The present application is related and has right of priority to WO Publication No. 2019/121188 filed on Dec. 12, 2018 and to German Patent Application No. 10 2017 223 530.6 filed on Dec. 21, 2017, which are both incorporated by reference in their entirety for all purposes.
The invention generally relates to a vane pump and to a method for operating this vane pump.
The vanes of a vane pump, which are radially movable in the guide slots of the rotor, must be pressed, during operation, by a certain minimum contact pressure with their vane outer side against the cam ring, in order to reliably seal the working chambers formed between the vanes. In principle, the vanes are pressed, during operation, by the centrifugal force radially outward against the cam ring.
In order to ensure the necessary contact pressure also at low speeds—and, therefore, low centrifugal forces onto the vanes—it is known that vane pumps have a so-called behind-vane pressurization. In this case, a behind-vane pressure is applied onto the radially inward-facing side of a vane, which is referred to in the following as the vane inner side, so that the vane is pressed outward against the cam ring. As a result, it is ensured that the vanes rest securely against the cam ring via their vane outer side also at low rotational speeds. This has positive effects on the suction behavior as well as on the volumetric efficiency of the vane pump, in particular in the low rotational speed range. A behind-vane pressurization can be utilized in the case of vane pumps having a variable displacement volume as well as having a fixed displacement volume.
Such a behind-vane pressurization is known from DE 19546329 A1, which describes a double-stroke vane pump having a fixed displacement volume. This double-stroke vane pump includes a control plate and a pressure plate, which delimit the vane pump in the axial direction. Pressure is applied to so-called behind-vane spaces through annular ducts connected to the pressure side of the vane pump, which are designed as circular-ring-sector-shaped cavities in the pressure and control plate concentrically to the axis of rotation of the rotor and within the outer diameter of the rotor. As a result, the vanes are pressed radially outward against the cam ring. The annular ducts are also referred to in the following as behind-vane pressure ducts.
A behind-vane space is the radially internal portion of a guide slot in the rotor of a vane pump, wherein the behind-vane space is delimited radially outward by a vane inner side of the vane. The behind-vane space is axially delimited by the control plate and the pressure plate. The pressure that prevails in the behind-vane spaces is also referred to as behind-vane pressure. The behind-vane pressure acts upon the surface of the vane inner side, as the operative pressure surface, in a radial projection and, as a result, generates a radially outward directed force onto the vanes. In this case, the vane pump includes a suction-side behind-vane pressure duct and a pressure-side behind-vane pressure duct. The suction-side behind-vane pressure duct extends across the angular range of the vane pump, in which the working chambers between the vanes enlarge during a rotation of the rotor, so that the operating medium (usually transmission oil) to be conveyed is sucked in. This angular range is therefore also referred to as the suction region. The vanes move outward in the guide slots, so that the behind-vane spaces enlarge.
The pressure-side behind-vane pressure duct extends across the angular range of the vane pump, in which the working chambers between the vanes become smaller during a rotation of the rotor, so that the conveyed operating medium is displaced. This angular range is also referred to in the following as the displacement region. During a rotation of the rotor through the displacement region, the vanes move radially inward in the guide slots, and so the behind-vane spaces become smaller and the operating medium is displaced from the behind-vane spaces into the pressure-side behind-vane pressure duct.
The suction-side behind-vane pressure duct and the pressure-side behind-vane pressure duct are connected to each other via constrictions. These constrictions operate as hydraulic resistors and can be designed, for example, as throttle points or throttle valves or orifices. Usually, the suction-side behind-vane pressure duct is connected to the pressure side of the vane pump and is therefore acted upon by a pressure, which is referred to in the following as pump pressure.
The mode of operation of this arrangement is as follows. In the displacement region, the pump pressure acts upon the vane outer sides and presses these radially inward, counter to the centrifugal force. In order to hold the vane outer sides securely against the cam ring, the behind-vane pressure in the pressure-side behind-vane pressure duct must be greater than the pump pressure that prevails in the displacement region in the working chambers of the vane pump. This can be achieved with the aid of the arrangement, described in the following, of the hydraulic resistances between the suction-side behind-vane pressure duct and the pressure-side behind-vane pressure duct as well as the connection of the suction-side behind-vane pressure duct to the pressure side of the vane pump. During the turning motion of the rotor of the vane pump, the vanes are pressed, as described, against the cam ring via the vane outer side due to the centrifugal force and the behind-vane pressure and glide along the cam ring, and so the vanes necessarily carry out a reciprocating motion in the slot throughout one revolution. The pump pressure acts, via a hydraulic connection, in the suction-side behind-vane pressure duct and, via a constriction, also in the pressure-side behind-vane pressure duct. In the suction-side behind-vane pressure duct, the suction-side behind-vane pressure corresponding to the pump pressure reliably presses the vanes against the cam ring, so that a reliable suctioning of the vane pump is ensured. If the behind-vane spaces reach the end of the suction region or the end of the suction-side behind-vane pressure duct, the volume of the particular behind-vane space is the maximum due to the travel of the particular vane and is acted upon by the pump pressure.
During the further rotor rotation through the now adjoining displacement region, the vanes are pushed radially inward, so that the volume of the particular behind-vane space is reduced and the operating medium is displaced from the behind-vane space as described above. Therefore, the operating medium in the behind-vane spaces is conveyed from the suction region to the pressure or displacement region. The relative forces on a vane are as follows. The centrifugal force occurring during a rotation of the rotor and the force from the behind-vane pressure, which acts upon the vane inner side, act radially outward. Counteracting this is the force from the pump pressure, which acts upon the vane outer side. Since the centrifugal force decreases with the rotational speed, the pressure-side behind-vane pressure must be greater than the pump pressure.
Due to the hydraulic resistances, the operating medium displaced from the behind-vane spaces can now flow, not unobstructed, from the pressure-side behind-vane pressure duct to the suction-side behind-vane pressure duct. As a result, the behind-vane pressure in the pressure-side behind-vane pressure duct increases beyond the pump pressure, so that the vane outer sides reliably rest against the cam ring in the pressure region as well. If the pressure-side behind-vane pressure duct would be directly connected to the pressure region of the vane pump, only the pump pressure would prevail in the behind-vane pressure duct, whereby the pressures on the vane outer side and the vane inner side would be equal and the vane outer sides in the displacement region would not unambiguously rest against the cam ring.
The level of the hydraulic resistance (restrictor or orifice) is determined, for example, on the basis of the flow cross-section or on the basis of a resistance coefficient or on the basis of a pressure differential between the pressure upstream from and downstream from the hydraulic resistance. This pressure differential is also referred to in the following as pressure loss. Due to the behind-vane pressure increasing with the hydraulic resistance, the vane outer sides are pressed counter to the pump pressure in the working chambers of the vane pump against the cam ring, and so these achieve an appropriate sealing effect. As a result, frictional forces naturally arise between the cam ring and the vane outer side, which generate a torque loss and, therefore, a power loss, but are unavoidable for the reliable function of the vane pump.
With respect to the configuration of the hydraulic resistance, the hydraulic resistance is selected in such a way that the pressure-side behind-vane pressure at a certain rotational speed suffices, on the one hand, for securely sealing the working chambers and, on the other hand, does not considerably exceed this value, and so the frictional forces arising due to the contract pressure of the vanes are held within limits. The certain rotational speed is preferably in the lower rotational speed range in this case, since the centrifugal forces are lowest here.
As the rotational speed increases, the flow conveyed through the behind-vane spaces increases and, therefore (according to the equation for a flow through a hydraulic resistance), the behind-vane pressure in the pressure-side behind-vane pressure duct increases. As a result, the radial force between the vane outer side and the cam ring exceeds the force necessary for the secure seal, whereby, disadvantageously, the power loss increases and the efficiency of the pump deteriorates. Further possible undesirable effects due to an excessive contact pressure and/or an excessive behind-vane pressure are wear on the cam ring and the vane outer side as well as noise.
An increasing viscosity of the operating medium at low temperatures also results in an undesirable increase of the behind-vane pressure. As the viscosity of the oil increases, so does the hydraulic resistance and/or the pressure loss at the throttle point. As a result, a higher pressure arises in the pressure-side behind-vane pressure duct than is the case at a normal operating temperature, whereby the contact force of the vane onto the cam ring and the drive torque of the vane pump increase and adversely affect efficiency and service life in a disadvantageous way.
Example aspects of the present invention provide a vane pump, in the case of which a reliable seal prevails between the vanes and the cam ring across preferably all operating ranges, without worsening the overall efficiency and the wear behavior of the vane pump. In particular, the pressure-side behind-vane pressure should be limited below a reliable maximum value, in order to reduce these negative effects on efficiency and wear behavior.
In example embodiments, this object is achieved due to the fact that a vane pump for an automatic transmission includes a suction-side behind-vane pressure duct and a pressure-side behind-vane pressure duct. The suction-side behind-vane pressure duct is connected to the pressure side of the vane pump, so that the pump pressure prevails therein. According to example aspects of the invention, the vane pump includes a valve unit, to which the pressure-side behind-vane pressure duct is connected, wherein, during operation of the vane pump, the level of a pressure-side behind-vane pressure in the pressure-side behind-vane pressure duct is adjustable with the aid of the valve unit.
The term “adjustable” is to be understood to mean, in this context, that the pressure-side behind-vane pressure can be set at a constant or variable value with the aid of the valve unit.
In one preferred example embodiment of the invention, the valve unit is arranged between the pressure-side behind-vane pressure duct and the suction-side behind-vane pressure duct, so that the pressure-side behind-vane pressure duct can be connected to the suction-side behind-vane pressure duct with the aid of the valve unit. As a result, the valve unit can be arranged with the least amount of required installation space. It is also possible to lower the pressure-side behind-vane pressure to the level of the pump pressure by reducing the hydraulic resistance of the valve unit to zero. The pressure-side behind-vane pressure then corresponds to the suction-side behind-vane pressure and, therefore, to the pump pressure.
The hydraulic resistance of the valve unit is understood to mean the pressure losses during the through-flow of the valve unit in an example embodiment as a throttle valve or as an orifice, and as an opening pressure in an example embodiment as a pressure limiting valve.
It is also possible that the suction-side behind-vane pressure duct is connectable, via a valve unit, not only to the suction-side behind-vane pressure duct but also to another region of the hydraulic system, such as a non-pressurized region. As a result, it is possible, for example, to reduce the pressure-side behind-vane pressure to zero, due to the fact that the pressure-side behind-vane pressure duct is connected to the non-pressurized region if the centrifugal force of the vanes suffices, without an additional hydraulic pressure, to press the vane ends, counter to the pump pressure, against the cam ring and, thereby, to ensure a reliable function of the vane pump.
In one further example embodiment, the pressure-side behind-vane pressure duct can be connected, via a valve unit having a variable resistance, to the pressure port or to the pressure side of the vane pump.
In addition, several valve units can be arranged between various regions of the pressure-side behind-vane pressure duct and the suction-side behind-vane pressure duct, so that more flow cross-section is available and the pressure-side behind-vane pressure can be changed faster.
It can also be provided that the valve unit is arranged between the pressure-side behind-vane pressure duct and a region of the suction side of the vane pump.
Advantageously, the valve unit has a variable hydraulic resistance. Due to the change of the resistance, the flow flowing through the valve unit from the pressure-side behind-vane pressure duct to the suction-side behind-vane pressure duct and, therefore, the pressure-side behind-vane pressure, can be changed.
Preferably, the valve unit is designed as an adjustable throttle valve or as an adjustable orifice.
Alternatively, the valve unit is designed as an adjustable orifice.
As a further alternative, the valve unit is designed as a pressure limiting valve, through which flow can take place from the pressure-side behind-vane pressure duct to the suction-side behind-vane pressure duct.
If multiple valve units should be arranged in the vane pump, these can be identically or differently designed, as restrictors, orifices, or pressure limiting valves.
In one preferred example embodiment of the invention, it is provided that the hydraulic resistance of the valve unit is adjustable with the aid of an electronic transmission control unit depending on one or multiple operating variables. The operating variables, which are detected in the electronic transmission control unit, are physical values, which indicate the operating condition of the vane pump, such as the temperature of the operating medium, the pump speed, or the pressure in the pressure-side behind-vane pressure duct.
Currents of the electronic transmission control unit can also be detected, which indicate a pump pressure generated by the pump.
It is possible that the vane pump includes a sensor unit, which detects the pressure-side behind-vane pressure.
Advantageously, the change of the pressure-side behind-vane pressure takes place depending on different operating parameters, which are detected in the electronic transmission control unit.
In addition, it is possible that the pressure-side behind-vane pressure is reduced after a start signal of the vane pump after a certain time period has lapsed. This time period, after the lapse of which it is known that the pressure-side behind-vane pressure no longer must be raised to a maximum value and can now be lowered, can be experimentally determined in advance.
It can also be provided that the hydraulic resistance of the valve unit is adjustable with the aid of an actuator.
In a further alternative or additionally usable example embodiment of the invention, the valve unit is designed as an automatically, temperature-dependently variable restrictor or orifice, wherein the hydraulic resistance thereof is greater at low temperatures than at higher temperatures, so that the pressure-side behind-vane pressure is greater at lower temperatures than at higher temperatures. The automatically, temperature-dependently variable restrictor or orifice can have its effect due to the utilization of a memory metal or a bimetal. The advantage of this example embodiment is an increase of the pressure-side behind-vane pressure for the critical cold start phase, in which it must be ensured that the vanes securely rest against the cam ring.
In a preferred example embodiment of the vane pump, axially and/or radially directed ducts are formed in an axial plate of the vane pump, which connect the pressure- and suction-side behind-vane pressure ducts to the valve unit.
One advantageous example embodiment provides that the pressure-side behind-vane pressure duct and the suction-side behind-vane pressure duct are hydraulically connected to each other, wherein a hydraulic resistance is formed between the pressure-side behind-vane pressure duct and the suction-side behind-vane pressure duct. In addition, a pressure limiting valve is arranged between the pressure-side behind-vane pressure duct and the pressure duct or the pressure side of the vane pump. The pressure limiting valve is arranged in such a way, in this case, that flow therethrough can take place from the pressure-side behind-vane pressure duct, so that the pressure-side behind-vane pressure can be limited with the aid of the pressure limiting valve. Alternatively, the pressure-side behind-vane pressure duct can be connectable via the pressure limiting valve to a suction duct of the vane pump or to a non-pressurized region of the automatic transmission.
Preferably, the hydraulic resistance can be designed as a restrictor or as an orifice.
It is possible that the vane pump is designed as a single-flow (or also referred to as single-stroke) or multi-flow (also referred to as multi-stroke) vane pump. In the case of a single-stroke vane pump, the rotor is arranged eccentrically with respect to a circular cam ring, so that the vanes implement one complete stroke through one revolution of the rotor, i.e., the vanes are located at their radial innermost position one time and at their radially outermost position one time per revolution. In the case of a two-stroke vane pump, the vanes are located at their radial innermost position two times and at their radially outermost position two times during one revolution of the rotor. Since a single-stroke vane pump includes only one suction connection and one pressure connection, this is also referred to as single-flow. A two-stroke vane pump, however, includes two self-sufficient delivery units, which, theoretically, can supply two separate consumers with different pressures or flow rates. A two-stroke vane pump therefore also includes two suction and pressure connections, which is why this is also referred to as a double-flow vane pump.
A single-stroke vane pump generally includes only one suction-side behind-vane pressure duct and one pressure-side behind-vane pressure duct. A two-stroke vane pump generally includes two pressure-side and two suction-side behind-vane pressure ducts, which are respectively connected to each other by valve units as described above.
A method is provided for operating an above-described vane pump, in which an actual value of the pressure-side behind-vane pressure and certain operating parameters are detected and the actual value is compared to a specified value of the behind-vane pressure associated with the operating parameters, wherein, in the case of a deviation of the actual value from the specified value, the pressure-side behind-vane pressure is adapted to the specified value by changing the hydraulic resistance of the valve unit.
In so doing, it is provided that the actual value of the pressure-side behind-vane pressure is measured by a pressure sensor.
Alternatively, a method is provided for operating a vane pump, in which an actual value of at least one certain operating parameter is detected, which indirectly indicates the level of the pressure-side behind-vane pressure, after which this actual value is compared to a specified value associated with the operating parameters, wherein, in the case of a deviation of the actual value from the specified value, the pressure-side behind-vane pressure is adapted to the specified value by changing the hydraulic resistance of the valve unit until the actual value of the certain operating parameter matches its specified value.
A detected operating parameter can be the temperature of the pump or of the operating medium in this case, since, as a result, inferences can be drawn regarding whether a cold start is present, in which case a sufficient contract pressure of the vanes in the pressure region of the vane pump is to be ensured.
As a further alternative, during a cold start, the pressure-side behind-vane pressure can remain elevated for a certain time period and, after this time period, which has a duration determined via experimentation, can be lowered, so that the cold intake during a cold start is ensured and, thereafter, the friction of the vanes does not remain at an excessively high level to the detriment of the efficiency.
In one preferred example embodiment, it is provided that the vane pump includes a valve unit, with the aid of which, at least in a first operating condition, at least one behind-vane pressure duct can be hydraulically disconnected from the pressure region of the pump and at least one behind-vane pressure duct can be connected to a non-pressurized region, and, in a second operating condition, at least one behind-vane pressure duct can be connected to the pressure region of the vane pump.
It is also possible that the vane pump is designed to be at least two-stroke and, therefore, includes at least two pressure-side behind-vane pressure ducts and at least two suction-side behind-vane pressure ducts. The aforementioned example embodiments are then formed in each self-sufficient portion of a multi-stroke vane pump between suction-side and pressure-side regions. Suction-side and pressure-side regions encompass behind-vane pressure ducts, pressure ports and suction ports, as well as suction lines and pressure lines.
For a vane pump designed in such a way, a method is provided, in which, in a lower rotational speed range during or after the start of the vane pump, initially the pressure-side behind-vane pressure is raised with the aid of the valve unit while the suction-side behind-vane pressure duct is connected to the pressure side of the vane pump and the pressure-side behind-vane pressure duct is disconnected from a non-pressurized region. Once a second rotational speed or pressure value has been reached, the hydraulic resistance of the valve unit between the behind-vane pressure ducts is reduced, so that the pressure-side behind-vane pressure decreases. During a further rotational speed increase, once a third, highest rotational speed value has been reached, the behind-vane pressure ducts are disconnected from the pressure side of the vane pump and are connected to a non-pressurized region.
Additionally, in this method, in addition to the rotational speed of the vane pump, an operating temperature of the vane pump can also be detected in the electronic transmission control unit and, during a start of the vane pump at an operating temperature below a certain temperature, the resistance of the valve unit can be initially increased in such a way that the pressure-side behind-vane pressure increases above a certain pressure value, which has been selected to be sufficiently high in order to press the vane ends against the cam ring. As the rotational speed increases, the pressure-side behind-vane pressure is reduced with the aid of the valve unit.
Advantageously, an above-described vane pump is arranged in an automatic transmission for a motor vehicle.
Exemplary embodiments of the vane pump according to the invention are represented in the drawings and are described in greater detail in the following.
Wherein
Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.
The vane pump shown in
The pressure-side behind-vane pressure duct 11 and the suction-side behind-vane pressure duct 12 are connected to each other at their two ends by a throttle point 13 and 14, respectively. The throttle points 13 and 14 are also referred to as throttle valves. The throttle points 13 and 14 are hydraulic resistances or constrictions. These are utilized, as described above, in such a way that, during a displacement of the operating medium, generally transmission oil, during the radial retraction movement of the vanes 6 during movement over the pressure port, the pressure-side behind-vane pressure pDH increases, since, due to the pressure losses and/or the flow resistances in the throttle points 13 and 14, the oil cannot be displaced fast enough out of the pressure-side behind-vane pressure duct 11 into the suction-side behind-vane pressure duct 12. This has disadvantages, however, as described above, since, due to the resistances of the throttle valves 13 and 14, the pressure-side behind-vane pressure pDH increases beyond a reasonable extent during a higher speed and, therefore, a higher displacement speed of the operating medium.
For this purpose, the pressure-side behind-vane pressure pDH can be measured, for example, with the aid of a pressure sensor 141, which transmits the measured value via a signal line 145 to an electronic transmission control unit 140. In the electronic transmission control unit 140, a specified-actual value comparison is carried out and the resistance in the valve unit 113 or 114 is changed or reduced for as long as it takes for the specified value of the pressure-side behind-vane pressure pDH to be reached. The adjustable throttle valves 113 and 114 are actuated by the electronic transmission control unit 140 via signal lines 143 and 144, respectively. Theoretically, it would also be possible to provide only one valve unit between the behind-vane pressure ducts, although the maximum available flow cross-section would then be limited.
Alternatively or in addition to the measurement of the pressure-side behind-vane pressure pDH, an indication of the force ratios on the vanes or on the cam ring can be obtained by measuring a pump speed n, since the contact pressures increase as the rotational speed n increases and, thereby, the pressure-side behind-vane pressure pDH can be lowered. In addition, on the basis of an operating temperature T_Öl or a corresponding component temperature, it can be detected whether the vane pump is in a cold start phase, in which it is necessary for the vane ends to rest securely against the cam ring in order to suction the operating medium into the vane pump. During this cold start phase, the pressure-side behind-vane pressure pDH must be slightly greater than in the case of a subsequently reached higher rotational speed n and, therefore, greater centrifugal forces of the vanes onto the cam ring.
An enlargement of the flow cross-section of the throttle valve has a great effect on the level of the pressure-side behind-vane pressure pDH. For example, this is reduced by approximately 50% when the cross-sectional area of the restrictor is enlarged by 166%. The maximum pressure difference in tests was p=50 bar.
Theoretically, starting at a certain speed, the pressure-side behind-vane pressure duct as well as the suction-side behind-vane pressure duct can be closed toward the rest of the hydraulic system and connected to a non-pressurized region with the aid of a valve unit.
In principle, the valve units can be arranged on the side of only one axial plate or both axial plates; for reasons related to cost and installation space, however, only a one-sided embodiment is to be preferred, provided the implementable flow cross-sections are sufficient.
The purpose of these components, which are in addition to the example embodiment from
The pressure control valve 418 is completely opened in this case, whereby the pressure-side behind-vane pressure duct 411 is connected to a non-pressurized region 419, so that the pressure-side behind-vane pressure pDH corresponds to the ambient pressure, i.e., is practically non-pressurized. The throttle valves 413 and 414 are completely opened in this case, whereby the suction-side behind-vane pressure duct 412 is also connected to the non-pressurized region 419 and the pressure-side behind-vane pressure pSH is also non-pressurized. The shut-off valve 421 is closed at the point in time t3, in order to prevent a pressurization of the suction-side behind-vane pressure duct 412 by the pump pressure pP. Alternatively, the shut-off valve 421 can also be designed as a pressure control valve.
A line can be understood to mean any geometric configuration in which a liquid can be conducted from one point to another point. A line can be designed as a pipe line, a recess such as an indentation in the material of the pressure plate, as a bore hole or an arrangement of multiple bore holes, as a duct configured via casting, or as a combination of the aforementioned possibilities of a line.
The pressure limiting valve 513 is arranged in such a way, in this case, that flow therethrough can take place from the pressure-side behind-vane pressure duct 511 toward the pressure line 517 when the pressure-side behind-vane pressure pDH in the pressure-side behind-vane pressure duct 511 exceeds a certain value. As an alternative to the pressure limiting valve 513, a check valve can also be arranged at this point, wherein the check valve has the same pass-through direction as the pressure limiting valve 513.
The line 532 has a certain hydraulic resistance. This hydraulic resistance can be designed in the form of an orifice or, as represented in the exemplary embodiment, a restrictor 535. If, during the operation of the vane pump, the rotational speed now increases or if the viscosity of the operating medium increases at low temperatures, the pressure-side behind-vane pressure pDH excessively increases. At a maximally permissible pressure value, the pressure limiting valve 513 opens to the pressure line 517 and therefore limits the pressure-side behind-vane pressure pDH. The increase of the pressure-side behind-vane pressure pDH during operation is determined, inter alia, by the hydraulic resistance in the line 531. This hydraulic resistance is selected in such a way that, on the one hand, at low rotational speeds, a pressurization of the pressure-side behind-vane pressure duct 511 from the suction-side behind-vane pressure duct 512 is possible; the suction-side behind-vane pressure duct 512 is supplied from the pressure line 517. On the other hand, due to the hydraulic resistance, a certain lower value of the pressure-side behind-vane pressure pDH that is necessary for a good volumetric efficiency of the vane pump is set.
Alternatively, it would also be possible to connect the pressure-side behind-vane pressure duct via the pressure limiting valve to a suction line of the vane pump, so that the pressure limiting valve opens toward a lower pressure level than is the case with the pressure line, whereby the pressure-side behind-vane pressure can be further reduced.
In principle, the embodiments of the approach according to example aspects of the invention can be utilized for a single-stroke vane pump as well as for a multi-stroke vane pump.
The double-stroke vane pump 601 in the exemplary embodiment shown is symmetrically designed, although it can also be asymmetrically designed. In the upper half of the drawing (above the horizontal dash-dotted line), a first self-sufficient delivery region is represented and, in the lower half, a second self-sufficient delivery region is represented. “Self-sufficient delivery regions” is to be understood to mean that, in principle, two pumps are formed within the double-stroke vane pump. The two delivery regions do not affect each other. With the exception of leakage flows, the oil circuits of the two delivery regions are separated. The pressures generated by the two delivery regions can have different levels. Likewise, the particular flow rates can differ in the case of an asymmetrical design of the double-stroke vane pump. For the sake of clarity, essentially only the upper half of the pressure plate 602 is described here. The direction of rotation of a rotor (not shown) about an axis of rotation D is the clockwise direction in the drawing, as represented by the direction-of-rotation arrow R.
The suction region encompasses the suction port 609 and a suction-side behind-vane pressure duct 612, which is arranged radially between the suction port 609 and the axis of rotation D. The suction pressure pS prevails in the suction port and the suction-side behind-vane pressure pSH prevails in the suction-side behind-vane pressure duct 612.
A pressure-side behind-vane pressure duct 611, in which the pressure-side behind-vane pressure pDH prevails, is formed radially within the pressure port 608 in which a pump pressure pP prevails. Similarly to the vane pump in
The suction-side behind-vane pressure region 612 is hydraulically connected to the pressure port 608, in the example shown, via a pressure line 617, so that the suction-side behind-vane pressure region is supplied with operating medium, which is under pump pressure pP. The suction-side behind-vane pressure region 612 and the pressure-side behind-vane pressure duct 611 are connected by a hydraulic resistance 635, which is formed in a line 632. The hydraulic resistance can be designed as a restrictor or an orifice, as in the case of the vane pump 501 in
In the case of a double- or multi-stroke vane pump, the pressure-side behind-vane pressure ducts could theoretically be hydraulically connected to one another, so that only one pressure limiting valve would be necessary for two or more delivery regions of the vane pump. A hydraulic connection of the suction-side behind-vane pressure ducts would also be possible, which would further simplify the configuration and the manufacture.
Modifications and variations can be made to the embodiments illustrated or described herein without departing from the scope and spirit of the invention as set forth in the appended claims. In the claims, reference characters corresponding to elements recited in the detailed description and the drawings may be recited. Such reference characters are enclosed within parentheses and are provided as an aid for reference to example embodiments described in the detailed description and the drawings. Such reference characters are provided for convenience only and have no effect on the scope of the claims. In particular, such reference characters are not intended to limit the claims to the particular example embodiments described in the detailed description and the drawings.
Number | Date | Country | Kind |
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10 2017 223 530.6 | Dec 2017 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/084456 | 12/12/2018 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2019/121188 | 6/27/2019 | WO | A |
Number | Name | Date | Kind |
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20120275945 | Schulz-Andres et al. | Nov 2012 | A1 |
20140301877 | Bohm | Oct 2014 | A1 |
20150267700 | Fujita et al. | Sep 2015 | A1 |
Number | Date | Country |
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2630736 | Mar 1977 | DE |
19546329 | Jun 1997 | DE |
102013224660 | Jun 2015 | DE |
102014222322 | Feb 2016 | DE |
WO 2008092594 | Aug 2008 | WO |
WO 2011042105 | Apr 2011 | WO |
Entry |
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Borchers, ‘Vane Pump with Improved Starting Behavior’—DE102014222322A_MT.pdf (Machine Translation), (2016). (Year: 2016). |
Ungers, ‘Vane Machine with Defined Pressure in the Hindwing Spaces’—DE102013224660A1MT.pdf-DES.pdf (Machine Translation), (2015). (Year: 2015). |
German Search Report DE 10 2017 223 530.6, dated Mar. 17, 2020, (12 pages). |
International Search Report (English Translation) PCT/EP2018/084456, dated Mar. 7, 2019, (2 pages). |
Number | Date | Country | |
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20200340473 A1 | Oct 2020 | US |