JP2007270698A - Variable displacement vane pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable displacement vane pump wherein variation in internal pressure in a pumping chamber in the transition section from a suction stroke to a discharge stroke is optimized without depending upon operation conditions to reduce vibration and noises. <P>SOLUTION: In the variable displacement pump, notches 40 are made in the vanes 10 and the sliding surface of a pressure plate 12. By taking advantage of differences in the amount of projection of the vanes 10 in accordance with the number of rotations, the vane pump is constituted so that at the time of a small number of rotations, the end of a suction port 14 or a discharge port 15 is not allowed to communicate with the notches 40, while as the number of rotations is increased, the continuous area is gradually expanded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, a rotor to which driving torque is input via a shaft, a cam ring eccentric to the rotor and a vane slidable in the radial direction of the rotor inside the cam ring are arranged. The present invention relates to a variable displacement vane pump that reduces the amount of eccentricity of the cam ring as it increases, thereby reducing the amount of discharge per revolution and keeping the discharge flow rate within a certain range regardless of the number of revolutions.

  In many cases, the vibration and noise during operation of the vane pump are problematic, and the configuration of the vane pump aiming at the reduction of such vibration and noise has been conventionally made. In particular, the pump chamber pressure suddenly changes from the suction pressure to the discharge pressure, or from the discharge pressure to the suction pressure at the switching portion between the suction stroke where the pump chamber volume increases between adjacent vanes and the discharge stroke where the volume decreases. In order to prevent the pump chamber from fluctuating, a transition section is provided in which the pump chamber does not open to either the suction port or the discharge port, and a process for pre-compressing or pre-expanding the pump chamber pressure by adjusting the inner diameter of the cam ring in the transition section is provided. ing. However, since the required degree of pre-compression or pre-expansion varies depending on the pump discharge pressure and the rotational speed, it is difficult to smoothly change the pump chamber pressure under any conditions. For this reason, a notch formed in a substantially V-shaped notch is provided at the start end of the discharge port or the suction port so that oil gradually flows into the pump chamber from the discharge port or gradually leaks from the pump chamber to the suction port. However, the effect is not sufficient.

  In view of such circumstances, in Japanese Patent Application Laid-Open No. 11-303773, the area where the notch is hidden changes as the cam ring swings, and the communication timing or communication between the notch and the pump chamber is changed from low speed rotation to high speed rotation. A technique is disclosed in which the shape or position of the notch is adjusted so as to optimize the area. In Japanese Patent Laid-Open No. 2000-110740, in order to correct that the timing at which pre-compression and pre-expansion occur due to an increase in the rotation speed is delayed, the opening timing of the suction port and the discharge port is delayed with the swing of the cam ring. Technology is disclosed.

JP-A-11-303773 JP 2000-110740 A

  As described in the background art above, the optimum degree of pre-compression or pre-expansion in the transition section varies depending on the pump discharge pressure and the rotational speed. In particular, there is a trade-off between low pressure and high rotation conditions and high pressure and low rotation conditions, which causes pump noise. This is because the difference between the suction pressure and the discharge pressure is high at high pressure, and there are many leaks in the transition section at low rotation, so it is necessary to increase the degree of pre-compression and pre-expansion, while low pressure and high rotation. This is because the pre-compression and the pre-expansion are excessive because the differential pressure and leakage are small under the above conditions, and the fluctuation of the pump chamber pressure is excessively increased. In order to improve this problem, the lengths of the pre-compression section and the pre-expansion section need to be longer during low speed rotation and shorter during high speed rotation.

  In order to realize this using the technique disclosed in Japanese Patent Application Laid-Open No. 11-303773, it is preferable to apply in the transition section from the discharge stroke to the suction stroke, that is, the pre-expansion stroke. This is because if the amount of eccentricity between the cam ring and the rotor decreases as the rotational speed increases, the area where the notch provided at the start end of the intake port is covered by the cam ring decreases, and the start timing of the intake stroke can be advanced. On the other hand, in the pre-compression stroke in which the pump chamber is switched from the suction stroke to the discharge stroke, if the amount of eccentricity decreases, the area covered by the notch with the cam ring increases, and thus the above-described effect cannot be obtained. For this reason, there was a possibility that the trade-off could not be eliminated in the pre-compression stroke.

  An object of the present invention is to provide a variable displacement vane pump that is provided with a mechanism that lengthens the lengths of the precompression section and the preexpansion section at a low rotation speed and shortens the length at a high rotation speed to reduce vibration and noise.

  In the first method, a cam groove having one end connected to the suction port is provided on the cam ring sliding surface, and the cam ring swings as the number of rotations increases, so that the cam groove and the precompression stroke pump chamber are provided. A notch is communicated, and a mechanism is provided to release the pressure increase at the beginning of the precompression stroke to the suction port.

  The second method utilizes the fact that a notch is provided on the sliding surface of the vane, and the radial position of the vane notch and the position of the end of the discharge port are relatively displaced by the swing of the cam ring. When the cam ring swings as the rotational speed increases, the notch or terminal portion of the intake port or discharge port start end and the vane notch communicate with each other, reducing the length of the pre-compression stroke or pre-expansion stroke. ing.

  The present invention eliminates the trade-off that the length of the optimal precompression stroke or pre-expansion stroke differs between the high pressure and low rotation conditions and the low pressure and high rotation conditions, and has the effect of reducing pump vibration and noise.

  Hereinafter, an embodiment in which the present invention is applied as a hydraulic pressure generation source of a power steering apparatus will be described with reference to the drawings.

  FIG. 1 is a front view in which a partial section is taken as an embodiment of a variable displacement vane pump according to the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. 2 is a cross-sectional view taken along the line BB in FIG. In FIG. 2, 1 is a front body constituting the main body, and 2 is a rear cover. A shaft 4 is supported on the front body 1 via a bearing 3, and the shaft 4 inputs a rotational driving force of an engine or the like (not shown) to the rotor 5. In FIG. 1, an adapter 6 is fitted in the front body 1, and a cam ring 7 is arranged with its center eccentric from the rotor 5. The cam ring 7 can roll inside the adapter 6 with the support pin 8 as the center. When the number of rotations increases, the cam ring 7 swings to the right in the drawing to reduce the eccentric amount, thereby reducing the discharge amount per rotation and the entire pump. A mechanism for keeping the discharge flow rate constant. The rotor 5 is provided with a plurality of slit-like vane grooves 9, and a plurality of vanes 10 are held so as to be slidable in the radial direction. A region surrounded by two adjacent vanes 10, the rotor 5, and the cam ring 7 constitutes a pump chamber 16, and the pumping action of suction and discharge is performed by increasing or decreasing the volume. A vane back pressure chamber 11 for pressing the vane 10 against the cam ring 7 is provided at the end of the plurality of vane grooves 9 close to the shaft 4, and the vane back pressure through the back pressure groove 13 formed in the pressure plate 12 in FIG. A discharge pressure is introduced into the chamber 11. The back pressure groove 13 is the same as that indicated by the dotted line in FIG. 1, and is connected to the individual vane back pressure chambers 11 by surrounding the ring. Since the back pressure groove 13 communicates with the pump discharge side pressure chamber 22 as shown in FIG. 2, the discharge pressure is applied to each vane back pressure chamber 11.

Above the adapter 6, a spool valve 32 for controlling the swinging displacement of the cam ring 7 is provided. A pump discharge side passage 26 is connected to the left chamber 28 of the spool valve 32 via a damper orifice 27, and its upstream side is connected to the pump discharge side pressure chamber 22. For this reason, the valve left chamber 28 is filled with oil of discharge pressure. On the other hand, the right chamber 29 of the spool valve 32 is connected to the right fluid pressure chamber 24, which is a region sandwiched between the right side of the cam ring 7 and the adapter 6, via the passage 35, and from there to the downstream side of the metering orifice The hydraulic pressure is supplied to the power steering device and the like through the passage 30 and the discharge side pipe joint 36. Since the oil discharged from the pump discharge side pressure chamber 22 passes through the metering orifice 25 and is guided to the right fluid pressure chamber 24, the pressure in the right fluid pressure chamber 24 and the valve right chamber 29 is the pump discharge side pressure. It becomes lower than the pressure in the chamber 22. The pressure drop at the metering orifice 25 varies depending on the discharge flow rate, and the larger the flow rate, the larger the pressure difference generated between the left and right sides of the spool valve 32. That is, since the flow rate passing through the metering orifice 25 is small when the pump rotational speed is low, such as when idling, the left-right pressure difference of the spool valve 32 is small, and the spool valve 32 is pressed to the left side wall. However, when the rotational speed increases, the pressure in the valve right chamber 29 decreases, the spool valve 32 is displaced in the right direction, and a part of the oil filling the valve left chamber 28 through the passage 33 to the left fluid pressure chamber 23. And the pressure in the left fluid pressure chamber 23 is increased. As a result, the cam ring swings in the right direction as the pump speed increases.

  Next, details of the pump action will be described. Here, in FIG. 1, the rotor is assumed to rotate counterclockwise. In the suction stroke in which the pump chamber 16 is open to the suction port 14, the volume of the pump chamber 16 increases, so that oil is sucked from the suction port 14. On the other hand, in the discharge stroke in which the pump chamber 16 is open to the discharge port 15, the volume of the pump chamber 16 decreases, so that oil is discharged from the discharge port 15. The oil discharged from the discharge port 15 is discharged out of the pump via the pump discharge side pressure chamber 22 shown in FIG. In the switching section from the suction stroke to the discharge stroke, or in the switching section from the discharge stroke to the suction stroke, pressure fluctuations and back flow phenomenon caused by a sudden change in the internal pressure of the pump chamber 16 occur, causing vibration or noise. Become. Therefore, in the switching section, a transition section is provided in which the pump chamber 16 does not open to either the suction port or the discharge port, and a process for adjusting the inner diameter of the cam ring 7 in the transition section and pre-compressing or pre-expanding the pump chamber 16 internal pressure is provided. ing.

  A pre-compression stroke X indicated by an arrow in FIG. 1 is a transition section from the suction stroke to the discharge stroke, and the pump chamber 16 is not opened in either the suction port 14 or the discharge port 15. In the pre-compression stroke X, the pressure is increased by adjusting the volume of the pump chamber 16 to gradually decrease, and the internal pressure of the pump chamber 16 plays a role of smoothly increasing from the suction pressure to the discharge pressure. However, the optimal pressure increase, that is, the length of the pre-compression stroke, is different when the pump discharge pressure is low and high, so the length of the pre-compression stroke is adjusted so that it can be used under all conditions from low pressure to high pressure. As a result, pre-compression tends to be excessive under low pressure conditions, and conversely, pre-compression tends to be insufficient under high pressure conditions. In either case, a differential pressure is generated between the internal pressure of the pump chamber 16 and the discharge pressure, which causes noise due to pressure fluctuation when the pump chamber 16 opens to the discharge port 15. This is remarkable in the condition of rotation. This is because the pressure is likely to rise more at high rotations because there is little leakage in the pre-compression stroke, and the pressure is difficult to rise because there are many leaks at low rotations. In order to alleviate the pressure fluctuation caused by the tradeoff in the length of the precompression stroke between the high pressure and the low pressure as described above, it is generally performed to provide the notch 37 at the start end of the discharge port 15, but the effect is Not enough. As for the transition section from the discharge stroke to the suction stroke, a pre-expansion stroke Y is provided as shown in FIG. 1, and the internal pressure of the pump chamber 16 is lowered from the discharge pressure to the suction pressure and then opened to the suction port 14. . Again, since there is a trade-off in the length of the precompression stroke, the pressure fluctuation is reduced by providing the notch 41, but the effect is not sufficient.

In this embodiment, in order to eliminate this trade-off, the low pre-rotation speed increases the precompression stroke by increasing the communication end timing of the pump chamber 16 and the suction port 14, and the high rotation speed delays the communication end timing. A mechanism for shortening the pre-compression stroke is realized as follows. As shown in FIG. 3, a cam groove 38 is provided on the sliding surface of the cam ring 7 with the pressure plate 12, and a communication notch 39 is provided on the side of the pressure plate 12 facing the pump chamber 16. One end of the cam groove 38 communicates with the suction port 14, and oil is always guided from the suction port 14 to the cam groove 38. During low rotation such as idling, the cam ring 7 is at the maximum eccentric position (left in FIG. 3), and the cam groove 38 and the communication notch 39 are not in contact with each other. However, as the rotational speed increases, the cam ring 7 swings rightward, and the cam groove 38 and the communication notch 39 communicate with each other at a certain rotational speed (FIG. 3 right). Thus, the pump chamber 16 opens to the suction port 14 until the rear vane 10 passes the position of the communication notch 39. For this reason, the pressure increase at the beginning of the precompression stroke can be released, and the start timing of the precompression stroke can be delayed. At this rotational speed, the cam groove 38 and the communication notch 39 are barely connected, so the effect of releasing the pre-compression due to the communication is small, but the communication area of the cam groove 38 and the communication notch 39 as the cam ring 7 further swings in the right direction. The degree of pre-compression can be reduced. The rotational speed at which the communication is started can be changed by adjusting the arrangement of the cam groove 38 and the communication notch 39 according to the generation speed of the noise that causes the problem, and the pre-compression stroke X is low and long and high. The variable notch mechanism is configured to be shorter.

  FIG. 4 shows the characteristics of the variable displacement vane pump provided with such a variable notch mechanism in comparison with the cam ring 7 swing angle in the transition of the rotational speed. As the rotational speed increases, the swing angle increases and the pump discharge flow rate per rotation decreases. As a result, the discharge flow rate of the entire pump is kept within a certain range. On the other hand, when the rotation speed exceeds a certain value, the cam groove 38 and the communication notch 39 start to communicate, and the communication area increases as the rotation speed increases. For example, if the noise generation speed at high pressure and low rotation is 900 rpm and the noise generation speed at low pressure and high rotation is 2000 rpm, the pre-compression stroke X is lengthened and the communication is started at about 1500 rpm. In addition, it is possible to reduce noise due to a trade-off between insufficient precompression at high pressure and low rotation and excessive precompression at low pressure and high rotation.

  As a method of satisfying the required specification of lengthening the precompression section on the low rotation side and shortening on the high rotation side, a method of providing a notch in the vane as follows can be considered. FIG. 5 shows an enlarged view of the pump chamber in the vicinity of the pre-compression section X in FIG. 1 and compares the difference between the low-speed rotation side and the high-speed rotation side. In this embodiment, a notch 40 is provided on the sliding surface with the pressure plate 12 on the rear side of the vane 10 with respect to the rotation direction (counterclockwise). The notch 40 is provided at a position that does not overlap with the discharge-side notch 37 when idling, but the notch 40 and the notch 37 overlap with each other because the vane 10 is pushed toward the center of the rotor 5 at high rotation, and the discharge port 15 Advance opening timing. Further, in order to prevent mistakes when assembling the vanes, a similar notch 40a is provided on the sliding surface with the rear cover 2 at a point symmetrical with the notch 40.

  In order to change the length of the precompression section, a method of changing the opening end timing to the suction port 14 of the pump chamber 16 may be used. FIG. 6 shows a case where a notch 40b is provided on the front side of the vane 10 with respect to the rotational direction, and the opening end timing of the suction port is changed. The notch 40b is provided at a position where it does not overlap with the suction port 14 during idling, but the vane 10 is pushed toward the center of the rotor 5 during high speed rotation, so the notch 40b and the suction port 14 overlap, and the end timing of the suction stroke Delay. Also in this case, in order to prevent an error in assembling the vane, a similar notch 40c is provided on the sliding surface with the rear cover 2 at a position symmetrical to the notch 40b.

  Regarding the pre-expansion section, the length of the pre-expansion section should be increased on the low rotation side and shortened on the high rotation side, and a mechanism for changing the opening timing to the suction port 14 is provided as shown in FIG. By providing the notch 40d on the rear side of the vane 10 with respect to the rotation direction, the notch 40d does not overlap the suction side notch 41 during idling, but the portion where the vane 10 protrudes from the rotor 5 increases during high-speed rotation. 40d and the suction side notch 41 overlap, and the opening timing to the suction port 14 is advanced. In order to prevent erroneous assembly, the notches 40e may also be provided point-symmetrically. Further, as in FIG. 6, a notch may be provided to change the opening end timing to the discharge port 15.

  In the above examples, all types of notches may be provided in all the vanes, or only one of them may be provided. Different types of notches may be provided in the individual vanes to shift the suction and discharge timing phases between the pump chambers, thereby reducing the noise of the rotational order component. Furthermore, since the notches 40 and 40d are provided at the same position at the tip of the vane 10, the shapes of the discharge-side notch 37 and the suction-side notch 41 are adjusted so that the notches 40 and 40d can be used in common. Good.

The front view which carried out one section which shows one example of the vane pump of the present invention. Sectional drawing seen from the bottom face which shows one Example of the vane pump of this invention. The figure which compared the effect by one Example of this invention at the time of low speed rotation and high speed rotation. The figure which represented the characteristic of the pump in one Example of this invention by the rotation speed change. The figure which compared one Example which applied this invention to the discharge port start end at the time of low speed rotation and high speed rotation. The figure which compared one Example which applied this invention to the suction port termination | terminus at the time of low speed rotation and high speed rotation. The figure which compared one Example which applied this invention to the suction port start end at the time of low speed rotation and high speed rotation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Front body, 2 ... Rear cover, 3 ... Bearing, 4 ... Shaft, 5 ... Rotor, 6 ... Adapter, 7 ... Cam ring, 8 ... Support pin, 9 ... Vane groove, 10 ... Vane, 11 ... Vane back pressure chamber, DESCRIPTION OF SYMBOLS 12 ... Pressure plate, 13 ... Back pressure groove, 14 ... Suction port, 15 ... Discharge port, 16 ... Pump chamber, 22 ... Pump discharge side pressure chamber, 24 ... Right fluid pressure chamber, 25 ... Metering orifice, 26 ... Pump discharge side passage, 27 ... damper orifice, 28 ... valve left chamber, 29 ... valve right chamber, 30 ... metering orifice downstream passage, 32 ... spool valve, 33, 35 ... passage, 36 ... discharge side pipe joint 37 ... Discharge side notch, 38 ... Cam groove, 39 ... Communication notch, 40 ... Notch, 41 ... Suction side notch.

Claims (7)

A rotor that is rotationally driven by a shaft and a cam ring are arranged eccentrically so that the vanes can enter and exit in a radial direction while sliding from a plurality of vane grooves provided in the rotor, and the pump is divided by side plates and adjacent vanes The transition section between the suction stroke in which the volume of the chamber increases and the discharge stroke in which the volume decreases is connected by a transition stroke in which the pump chamber does not open to either the suction port or the discharge port. A notch formed in a notch shape was provided, and the cam ring oscillated with an increase in the number of rotations to reduce the amount of eccentricity, lower the discharge amount per rotation, and keep the overall discharge flow rate within a certain range. In variable displacement vane pumps,
A groove-shaped notch is provided on the side plate, and a concave passage is provided on the sliding surface of the cam ring with the side plate. The groove shape is formed on the side plate or the cam ring so that the concave passage communicates with the suction port. The variable displacement vane pump, wherein the notch provided in the side plate and the recessed passage provided in the cam ring communicate with each other as the amount of eccentricity of the cam ring decreases as the rotational speed increases. A rotor that is rotationally driven by a shaft and a cam ring are arranged eccentrically so that the vanes can enter and exit in a radial direction while sliding from a plurality of vane grooves provided in the rotor, and the pump is divided by side plates and adjacent vanes The transition section between the suction stroke in which the volume of the chamber increases and the discharge stroke in which the volume decreases is connected by a transition stroke in which the pump chamber does not open to either the suction port or the discharge port. A notch formed in a notch shape was provided, and the cam ring oscillated with an increase in the number of rotations to reduce the amount of eccentricity, lower the discharge amount per rotation, and keep the overall discharge flow rate within a certain range. In variable displacement vane pumps,
The configuration is such that the communication timing or communication area between the port end or the substantially V-shaped notch provided therein and the pump chamber is changed by a notch provided in a vane that enters and exits the rotor as the cam ring swings. A variable displacement vane pump characterized by The variable displacement vane pump according to claim 2,
A variable displacement vane pump characterized in that when the cam ring swings, the communication timing of the notch or the port end is advanced by the notch of the vane to enlarge the communication path. The variable displacement vane pump according to claim 2,
When the notch or the port end where the communication timing or the communication area is desired to be variable is at the start end of the suction port or the discharge port with respect to the vane rotation progression direction, the vane notch is located on the reverse side of the vane progression direction plate thickness. A variable displacement vane pump characterized by being provided on the forward side of the thickness in the vane traveling direction when provided and at the end. The variable displacement vane pump according to any one of claims 2 to 4,
The pressure chamber side of the pressure rise from the suction port to the discharge port is characterized in that a vane notch is provided on the cam ring side at the height of the vane in / out direction from the contact position between the port end or notch end and the vane at the maximum eccentricity. Variable displacement vane pump. The variable displacement vane pump according to any one of claims 2 to 4,
On the pressure chamber side of the pressure drop from the discharge port to the suction port, a vane notch is provided on the rotor side at the height of the vane in / out direction from the contact position between the port end or notch end at the time of maximum eccentricity and the vane. Variable displacement vane pump. The variable displacement vane pump according to any one of claims 2 to 6,
A variable displacement vane pump characterized in that the notch of the vane is provided rotationally symmetrically with the vane in / out direction as an axis.

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