JP2010255467A - Vacuum pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vane type vacuum pump capable of reducing power loss even in a low speed zone and even in a high speed zone. <P>SOLUTION: A vacuum pump 10 includes a casing 11a having a plurality of pump chambers 14, 14 formed therein, and a rotor 12 eccentrically disposed in the casing 11a and slidably retaining a vane 13. Lubricating oil is supplied into the casing 11a through a lubrication path, and lubricating oil is discharged from an inside of the casing 11a through a discharge port 16. An open close valve 17 opening and closing the discharge port according to pressure of compressed air to be discharged is disposed at the discharge port 16. The pump includes a change device 20 varying discharge timing of lubricating oil from the discharge port 16 according to speed of an internal combustion engine 1 and discharge timing of the lubricating oil is advanced in the high speed zone as compared to that in the low speed zone. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vane type vacuum pump.

  The vane-type vacuum pump has, for example, a configuration in which a vane that is slidably in contact with an inner peripheral surface of a casing is attached to a rotor as disclosed in Patent Document 1. In such a vacuum pump, lubricating oil is supplied into the pump chamber through an oil supply passage in order to ensure airtightness inside the casing and lubricity of sliding parts such as the rotor and vanes. The

  When rotation is transmitted from a driving source such as an engine and the rotor rotates, negative pressure is generated, while compressed air is discharged from the discharge port of the casing to the outside. At this time, compressed air mixed with lubricating oil is discharged from the discharge port. An opening / closing valve such as a reed valve is provided at the discharge port of the casing in order to improve the airtightness in the casing and the sealing performance of the lubricating oil to reduce the driving torque of the rotor.

JP 2006-118424 A

  As described above, in the vane type vacuum pump, the lubricating oil is supplied into the pump chamber through the oil supply passage, or the lubricating oil is discharged from the pump chamber through the discharge port. However, since the friction characteristics with respect to the amount of lubricating oil present in the pump chamber are different between the low rotation range where the rotor rotation speed is low and the high rotation range where the rotor rotation speed is high, there is a possibility that power loss may increase. There is.

  Specifically, in the low rotation range, if the amount of lubricating oil in the pump chamber is insufficient, airtight leakage is likely to occur due to the clearance between the vane and the casing (housing). For this reason, there is a concern that the driving torque of the rotor increases and the power loss increases.

  On the other hand, when the amount of lubricating oil in the pump chamber increases in the high rotation region, the discharge load of excess lubricating oil increases and the internal pressure in the pump chamber increases. For this reason, there is a concern that friction increases and power loss increases.

  The present invention has been made in view of such problems, and an object thereof is to provide a vane-type vacuum pump capable of reducing power loss even in a low rotation range or a high rotation range. To do.

  In the present invention, means for solving the above-described problems are configured as follows. That is, the present invention includes a casing in which a plurality of pump chambers are formed, and a rotor that is eccentrically provided in the casing and that slidably holds the vane. An oil supply passage is provided in the casing. On the other hand, the lubricating oil is supplied through the casing, and from the inside of the casing, the lubricating oil is discharged through the outlet, and the outlet is an on-off valve that opens and closes the outlet according to the pressure of the compressed air to be discharged. Is provided with a change mechanism that makes variable at least one of the discharge timing and the discharge amount of the lubricating oil from the discharge port according to the rotation speed, and the change mechanism is A vacuum pump characterized in that the discharge timing is increased and the discharge amount is increased as compared with the case of the low rotation range.

  According to the above configuration, in the low rotation region, it is possible to suppress the shortage of the lubricating oil in the pump chamber by delaying the discharge timing of the lubricating oil from the discharge port as compared with the case of the high rotation region. Moreover, it can suppress that lubricating oil runs short in a pump chamber by reducing the discharge amount of lubricating oil from a discharge port. Thereby, the clearance between the vane and the casing can be reliably sealed, and the occurrence of airtight leakage can be suppressed. As a result, in the vacuum pump, the driving torque of the rotor can be reduced and the power loss can be reduced.

  On the other hand, in the high rotation region, the lubricating oil in the pump chamber can be discharged quickly by increasing the discharge timing of the lubricating oil from the discharge port as compared with the low rotation region. Moreover, the lubricating oil in the pump chamber can be quickly discharged by increasing the amount of the lubricating oil discharged from the discharge port. Thereby, it can suppress that the discharge load of excess lubricating oil increases, and it can suppress that the internal pressure in a pump chamber increases. As a result, in the vacuum pump, friction can be reduced and power loss can be reduced.

  In the present invention, it is preferable that the changing mechanism is configured so that the opening area of the open side of the opening / closing valve of the discharge port is larger in the high rotation range than in the low rotation range.

  According to this configuration, in the low rotation range, the timing of discharging the lubricating oil from the discharge port can be delayed by reducing the opening area of the region on the opening side of the discharge port compared to the case of the high rotation range. Since it can do, it can control that lubricating oil runs short in a pump room. Moreover, since the discharge amount of the lubricating oil from the discharge port can be reduced by reducing the opening area of the region on the opening side of the discharge port, it is possible to suppress the shortage of the lubricating oil in the pump chamber. Thereby, the clearance between the vane and the casing can be reliably sealed, and the occurrence of airtight leakage can be suppressed. As a result, in the vacuum pump, the driving torque of the rotor can be reduced and the power loss can be reduced.

  On the other hand, in the high rotation region, compared with the low rotation region, by increasing the opening area of the region on the opening side of the discharge port, it is possible to accelerate the discharge timing of the lubricating oil from the discharge port, Lubricating oil in the pump chamber can be quickly discharged. Moreover, since the amount of lubricating oil discharged from the outlet can be increased by increasing the opening area of the region on the opening side of the outlet, the lubricating oil in the pump chamber can be quickly discharged. Thereby, it can suppress that the discharge load of excess lubricating oil increases, and it can suppress that the internal pressure in a pump chamber increases. As a result, in the vacuum pump, friction can be reduced and power loss can be reduced.

  In the present invention, the changing mechanism includes a moving member that protrudes and retracts into a region on the opening side of the opening / closing valve of the discharge port by hydraulic pressure, and in the high rotation range, the movement member It is preferable that the amount of protrusion of the discharge port on the opening side of the opening / closing valve is reduced. Examples of such an on-off valve include a reed valve provided with a leaf spring that covers the discharge port.

  According to the above configuration, the amount of protrusion of the moving member into the open side region is larger in the low rotation range than in the high rotation range, so the opening area of the open side region of the discharge port is small. Become. For this reason, the discharge timing of the lubricating oil from the discharge port can be delayed, and the shortage of lubricating oil in the pump chamber can be suppressed. In addition, the amount of lubricating oil discharged from the discharge port can be reduced, and the shortage of lubricating oil in the pump chamber can be suppressed. Thereby, the clearance between the vane and the casing can be reliably sealed, and the occurrence of airtight leakage can be suppressed. As a result, in the vacuum pump, the driving torque of the rotor can be reduced and the power loss can be reduced.

  On the other hand, in the high rotation range, the amount of protrusion of the moving member into the open side region is smaller than in the low rotation range, so that the opening area of the open side region of the discharge port is large. For this reason, the discharge timing of the lubricating oil from the discharge port can be advanced, and the lubricating oil in the pump chamber can be discharged quickly. Further, the amount of lubricating oil discharged from the discharge port can be increased, and the lubricating oil in the pump chamber can be quickly discharged. Thereby, it can suppress that the discharge load of excess lubricating oil increases, and it can suppress that the internal pressure in a pump chamber increases. As a result, in the vacuum pump, friction can be reduced and power loss can be reduced.

  According to the present invention, in a vane type vacuum pump, it is possible to reduce power loss even in a low rotation range and a high rotation range.

It is sectional drawing which shows the vacuum pump which concerns on embodiment. It is a front view which shows the casing inside of the vacuum pump of FIG. It is a figure which shows typically the opening / closing valve provided in the discharge port of the casing of FIG. 2, and the change mechanism which makes variable the discharge timing of the lubricating oil from a discharge port. It is a figure which divides and shows the open state of the on-off valve of FIG. 3 in a low rotation area and a high rotation area.

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

  Below, the example which installed the vacuum pump of this invention in the internal combustion engine mounted in vehicles, such as a motor vehicle, is demonstrated. In an internal combustion engine, a vacuum pump is provided at one end of a camshaft, for example. Then, the rotational driving force generated in the internal combustion engine is transmitted to the camshaft through a timing chain or the like, so that the vacuum pump is driven and negative pressure is generated. The negative pressure generated by the vacuum pump is used, for example, for a brake booster mounted on a vehicle.

  First, a schematic configuration of the vacuum pump 10 according to the embodiment will be described. As shown in FIGS. 1 and 2, the vacuum pump 10 is configured as a vane-type vacuum pump.

  The vacuum pump 10 includes a housing 11 that is fixed to a side surface of the internal combustion engine 1. The housing 11 is formed in a cylindrical shape having a stepped portion. Specifically, as shown in FIG. 1, the housing 11 has a configuration in which a large-diameter casing 11a and a small-diameter bearing portion 11b continuous therewith are integrally formed. The bearing portion 11 b of the housing 11 is fitted from the outside of the internal combustion engine 1 into a through hole 1 a formed on the side surface of the internal combustion engine 1. The front opening of the casing 11a of the housing 11 is covered with a cover 11c.

  A rotor 12 is accommodated in the housing 11. A through hole 11d that fits in the axial direction is formed at the center of the bearing portion 11b of the housing 11, and the rotor shaft 12a of the rotor 12 is inserted into the through hole 11d. The rotor shaft 12a is rotatably supported by the bearing portion 11b.

  The shape of the inner peripheral surface 11e of the casing 11a is formed such that the distance between two points on the inner peripheral surface 11e where both ends of the vane 13 to be described later contact each other is substantially constant at all rotational positions of the rotor 12. Yes. Specifically, the shape of the inner peripheral surface 11e is an ellipse or a deformed circle.

  As shown in FIG. 2, the rotor 12 is arranged so as to rotate at a position eccentric with a predetermined eccentricity with respect to the casing 11 a. In FIG. 2, the rotor 12 is eccentric to the right with respect to the casing 11a.

  As shown in FIG. 1, the portion 12b accommodated in the casing 11a of the rotor 12 is formed with a larger diameter than the rotor shaft 12a, and a vane groove 12c extending in the radial direction is formed in the portion 12b. Yes. As shown in FIG. 2, a flat vane 13 is slidably fitted into the vane groove 12c. The vane 13 is provided in the rotor 12 so that the tip thereof can move along the inner peripheral surface 11e of the casing 11a. Note that seal members 13 a are respectively attached to both tip portions of the vane 13.

  As shown in FIG. 2, the interior of the casing 11 a is partitioned into two pump chambers 14 and 14 by the vane 13. Specifically, the vane 13 receives a centrifugal force in a direction protruding from the vane groove 12c as the rotor 12 rotates (in FIG. 2, the rotation direction is indicated by an arrow X1). Thus, the vane 13 enters and exits the vane groove 12c while the tip of the vane 13 (seal member 13a) and the inner peripheral surface 11e of the casing 11a are in sliding contact. And between the inner peripheral surface 11e of the casing 11a eccentric to each other and the outer peripheral surface of the rotor 12, a sealed space whose width dimension continuously changes along the circumferential direction, that is, two pump chambers 14 and 14 are formed. Is done.

  Thus, when the vane 13 rotates in the X1 direction as the rotor 12 rotates, the volumes of the pump chambers 14 and 14 change continuously. In this case, one volume of the pump chambers 14 and 14 is increased, and the other volume is decreased.

  As shown in FIG. 1, the rotor shaft 12 a of the rotor 12 is coupled to one end of a camshaft (for example, intake camshaft) 2 of the internal combustion engine 1 via a coupling 3 so as to be integrally rotatable. An oil supply path 2 a for supplying lubricating oil is formed inside the camshaft 2. The oil supply passage 2 a is connected to lubricating oil supply means provided in the internal combustion engine 1.

  The rotor shaft 12a is formed with a through hole 12d penetrating in the radial direction. A recess 12e is formed at the center of the rotor shaft 12a, and the recess 12e and the through hole 12d are communicated with each other. One end of an oil supply pipe 15 having an oil supply passage 15a formed therein is fitted in the recess 12e of the rotor shaft 12a via an O-ring. Further, the other end of the oil supply pipe 15 is fitted into a recess 2b formed at the center of the camshaft 2 via an O-ring. The oil supply passage 2a of the camshaft 2, the oil supply passage 15a of the oil supply pipe 15, and the through-hole 12d of the rotor shaft 12a of the rotor 12 are always in communication.

  Further, as shown in FIG. 1, a pair of communication grooves 11 f and 11 f extending in the axial direction are formed in the bearing portion 11 b of the housing 11 at substantially diagonal positions on the inner peripheral surface. One end of the communication grooves 11f and 11f extends in the axial direction to the position of the through hole 12d of the rotor shaft 12a. The communication grooves 11f and 11f communicate with the through hole 12d of the rotor shaft 12a intermittently as the rotor 12 rotates. The other ends of the communication grooves 11f and 11f communicate with the casing 11a.

  In the vacuum pump 10, the lubricating oil is supplied into the pump chamber 14 through these oil supply passages 2a and 15a, the through hole 12d, and the communication groove 11f. In this case, when the through hole 12d of the rotor 12 communicates with the communication groove 11f of the bearing portion 11b, the lubricating oil is supplied into the pump chamber 14 from the through hole 12d through the communication groove 11f. Thus, the supply of the lubricating oil from the oil supply passage 2a of the camshaft 2 into the pump chamber 14 is performed intermittently.

  As shown in FIGS. 2 and 3, the casing 11 a is provided with a discharge port 16 for discharging compressed air. The discharge port 16 is formed in the bottom wall of the casing 11a. The discharge port 16 is formed in a long hole extending substantially linearly, and extends from the vicinity of the position P1 where the rotor 12 and the casing 11a are closest to each other toward the rear side (downstream side) of the vane 13 in the rotation direction. ing. That is, the discharge port 16 is provided on the side of the pump chamber 14 whose volume tends to decrease. The compressed air in the pump chamber 14 is discharged into the internal combustion engine 1 through the discharge port 16. The cross section of FIG. 3 is a cross section taken along line X2-X2 of FIG.

  As shown in FIG. 3, an opening / closing valve 17 that opens and closes according to increase / decrease in the pressure (internal pressure) of compressed air in the pump chamber 14 is attached to the discharge port 16. As the on-off valve 17, for example, a reed valve that opens so as to bend according to the internal pressure of the pump chamber 14 is used. As shown in FIG. 3, the on-off valve 17 includes a thin leaf spring 17 a that covers the discharge port 16. One end side in the longitudinal direction of the leaf spring 17a (right end side in FIG. 3) is fixed to the bottom wall portion of the casing 11a by screwing, but the other end side in the longitudinal direction (left end side in FIG. 3) is The casing 11a can move freely.

  In the closed state of the on-off valve 17, as shown in FIG. 3, the leaf spring 17a extends straight so as to close the discharge port 16. In the open state of the on-off valve 17, as shown in FIGS. 4A and 4B, the leaf spring 17a is bent so as to open the discharge port 16. Then, the compressed air mixed with the lubricating oil in the pump chamber 14 is discharged from the discharge port 16 into the internal combustion engine 1. Thus, by providing the opening / closing valve 17 and opening the discharge port 16 intermittently without always opening the discharge port 16, the air tightness of the pump chamber 14 and the sealing performance of the lubricating oil are improved, and the pump performance. And the driving torque of the rotor 12 can be reduced.

  Further, as shown in FIG. 2, the casing 11a is provided with a suction port 18 for taking out negative pressure. The suction port 18 is on the opposite side of the discharge port 16 with the rotor 12 interposed therebetween, specifically, on the front side (upstream side) in the rotational direction of the vane 13 from the position P1 where the rotor 12 and the casing 11a are closest to each other. Is provided. That is, the suction port 18 is provided on the pump chamber 14 side where the volume tends to increase. The suction port 18 is connected to a device (for example, a brake booster) that requires negative pressure through the suction passage 18a.

  In this embodiment, the vacuum pump 10 is provided with a changing device 20 that makes the discharge timing for discharging the lubricating oil from the discharge port 16 of the casing 11a variable. The changing device 20 is configured to change the opening area of the opening 16 (on the side opposite to the root side) of the opening / closing valve 17 of the discharge port 16 (hereinafter simply referred to as the opening side region) 16a, thereby changing the discharge area. The discharge timing at which the lubricating oil is discharged from the outlet 16 is changed. Hereinafter, the characteristic part of this embodiment will be described in detail.

  As shown in FIG. 3, the changing device 20 includes a piston (moving member) 21, a spring 22, and a hydraulic chamber 23. The hydraulic chamber 23 is formed inside the bottom wall portion of the casing 11 a and is provided in the vicinity of the open side region 16 a of the discharge port 16.

  The piston 21 is inserted into the hydraulic chamber 23, and one end portion (right end portion in FIG. 3) 21 a thereof is disposed so as to protrude into and out of the opening side region 16 a of the discharge port 16. The other end (left end in FIG. 3) of the piston 21 is connected to a spring 22 disposed in the hydraulic chamber 23. The urging force of the spring 22 acts in a direction (in the left direction in FIG. 3) to reduce the amount of protrusion of the one end 21a of the piston 21 into the opening side region 16a of the discharge port 16. In other words, the urging force of the spring 22 acts in the direction of increasing the opening area of the open side region 16a of the discharge port 16.

  The piston 21 slides by the balance between the urging force of the spring 22 and the hydraulic pressure of the hydraulic chamber 23. Thereby, the protrusion amount into the opening side area | region 16a of the discharge port 16 of the piston 21 is changed, and the opening area of the opening side area | region 16a of the discharge port 16 is changed.

  The hydraulic chamber 23 is connected to, for example, lubricating oil supply means provided in the internal combustion engine 1 via an oil passage 24. In the middle of the oil passage 24, a control valve 25 controlled by the ECU 30 is interposed. The ECU 30 includes a CPU that performs calculations, a RAM that stores various types of information such as calculation results, a backup RAM in which the stored contents are held by a battery, and a ROM that stores various control programs and maps.

  The ECU 30 is connected to a rotation speed sensor 31 that detects the rotation speed (engine speed) of the internal combustion engine 1. The ECU 30 controls the control valve 25 based on the rotational speed of the internal combustion engine 1 detected by the rotational speed sensor 31. And by controlling the hydraulic pressure supplied to the hydraulic chamber 23 under the control of the control valve 25, the piston 21 slides.

  Specifically, when the hydraulic pressure in the hydraulic chamber 23 is increased, for example, the piston 21 slides to the right against the urging force of the spring 22 as shown in FIG. Thereby, the protrusion amount into the opening side area | region 16a of the discharge port 16 of the piston 21 becomes large. And the opening side area | region 16a of the discharge port 16 is closed by the part which the protrusion amount became large, and the opening area of this opening side area | region 16a becomes small.

  On the contrary, when the hydraulic pressure in the hydraulic chamber 23 is lowered, for example, as shown in FIG. 4B, the piston 21 slides to the left by the urging force of the spring 22. Thereby, the protrusion amount into the opening side area | region 16a of the discharge port 16 of the piston 21 becomes small. And the opening side area | region 16a of the discharge port 16 is open | released by the part which the protrusion amount became small, and the opening area of this opening side area | region 16a becomes large.

  In this embodiment, the changing device 20 changes the opening area of the opening side region 16a of the discharge port 16 between low rotation and high rotation. When the internal combustion engine 1 is a four-cycle engine, the rotational speed of the rotor 12 is half of the rotational speed of the internal combustion engine 1 (the rotational speed of the crankshaft). For this reason, in this embodiment, the opening area of the open side region 16a of the discharge port 16 is changed based on the rotational speed of the internal combustion engine 1 detected by the rotational speed sensor 31. FIGS. 4A and 4B show how the on-off valve 17 opens at the same pressure.

  Specifically, the ECU 30 supplies the hydraulic chamber 23 by controlling the control valve 25 in a low rotation range where the rotation speed of the internal combustion engine 1 detected by the rotation speed sensor 31 is less than a preset threshold value N1. Increase hydraulic pressure. Then, as shown in FIG. 4A, the piston 21 moves to the right. FIG. 4A shows a state where the piston 21 has moved to the right as much as possible.

  Thereby, the opening area of the opening side area | region 16a of the discharge port 16 becomes small. For this reason, as shown in FIG. 4A, the leaf spring 17a is less likely to bend even when the internal pressure of the pump chamber 14 increases with the rotation of the vane 13, as compared with the case of the high rotation region described later. That is, the on-off valve 17 is difficult to open, and the timing at which the on-off valve 17 starts to open is delayed. Therefore, the discharge timing at which the lubricating oil is discharged from the discharge port 16 is delayed.

  In this way, in the low rotation range, by reducing the opening area of the opening side region 16a of the discharge port 16, the discharge timing of the lubricating oil from the discharge port 16 can be delayed, so lubrication is performed in the pump chamber 14. The shortage of oil can be suppressed. Thereby, the clearance between the vane 13 and the casing 11a can be reliably sealed, and the occurrence of airtight leakage can be suppressed. As a result, in the vacuum pump 10, the driving torque of the rotor 12 can be reduced, and the power loss can be reduced.

  On the other hand, the ECU 30 controls the control valve 25 to lower the hydraulic pressure supplied to the hydraulic chamber 23 in a high rotation range where the rotation speed of the internal combustion engine 1 detected by the rotation speed sensor 31 is equal to or higher than the threshold value N1. Then, as shown in FIG. 4B, the piston 21 moves to the left. FIG. 4B shows a state in which the piston 21 has moved to the left as much as possible. In this state, the protruding amount of the piston 21 to the opening side region 16a of the discharge port 16 is “0”. .

  Thereby, the opening area of the opening side area | region 16a of the discharge port 16 becomes large. For this reason, when the internal pressure of the pump chamber 14 increases with the rotation of the vane 13 as compared with the case of the low rotation region described above, the leaf spring 17a is easily bent as shown in FIG. That is, the opening / closing valve 17 is easily opened, and the opening timing of the opening / closing valve 17 is accelerated. Therefore, the discharge timing at which the lubricating oil is discharged from the discharge port 16 is accelerated.

  As described above, in the high rotation range, by increasing the opening area of the opening side region 16a of the discharge port 16, the discharge timing of the lubricating oil from the discharge port 16 can be advanced, and the lubricating oil in the pump chamber 14 can be accelerated. Can be discharged promptly. Thereby, it can suppress that the discharge load of excess lubricating oil increases, and it can suppress that the internal pressure in pump 14 room | chamber interior increases. As a result, in the vacuum pump 10, friction can be reduced and power loss can be reduced.

  In the above, an example in which the discharge timing for discharging the lubricating oil from the discharge port 16 of the casing 11a by the changing device 20 is changed to two stages has been described, but the discharge timing of the lubricating oil from the discharge port 16 is changed to three or more stages. It is good also as composition to do. Further, the timing for discharging the lubricating oil from the discharge port 16 may be continuously changed according to the rotational speed of the internal combustion engine 1. In this case, the timing for discharging the lubricating oil from the discharge port 16 may be advanced as the rotational speed of the internal combustion engine 1 increases. Specifically, the hydraulic pressure in the hydraulic chamber 23 may be controlled so that the opening area of the open side region 16a of the discharge port 16 increases as the rotational speed of the internal combustion engine 1 increases.

  The changing device 20 may have a configuration other than the above as long as the opening area of the opening side region 16a of the discharge port 16 can be changed. For example, a shielding plate that covers the opening side region 16a of the discharge port 16 may be provided, and the opening area of the opening side region 16a of the discharge port 16 may be changed by rotating (moving) the shielding plate. Further, means other than hydraulic pressure may be used as means for moving the moving member such as the piston 21.

-Other embodiments-
The embodiment of the present invention has been described above. However, the embodiment shown here is an example and can be variously modified.

  (1) In the above-described embodiment, the example in which the discharge timing of the lubricating oil from the discharge port 16 is changed according to the rotational speed of the internal combustion engine 1 has been described, but from the exhaust port 16 according to the rotational speed of the internal combustion engine 1 By changing the discharge amount of the lubricating oil, it is possible to reduce the power loss in the vacuum pump 10 in both the low rotation range and the high rotation range.

  For example, a change device having substantially the same configuration as the change device 20 of the above-described embodiment may be provided, and the opening area of the discharge port 16 may be changed according to the number of revolutions of the internal combustion engine 1 by this change device. Specifically, the opening area of the discharge port 16 may be made larger in the high rotation range than in the low rotation range. In this case, unlike the above embodiment, the opening area of the region other than the opening side region 16a of the discharge port 16 may be changed.

  And, in the low rotation range, the amount of the lubricating oil discharged from the discharge port 16 can be reduced by reducing the opening area of the discharge port 16, thereby suppressing the shortage of the lubricating oil in the pump chamber 14. it can. Thereby, in the vacuum pump 10, the drive torque of the rotor 12 can be reduced and the power loss can be reduced.

  On the other hand, by increasing the opening area of the discharge port 16 in the high rotation range, the amount of lubricating oil discharged from the discharge port 16 can be increased, and the lubricating oil in the pump chamber 14 can be discharged quickly. it can. Thereby, in the vacuum pump 10, friction can be reduced and reduction of power loss can be aimed at.

  In addition, it is good also as a structure which changes the discharge amount of the lubricating oil from the discharge port 16 in three steps or more. Further, the amount of lubricating oil discharged from the discharge port 16 may be continuously changed according to the rotational speed of the internal combustion engine 1. In this case, the opening area of the discharge port 16 may be increased as the rotational speed of the internal combustion engine 1 increases. Further, the change device may have any configuration as long as the change amount of the lubricating oil discharged from the discharge port 16 can be changed. For example, the lubricant discharge amount may be changed using a moving member other than the piston, or the lubricant discharge amount may be changed using a means other than the hydraulic pressure.

  (2) Further, by changing the discharge timing and discharge amount of the lubricating oil from the discharge port 16 in accordance with the rotational speed of the internal combustion engine 1, the vacuum pump 10 can reduce power loss in both a low rotation range and a high rotation range. It is also possible to plan. For example, according to the change device 20 of the above embodiment, in addition to the timing of discharging the lubricating oil from the discharge port 16, the discharge amount is also changed.

  Specifically, in the low rotation range, as shown in FIG. 4A, the amount of protrusion of the piston 21 into the open side region 16a of the discharge port 16 increases, and the opening area of the discharge port 16 decreases. For this reason, the opening degree of the on-off valve 17 becomes small even at the same pressure as compared with the case of the high rotation range shown in FIG. Accordingly, the amount of lubricating oil discharged from the discharge port 16 is reduced.

  In this way, by reducing the opening area of the open side region 16a of the discharge port 16 in the low rotation range, the discharge timing of the lubricating oil from the discharge port 16 can be delayed and the discharge amount can be reduced. The shortage of lubricating oil in the chamber 14 can be suppressed. Thereby, in the vacuum pump 10, the drive torque of the rotor 12 can be reduced and the power loss can be reduced.

  On the other hand, in the high rotation region, as shown in FIG. 4B, the amount of protrusion of the discharge port 16 of the piston 21 into the open side region 16a decreases, and the opening area of the discharge port 16 increases. For this reason, compared with the case of the low rotation range shown in FIG. Accordingly, the amount of lubricating oil discharged from the discharge port 16 increases.

  Thus, by increasing the opening area of the opening side region 16a of the discharge port 16 in the high rotation region, the discharge timing of the lubricating oil from the discharge port 16 can be accelerated and the discharge amount can be increased. The lubricating oil in 14 can be quickly discharged. Thereby, in the vacuum pump 10, friction can be reduced and reduction of power loss can be aimed at.

  (3) In the above embodiment, the example of changing the discharge timing or discharge amount of the lubricating oil from the discharge port 16 has been described, but the intake timing or suction amount of the lubricating oil sucked into the casing 11a is set as the internal combustion engine 1. By changing according to the number of rotations, it is possible to reduce power loss in both the low and high rotation ranges. For example, in the high rotation range, the amount of lubricating oil present in the pump chamber 14 is reduced by delaying the suction timing of the lubricating oil sucked into the casing 11a as compared with the low rotation range, thereby reducing the friction. Reduction can be achieved. Alternatively, in the high speed range, the amount of lubricating oil sucked into the casing 11a is reduced compared to the low speed range, thereby reducing the amount of lubricating oil present in the pump chamber 14 and reducing the friction. Reduction is also possible.

  (4) In the above, the example in which the internal combustion engine 1 is used as the drive source of the vacuum pump 10 has been described. However, the vacuum pump 10 may be driven by a drive source different from the internal combustion engine 1. The usage target of the vacuum pump 10 according to the present invention is not limited to the brake booster of the vehicle, and may be an appropriate machine or the like that requires negative pressure.

  The present invention can be used for a vane type vacuum pump. Specifically, the present invention is useful as a technique for reducing power loss in both a low rotation range and a high rotation range.

DESCRIPTION OF SYMBOLS 10 Vacuum pump 11 Housing 11a Casing 12 Rotor 13 Vane 14 Pump chamber 16 Discharge port 16a Open side area 17 On-off valve 20 Changing device 21 Piston 23 Hydraulic chamber 31 Rotation speed sensor

Claims (4)

A casing in which a plurality of pump chambers are formed;
A rotor that is eccentrically provided in the casing and holds the vane slidably,
Lubricating oil is supplied into the casing through an oil supply passage, while lubricating oil is discharged from the casing through a discharge port, and the discharge port is responsive to the pressure of the compressed air to be discharged. A vacuum pump provided with an open / close valve for opening and closing the lever outlet;
A change mechanism for changing at least one of the discharge timing and the discharge amount of the lubricating oil from the discharge port according to the rotational speed;
The said change mechanism is a vacuum pump characterized by being comprised so that discharge | emission timing may be early | stimulated and the amount of discharge | emissions may be increased compared with the case of a low rotation area in a high rotation area. The vacuum pump according to claim 1,
The vacuum pump is characterized in that the changing mechanism is configured such that the opening area of the opening side of the opening / closing valve of the discharge port is larger in the high rotation range than in the low rotation range. In the vacuum pump according to claim 1 or 2,
The change mechanism includes a moving member that moves into and out of an area on the opening side of the opening / closing valve of the discharge port by hydraulic pressure, and the opening / closing of the discharge port of the moving member is higher in the high rotation range than in the low rotation range. A vacuum pump characterized by being configured to reduce the amount of protrusion into the open side region of the valve. In the vacuum pump according to claim 1, claim 2, or claim 3,
The vacuum pump according to claim 1, wherein the on-off valve is configured as a reed valve including a leaf spring that covers the discharge port.

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