provided to be able to reciprocate in the radial direction with respect to the rotor 2, and an inner periphery on which the tips of the vanes 3 come into sliding contact as the rotor 2 rotates. A cam ring 4 having a cam surface 4a, a pump chamber 6 partitioned by the rotor 2, the cam ring 4, and a pair of adjacent vanes 3, and a side plate 10 (side member) provided in contact with one side of the cam ring 4. A suction port 11 is formed on the side plate 10 and guides the working fluid to the pump chamber 6, and a suction port 11 is formed on the inner peripheral cam surface 4a of the cam ring 4 so as to extend over the starting end 11a of the suction port 11 in the rotational direction of the rotor 2. groove portions 20, 30, and 40.

In this configuration, when the pump chamber 6 communicates with the grooves 20, 30, 40, the high pressure oil in the pump chamber 6 passes through the grooves 20, 30, 40 formed on the inner cam surface 4a of the cam ring 4 to the suction port 11. As a result, the hydraulic oil flows along the inner circumferential cam surface 4a of the cam ring 4. Therefore, since the pressure drop in the pump chamber 6 is suppressed, the occurrence of cavitation can be suppressed.

Furthermore, the grooves 20, 30, and 40 are formed at the center of the cam ring 4 in the thickness direction.

In this configuration, since the hydraulic oil guided through the grooves 20, 30, and 40 passes near the center of the pump chamber 6 in the thickness direction, a local pressure drop near the center of the pump chamber 6 is more effectively suppressed.

Further, the groove portion 20 is formed in a rectangular shape along the rotation direction of the rotor 2 when viewed from the rotation center of the rotor 2, and is formed in an arch shape in a cross section perpendicular to the axial direction of the cam ring 4.

With this configuration, even when the rotor 2 is rotating at a high speed, a local pressure drop near the center of the pump chamber 6 can be suppressed.

Further, the groove portion 30 is formed in a diamond shape along the rotational direction of the rotor 2 when viewed from the rotation center of the rotor 2, and is formed in a triangular shape in a cross section perpendicular to the axial direction of the cam ring 4.

With this configuration, even when the rotor 2 is rotating at low speed, pressure fluctuations in the pump chamber 6 can be made gentle, and a local pressure drop in the vicinity of the center of the pump chamber 6 can be suppressed.

Further, the groove portion 40 is formed in a circular shape when viewed from the rotation center of the rotor 2, and is formed in a semicircular shape in a cross section perpendicular to the axial direction of the cam ring 4.

With this configuration, a local pressure drop near the center of the pump chamber 6 can be suppressed at low cost.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. do not have.

100... Vane pump, 2... Rotor, 3... Vane, 4... Cam ring, 6, 6A, 6B... Pump chamber, 7... Pump cover (side member), 8... Suction port, 8a... Starting end, 10... Side plate (side member), 11... Suction port, 11a... Starting end, 20, 30, 40... Groove

Claims (5)

a rotor that is rotationally driven;
a plurality of vanes provided to be able to reciprocate in a radial direction with respect to the rotor;
a cam ring having an inner circumferential cam surface with which the tip of the vane slides in contact as the rotor rotates;
a pump chamber partitioned by the rotor, the cam ring, and a pair of adjacent vanes;
a side member provided in contact with one side of the cam ring;
a suction port formed in the side member and introducing working fluid into the pump chamber;
a groove formed on the inner circumferential cam surface of the cam ring and extending over a starting end of the suction port in the rotational direction of the rotor;
A vane pump characterized by comprising: The vane pump according to claim 1,
The vane pump is characterized in that the groove portion is formed in a central portion of the cam ring in the thickness direction. The vane pump according to claim 1 or 2,
The vane pump is characterized in that the groove portion is formed in a rectangular shape along the rotation direction of the rotor when viewed from the rotation center of the rotor, and is formed in an arch shape in a cross section perpendicular to the axial direction of the cam ring. The vane pump according to claim 1 or 2,
The vane pump is characterized in that the groove portion is formed in a diamond shape along the rotation direction of the rotor when viewed from the rotation center of the rotor, and is formed in a triangular shape in a cross section perpendicular to the axial direction of the cam ring. The vane pump according to claim 1 or 2,
The vane pump is characterized in that the groove portion is formed in a circular shape when viewed from the rotation center of the rotor, and is formed in a semicircular shape in a cross section perpendicular to the axial direction of the cam ring.

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