JP6691402B2 - Oil pump - Google Patents

Description

  The present invention relates to an oil pump driven by an engine.

  Conventionally, an oil pump mounted on a vehicle is driven by an engine to supply oil to a transmission and the like. However, the minimum discharge amount (flow rate) of the oil pump must be greater than or equal to the required flow rate required for the transmission or the like. Therefore, there is a problem that the oil pump discharges oil at a flow rate higher than a required flow rate when the load is low and the loss becomes large.

  Therefore, in Patent Document 1, the flow rate of oil is changed by a variable displacement oil pump to prevent the flow rate from significantly increasing beyond the required flow rate.

JP, 2003-201976, A

  However, since the variable displacement pump has a structure in which the volume of the pump chamber is changed, cavitation does not occur in the case of the volume that is the optimum pump chamber shape for the oil pump, but the pump chamber has the optimum shape. Cavitation may occur when the volume does not exist.

  Therefore, it is an object of the present invention to propose an oil pump capable of preventing an increase in the oil flow rate according to the engine speed while suppressing cavitation.

In order to solve the above problems, the oil pump of the present invention, pump up the oil from the suction passage, a rotating body for discharging the oil in the discharge flow path, a first shaft rotating said integrally with the rotating body, disposed on the first shaft coaxially, a second shaft that is rotated by the engine, is disposed between the first shaft and said second shaft, said second shaft and said first shaft by a frictional force A friction member for transmitting torque between the second shaft, an urging portion for urging the second shaft toward the first shaft to the extent that torque can be transmitted at the time of engine startup , and the hydraulic pressure in the discharge passage for the first member. A pressing portion that presses one shaft against the second shaft.

Moreover, the friction member, when the maximum torque transfer more torque transmitted to the first shaft from said second shaft is transmitted from said second shaft, sliding between the first shaft and the second shaft it may transmit the maximum torque transfer to the first shaft Te.

  According to the present invention, while suppressing cavitation, it is possible to prevent the flow rate of oil from increasing in accordance with the engine speed.

It is a schematic diagram showing the composition of an oil pump. It is a figure which shows the rotation speed of an engine, and the relationship of a flow volume. FIG. 6 is a diagram showing a relationship between the engine speed and torque when the hydraulic pressure in the discharge passage is constant. FIG. 6 is a diagram illustrating a change in torque when it is assumed that the engine speed is constant.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the invention unless otherwise specified. In this specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to omit redundant description, and elements not directly related to the present invention are omitted. To do.

  FIG. 1 is a schematic diagram showing the configuration of the oil pump 1. However, in the following, configurations and processes related to this embodiment will be described in detail, and descriptions of configurations and processes unrelated to this embodiment will be omitted. In FIG. 1, the flow of oil is indicated by a white arrow.

  As shown in FIG. 1, the oil pump 1 is a so-called internal gear pump, and includes a body 10, a cover 12, a rotating body 14, a first shaft 16, a second shaft 18, a bearing 20, a friction member 22, and a biasing member. The unit 24 and the pressing unit 26 are included.

  The oil pump 1 is fastened to the casing 28 by a fastening member (not shown) in a state where the rotating body 14, the first shaft 16, and the bearing 20 are housed inside the body 10 and the cover 12.

  A shaft hole 10a through which the first shaft 16 is inserted is formed in the body 10, and a shaft hole 12a through which the first shaft 16 is inserted is formed in the cover 12. The first shaft 16 is rotatably supported in the shaft hole 10a and the shaft hole 12a via a bearing 20.

  Further, the body 10 is formed with a housing hole 10b in a side surface facing the cover 12 so as to communicate with the shaft hole 10a, and the rotating body 14 is housed in the housing hole 10b.

  The rotating body 14 includes an inner rotor 14a and an outer rotor 14b. The inner rotor 14a is provided with a plurality of outer teeth on the outer peripheral surface thereof, is supported by the first shaft 16 at the center, and rotates integrally with the first shaft 16. The outer rotor 14b is provided with a plurality of inner teeth on its inner peripheral surface and is arranged on the outer peripheral side of the inner rotor 14a.

  The outer teeth of the inner rotor 14a have one less tooth than the inner teeth of the outer rotor 14b, and the inner rotor 14a and the outer rotor 14b are eccentrically meshed with each other. A plurality of spaces formed by the inner rotor 14a and the outer rotor 14b is a pump chamber 30, and when the inner rotor 14a rotates, the outer rotor 14b also rotates integrally. At this time, the plurality of pump chambers 30 sequentially repeats reduction and enlargement.

  The body 10 is opened at a position facing a range in which the volume of the pump chamber 30 is enlarged with the rotation of the rotating body 14 in the accommodation hole 10b, and is also opened toward the cover 12 side on the outer peripheral side of the accommodation hole 10b. The suction channel 10c is formed.

  In addition, the body 10 is opened at a position facing a range in which the volume of the pump chamber 30 is reduced in accordance with the rotation of the rotating body 14 in the accommodation hole 10b, and is provided on the outer peripheral side of the accommodation hole 10b and on the cover 12 side. A discharge flow path 10d having an opening is formed.

  The cover 12 is formed so as to penetrate in the axial direction of the first shaft 16, one of which is opened to the casing 28 side, and the other of which has a volume of the pump chamber 30 accompanying the rotation of the rotating body 14 in the accommodation hole 10b. A suction passage 12b is formed which is open at a position facing the expanding range and on the outer peripheral side of the accommodation hole 10b of the body 10. The portion of the suction passage 12b that is open to the outer peripheral side of the accommodation hole 10b of the body 10 is in communication with the suction passage 10c of the body 10.

  Further, the cover 12 is formed so as to penetrate in the axial direction of the first shaft 16, one of which is open to the casing 28 side, and the other of which is the pump chamber 30 along with the rotation of the rotating body 14 in the accommodation hole 10b. A discharge passage 12c is formed so as to open at a position facing the range where the volume is reduced and on the outer peripheral side of the accommodation hole 10b of the body 10. The portion of the discharge passage 12c that is open to the outer peripheral side of the housing hole 10b of the body 10 is in communication with the discharge passage 10d of the body 10.

  The casing 28 extends to the upper side in the vertical direction of the oil pan 32, and the strainer 34 is fixed to the bottom so that the tip of the strainer 34 is immersed in the oil stored in the oil pan 32. Further, the casing 28 is formed with an intake passage 28a so as to communicate with the intake passage 12b of the cover 12 from the strainer 34.

  Further, the casing 28 is formed with a discharge flow path 28b having one end communicating with the discharge flow path 12c of the cover 12.

  In the oil pump 1 configured in this way, the suction flow passage 28a of the casing 28, the suction flow passage 12b of the cover 12, and the suction flow passage 10c of the body 10 communicate with each other. Further, in the oil pump 1, the discharge flow passage 10d of the body 10, the discharge flow passage 12c of the cover 12, and the discharge flow passage 28b of the casing 28 communicate with each other.

  A valve 42 capable of adjusting the hydraulic pressure (flow rate) in the discharge flow channel 28b (discharge flow channel 38) is provided downstream of the discharge flow channel 28b, and the discharge flow rate is controlled based on the control of a TCU (Torque Control Unit). The hydraulic pressure (flow rate) of the passage 28b (discharge passage 38) is adjusted.

  In the following, the suction flow passage 28a of the casing 28, the suction flow passage 10c of the body 10, and the suction flow passage 12b of the cover 12 are collectively referred to simply as the suction flow passage 36. Further, the discharge flow passage 10d of the body 10, the discharge flow passage 12c of the cover 12, and the discharge flow passage 28b of the casing 28 are collectively referred to as a discharge flow passage 38.

  Therefore, the oil pump 1 guides the oil stored in the oil pan 32 to the pump chamber 30 via the strainer 34 and the suction passage 36 by the negative pressure action of the rotating body 14 as the rotating body 14 rotates. . Then, the oil guided to the pump chamber 30 is discharged from the pump chamber 30 to the discharge flow path 38 by the compression action due to the rotation of the rotating body 14, and is supplied to each part of the transmission.

  In this way, the oil pump 1 can supply the oil stored in the oil pan 32 to each part of the transmission.

  The second shaft 18 is arranged coaxially with the first shaft 16, and the friction member 22 is arranged between the first shaft 16 and the second shaft 18. The second shaft 18 is connected to the crankshaft of the engine via the torque converter and the drive chain, and rotates in proportion to (proportional to) the engine speed.

  When the first shaft 16 and the second shaft 18 are relatively close to each other, the friction member 22 transmits torque (transmission torque) from the second shaft 18 to the first shaft 16 by frictional force. Further, the maximum torque (maximum transmission torque) that can be transmitted from the second shaft 18 to the first shaft 16 changes due to the pressing force of the pressing portion 26 described in detail below, and a torque equal to or greater than the maximum transmission torque is output from the second shaft 18. When transmitted, the friction member 22 slides between the first shaft 16 and the second shaft 18, and transmits the maximum transmitted torque from the second shaft 18 to the first shaft 16.

  That is, the friction member 22 does not slip between the first shaft 16 and the second shaft 18 until the torque transmitted from the second shaft 18 reaches the maximum transmission torque, and All are transmitted to the first shaft 16. When the torque transmitted from the second shaft 18 becomes greater than the maximum transmission torque, the friction member 22 slides between the first shaft 16 and the second shaft 18 and transmits the maximum transmission torque to the first shaft 16. .

  The second shaft 18 is constantly biased toward the first shaft 16 by the biasing portion 24. The urging portion 24 is composed of, for example, a spring, and as will be described later in detail, when the oil pressure of the oil discharged from the oil pump 1 is 0 (when the pressing force is 0), such as when the engine is started. Further, it is provided for transmitting torque from the second shaft 18 to the first shaft 16. The urging force of the urging portion 24 is set to such an extent that torque can be transmitted from the second shaft 18 to the first shaft 16 when the engine is started.

  In the casing 28, a housing hole 28c that opens toward the cover 12 is formed at a position facing the first shaft 16, and a communication hole 28d that connects the discharge flow path 28b and the housing hole 28c is formed. Has been done.

  A pressing portion 26 is provided in the accommodation hole 28c, and a seal portion 40 is provided between the inner peripheral surface of the accommodation hole 28c and the outer peripheral surface of the pressing portion 26. The pressing portion 26 is formed of, for example, a piston, and the contact surface 26a is in contact with the end surface of the first shaft 16, and the rear surface 26b opposite to the contact surface 26a is arranged to face the communication hole 28d.

  Therefore, when the oil pump 1 is driven and the oil is discharged to the discharge passage 38, the hydraulic pressure generated in the discharge passage 38 acts on the back surface 26b of the pressing portion 26 via the communication hole 28d. As a result, the pressing unit 26 presses the first shaft 16 toward the second shaft 18 with a pressing force proportional to the hydraulic pressure in the discharge flow path 38.

  Accordingly, the friction member 22 generates a frictional force between the first shaft 16 and the second shaft 18, and the frictional force transmits the torque from the second shaft 18 to the first shaft 16.

The area of the back surface 26b of the pressing portion 26 is determined based on the following equations (1) to (3) so that the pump drive torque is higher than the maximum transmission torque when the engine has a predetermined rotation speed (for example, 2000 rpm) or more. Is also set to be large.
Pressing force of pressing portion 26 = hydraulic pressure of discharge passage 38 × area of back surface 26b of pressing portion 26 (1)
Maximum transmission torque = pressing force of pressing portion 26 × friction coefficient of friction member 22 × friction area of friction member 22 (2)
Pump drive torque = oil dynamic torque (oil pressure in discharge passage 38 × flow rate / rotational speed of first shaft 16) + friction torque (3)

  FIG. 2 is a diagram showing the relationship between the engine speed and the flow rate. Here, the flow rate of oil discharged by the oil pump 1 will be described together with the operation of the oil pump 1.

  As described above, the oil pump 1 does not discharge oil when the engine is started, so the oil pressure in the discharge passage 38 is zero. Then, when the engine is started, the second shaft 18 is rotated along with the rotation of the engine. At this time, in the oil pump 1, the urging force of the urging portion 24 causes the friction member 22 to generate a friction force. Torque is transmitted from the second shaft 18 to the first shaft 16.

  Then, in the oil pump 1, the first shaft 16 is rotationally driven, and the oil stored in the oil pan 32 is pumped up by the rotating body 14 through the suction flow passage 36 and discharged to the discharge flow passage 38 to be discharged. The hydraulic pressure of 38 rises.

  When the hydraulic pressure of the discharge flow path 38 rises, the hydraulic pressure acts on the back surface 26b of the pressing portion 26 via the communication hole 28d, and the pressing portion 26 generates a pressing force for pressing the first shaft 16 against the second shaft 18. After the engine is started, the friction member 22 transmits the torque from the second shaft 18 to the first shaft 16 by the pressing force generated by the pressing portion 26.

  Then, as the rotational speed of the engine increases, the rotational speeds of the second shaft 18 and the first shaft 16 also increase, and as shown in FIG. 2, the flow rate of the oil discharged by the rotating body 14 increases. F1 will also rise.

  Further, when the engine speed reaches a predetermined engine speed N1 (for example, 2000 rpm) and the torque transmitted from the second shaft 18 to the first shaft 16 reaches the maximum transmission torque, the friction member 22 begins to slide. When the friction member 22 starts to slide, the torque transmitted by the friction member 22 becomes the maximum transmission torque, and the rotation speed of the first shaft 16 becomes constant regardless of the rotation speed of the engine. Further, since the friction member 22 is set to slide when the area of the back surface 26b of the pressing portion 26 becomes larger than the required flow rate F2, the flow rate F1 of the oil discharged by the rotating body 14 is also required. It becomes constant when the flow rate is higher than F2.

  On the other hand, as a comparative example, in the case of an oil pump in which the shaft that rotates integrally with the rotor rotates in proportion to the engine speed, the oil flow rate F3 also increases in proportion to the engine speed. A large amount of oil than the required flow rate F2 will be supplied to the transmission, and cavitation will occur.

  On the other hand, the oil pump 1 maintains the flow rate F1 that is substantially the same as the required flow rate F2 even if the engine speed increases, so that cavitation can be suppressed and the engine rotation speed can be reduced. It is possible to prevent the oil flow rate F1 from increasing in accordance with the number.

  FIG. 3 is a diagram showing the relationship between the engine speed and the torque when the hydraulic pressure in the discharge passage 38 is constant. When the hydraulic pressure in the discharge passage 38 is kept constant by the valve 42, the maximum transmission torque T1 that can be transmitted from the second shaft 18 to the first shaft 16 is always constant regardless of the engine speed.

  Further, the oil dynamic torque T2 for the rotary body 14 to pump up the oil is always constant under the condition that the hydraulic pressure of the discharge passage 38 is constant, regardless of the engine speed. Further, the friction torque T3 generated between the rotor 14 and the body 10 and the cover 12 increases in proportion to the rotation speed of the first shaft 16, and the maximum transmission torque T1, the hydraulic torque T2, and the friction torque T1. When the sum of T3, that is, the pump driving torque acting on the first shaft 16 for driving the rotating body 14 is balanced, the friction member 22 starts to slide and becomes constant.

  After that, even if the rotation speed of the engine increases, the rotation speed of the first shaft 16 becomes constant, so that the friction torque T3 also becomes constant.

  On the other hand, as a comparative example, in the case of an oil pump in which the shaft that rotates integrally with the rotor rotates in proportion to the engine speed, the friction torque T4 also increases in proportion to the engine speed.

  On the other hand, the oil pump 1 prevents the friction torque T4 from increasing as the engine speed increases, and compares with the case where the friction torque T4 increases in proportion to the engine speed. T3 can be reduced.

  FIG. 4 is a diagram illustrating a change in torque when it is assumed that the engine speed is constant. As shown in FIG. 4, under the condition that the engine speed N11 is constant, for example, when the hydraulic pressure P1 of the discharge flow path 38 is reduced at time S1, the hydraulic pressure acting on the pressing portion 26 is also reduced. The pressing force acting on the first shaft 16 by 26 is also reduced. As a result, the transmission torque (maximum transmission torque) T11 transmitted from the second shaft 18 to the first shaft 16 by the friction member 22 also decreases. Further, as the transmission torque T11 decreases, the oil dynamic torque T12 of the rotating body 14 also decreases, but the rotation speed N12 of the first shaft 16 is kept constant and the friction torque T13 is also kept constant. Be drunk

  On the other hand, for example, when the hydraulic pressure P1 of the discharge flow path 38 rises at time S2, the hydraulic pressure acting on the pressing portion 26 also rises, so that the pressing force acting on the first shaft 16 by the pressing portion 26 also increases. As a result, the transmission torque (maximum transmission torque) T11 transmitted from the second shaft 18 to the first shaft 16 by the friction member 22 also increases. Further, as the transmission torque T11 increases, the oil dynamic torque T12 of the rotating body 14 also increases, but the rotation speed N12 of the first shaft 16 is kept constant and the friction torque T13 is also kept constant. Be drunk

  As a result, the oil pump 1 does not decrease the rotation speed of the first shaft 16 even if the oil pressure P1 of the discharge passage 38 increases and the oil dynamic torque of the oil pump 1 increases, so that the oil pump 1 has a fixed amount. The flow rate (discharge amount) can be maintained.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications within the scope of the claims. It goes without saying that the modified examples also belong to the technical scope of the present invention.

  In the above embodiment, the transmission has been described as an example of the oil supply destination, but the present invention is not limited to this, and the present invention can be applied to an oil pump that supplies oil to an engine.

  Further, although the case where the oil pump 1 is the internal gear pump has been described in the above embodiment, the present invention is not limited to this, and the present invention can be applied to an oil pump in which oil is pumped up by a rotating body such as an external gear pump or a vane pump. it can.

  Further, in the above embodiment, the first shaft 16 and the pressing portion 26 are provided as separate bodies, but the present invention is not limited to this, and the first shaft 16 and the pressing portion 26 may be integrated. That is, the first shaft 16 may function as the pressing portion 26.

  Further, in the above embodiment, the urging portion 24 urges the second shaft 18 to the first shaft 16, but the present invention is not limited to this, and the urging portion 24 causes the first shaft 16 to move to the second shaft 18. You may make it urge. That is, the urging portion 24 urges one of the first shaft 16 and the second shaft 18 to the other of the first shaft 16 and the second shaft 18 at the time of starting the engine, and the friction member 22 transmits the torque. It should be possible to do it.

  INDUSTRIAL APPLICATION This invention can be utilized for the oil pump driven by an engine.

1 Oil Pump 16 First Shaft 18 Second Shaft 22 Friction Member 24 Energizing Part 26 Pressing Part

Claims (2)

Pumping the oil from the suction passage, a rotating body for discharging the oil in the discharge passage,
A first shaft that rotates integrally with the rotating body;
A second shaft arranged coaxially with the first shaft and rotated by the engine;
A friction member arranged between the first shaft and the second shaft , for transmitting torque between the first shaft and the second shaft by a frictional force;
An urging portion that urges the second shaft toward the first shaft so that torque can be transmitted when the engine is started;
A pressing portion that presses the first shaft against the second shaft by hydraulic pressure in the discharge flow path;
An oil pump comprising: The friction member is
If the maximum transmission torque or torque transmitted to the first shaft from said second shaft is transmitted from said second shaft, said the maximum torque transfer slides between said first shaft and said second shaft The oil pump according to claim 1, wherein the oil pump transmits the oil to the first shaft.

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