Valveless, mechanical pressure control pump

Abstract

Pump, comprising: a housing; a pump body housed in the housing, the pump body comprising an outer cylindrical part and an inner cylindrical part, the outer cylindrical part comprising one or more inlet openings and the inner cylindrical part comprising one or more outlet openings; a piston disposed between the outer cylindrical portion and the inner cylindrical portion and configured to move axially relative to the one or more inlet ports, the piston and an upper portion of the inner cylindrical portion forming a chamber; a first spring disposed at least partially between the piston and the inner cylindrical part; and a second spring disposed between the housing and a bottom of the pump body, the pump body being configured to move axially relative to the housing and compress the second spring when a pressure in the chamber exceeds a preload of the second spring.

Description

TECHNICAL FIELD

[0001] This description relates generally to systems and methods for a valveless, mechanical pressure control pump for use in transmissions and other mechanical systems. BACKGROUND AND SUMMARY

[0002] Dry sump transmission lubrication focuses on lubricating the transmission components and avoids inefficient oil splashes common with other lubrication methods by utilizing a scavenge pump and a positive displacement pump. The scavenge pump lifts fluid from the sump into a static reservoir, and the positive displacement pump delivers a calibrated amount of oil from the static reservoir to the transmission components. To meet the functional requirements of a dry sump transmission, the scavenge pump must be self-priming, large enough to dry the sump, and capable of transferring a two-phase flow.

[0003] The inventors identified problems with existing slurry pumps for the lubrication of dry-sump transmissions. Electric pumps pose a greater risk of leakage. For example, if an electric pump is located inside a transmission, electrical cables must be routed through a transmission housing to electrically couple the electric pump. Another example: if an electric pump is located outside the transmission, a mechanical and / or hydraulic connection must pass through the housing. Parts passing through the housing can create additional potential weak points in the seal, thus increasing the risk of leakage. Mechanically driven pumps (e.g.,Cam-driven pumps (e.g., with cams) can be completely contained within the casing to prevent leakage due to parts passing through the casing, but in mechanically driven pumps, an excessive pressure chamber can build up unless check valves are installed to prevent the pressure from exceeding a threshold. Valves can increase the complexity of a pump, increasing manufacturing resource requirements and potential points of failure.

[0004] Therefore, embodiments are disclosed herein that solve at least some of the problems described above with a valveless, mechanical pressure control pump. In one embodiment, the pressure control pump may include a housing; a pump body housed within the housing, the pump body comprising an outer cylindrical portion and an inner cylindrical portion, the outer cylindrical portion having one or more inlet ports and the inner cylindrical portion having one or more outlet ports; a piston disposed between the outer cylindrical portion and the inner cylindrical portion and configured to move axially relative to the one or more inlet ports, the piston and an upper portion of the inner cylindrical portion defining a chamber; a first spring disposed at least partially between the piston and the inner cylindrical portion;and a second spring disposed between the housing and a bottom of the pump body, wherein the pump body is configured to move axially relative to the housing and compress the second spring when a pressure in the chamber exceeds a preload of the second spring. When the pressure in the chamber exceeds the preload of the second spring, the pump body can move downward to adjust a vertical position of the inlet ports, thereby reducing the flow rate and ultimately the pressure in the chamber to ensure operation within a pressure range at or below a threshold pressure.

[0005] By eliminating the need for valves to control the pressure of the pressure control pump, the pressure control pump can contain fewer parts, thereby reducing design complexity. For example, the pressure control pump can be mechanically driven by a cam, and the reversibility of the cam rotation can further increase versatility for different configurations in the pressure control pump's applications. This allows the pressure control pump to fit into a wide variety of systems without requiring parts such as electrical cables to run through a system housing. The pressure control pump described here meets several requirements for a slurry pump for dry-sump transmission lubrication, including the requirement that the slurry pump be self-priming, have sufficient displacement, and be capable of two-phase flow, while also solving at least some of the problems with current slurry pumps described above.The pressure control pump can be used in a gearbox, but also in other mechanical systems where the suction of a fluid, such as oil, may be desired.

[0006] It should be understood that the above summary is intended to introduce, in simplified form, a selection of concepts that are further explained in the detailed description. It is not intended to identify the most important or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages noted above or elsewhere in this disclosure. SHORT DESCRIPTION OF THE CHARACTERS Fig. 1A shows a body and a piston of a pressure control pump according to an embodiment of the present disclosure. Fig. Figure 1B shows a cross-sectional view of the housing and piston of Fig. 1A. Fig. 2 shows the pressure control pump in a top dead center (TDC) position. Fig. 3 shows the pressure control pump in a bottom dead center (BDC) position. Fig. Figure 4A shows the pressure control pump during an exhaust stroke, which represents the transition from the Fig. 2 shown TDC position to the one shown in Fig. 3 includes the UT position shown. Fig. Figure 4B shows the pressure control pump during a suction stroke, which represents the transition from the Fig. 3 shown UT position to the one shown in Fig. 2 includes the TDC position shown. Fig. 5 shows the pressure control pump in a pressure control position. Fig. 6A shows a view of an opening, e.g., an outlet opening of the pressure control pump. Fig. Figure 6B shows a diagram of a flow coefficient for an orifice such as the orifice in Fig. 6A. Fig. Figure 7 shows a flowchart of an example method for operating a pressure control pump. Fig. 8A and Fig. 8B show an exemplary timing diagram of the operation of a pressure control pump over a first and a second time period, respectively. DETAILED DESCRIPTION

[0007] The present disclosure relates to systems and methods for a pressure control pump. The pressure control pump may include a body and a piston, wherein the piston can move axially relative to the body to pump fluid through the pressure control pump. An example of the body and piston are shown in the Fig. 1A and Fig. 1B, together with a first spring that guides the movement of the piston. The housing and the piston are in Fig. 2, which also includes a cam that causes the movement of the piston, as well as a housing and a second spring that can provide pressure control during pumping of fluid by the pressure control pump. Fig. 2 shows in particular a TDC position (top dead center) of the pressure control pump, and Fig. 3 shows a BDC position (bottom dead center) of the pressure control pump. Fig. Figure 4A shows the pressure control pump during an exhaust stroke, where during the transition from the TDC position of Fig. 2 to the UT position of Fig. 3 Fluid is forced out of the pump through one or more outlet ports. Conversely, during a suction stroke, the fluid can enter the pressure control pump through one or more inlet ports, as shown in Fig. 4B. The pressure control pump may be arranged in a mechanical system such that the fluid enters the pump from a first part of the mechanical system that is fluidly connected to the inlet ports and exits the pump in a second part of the mechanical system that is fluidly connected to the outlet ports. As a non-limiting example, the mechanical system may be a transmission in which the first part is a sump and the second part is a surge tank. During the exhaust stroke, the pressure in a chamber of the pressure control pump may rise above a desired pressure range, e.g., below a threshold. In particular, a pressure differential across the one or more outlet ports, such as those in Fig. 6A, due to the relationships between fluid properties, flow rate and orifice geometry, as shown in a diagram in Fig. 6B of an outlet coefficient across the opening. Thus, by vertical movement of the pump body and thus the inlet openings, the pressure control pump can maintain a pressure in the pump chamber at or below a threshold pressure, as in a pressure control position as in Fig. 5 in the order shown. A method by which a pressure control pump, such as the pressure control pump of Fig. 2-5, can work, is in Fig. 7, including the execution of an intake stroke, an exhaust stroke and pressure control. Fig. 8A and Fig. 8B show time diagrams of events of interest during the operation of the pressure control pump.

[0008] A pressure control pump may comprise a body which is inserted into the Fig. 1A and Fig. 1B is shown as an example. Fig. 1A shows a first view 102 of a body 100 that may include a first inlet opening 120 positioned on an inlet groove 121 and a second groove 106. Fig. 1A further shows a piston 103, which may be cylindrical and is configured to be at least partially located within the housing 100. Fig. Figure 1B shows a cross-sectional view 104 of the body 100 and the piston 103 along the Fig. 1A shown section A-A', and Fig. 1B additionally shows a piston spring 101. Fig. 1A and Fig. 1B also show reference axes 150, including an x-axis, y-axis, and z-axis. In one example, the z-axis may be parallel to the direction of gravity, so that a negative z-direction may be identical to the direction of gravity. Additionally or alternatively, the z-axis may be a direction of axial movement of the piston 103 relative to the housing 100. The reference axes are shown in the Fig. 1B-5 is shown in more detail.

[0009] The housing 100 may include an outer cylindrical portion 144 having an inlet groove 121 in which a first inlet opening 120 and a second inlet opening 123 are located. The inlet groove 121 may be a portion of the outer cylindrical portion 144 of the housing 100 with a reduced diameter. Consequently, the inlet groove 121 may have a smaller thickness than the remainder of the outer cylindrical portion 144. The first inlet opening 120 and the second inlet opening 123 may be arranged opposite each other (e.g., across a diameter of the outer cylindrical portion 144 parallel to the x-axis) along the inlet groove 121. The first inlet opening 120 and the second inlet opening 123 may each be circular, at least in some embodiments. In addition, the first inlet opening 120 may have a beveled edge 119 defining an opening of the inlet opening 120.For example, the beveled edge 119 may be curved so that the opening is circular. Due to the beveled edge 119, the size of the opening (e.g., diameter) may gradually decrease along the thickness of the inlet groove 121 toward the interior of the body 100 (e.g., in the positive x-direction). The second inlet opening 123 may have a similarly shaped beveled edge (not shown). The curved, beveled edges (e.g., the beveled edge 119) may allow fluid to flow more smoothly into the body 100 through the first inlet opening 120 and the second inlet opening 123 than could be achieved with sharp corners (e.g., 90-degree corner edges). In some examples, the first inlet opening 120 and the second inlet opening 123 may be drilled tangentially with respect to the body 100 such that the first inlet opening 120 and the second inlet opening 123 are elongated in the y-direction compared to the z-direction.In other embodiments, the first inlet port 120 and the second inlet port 123 may have other shapes, sizes, and / or arrangements. For example, in some embodiments, the inlet ports may be elliptical, rectangular, or other shapes depending on the desired fluid flow therethrough. In another example, the housing 100 may include three or more inlet ports radially disposed around the outer cylindrical portion 144 of the housing 100 at the inlet groove 121, or the housing 100 may include only one inlet port. The outer cylindrical portion 144 may further include the second groove 106, which may be configured (e.g., sized, shaped) to receive a sealing ring, such as the one shown in FIGS. Fig. 2-5 shown sealing ring 135.

[0010] The body 100 may further include an inner cylindrical portion 142, the hollow center of which may form the outlet chamber 136. The inner cylindrical portion 142 may be centrally disposed within a hollow center of the outer cylindrical portion 144. For example, the inner cylindrical portion 142 may be housed within the outer cylindrical portion 144. Further, the body 100 may have a cylindrical base 156 from which the inner cylindrical portion 142 and the outer cylindrical portion 144 may extend axially. For example, the inner cylindrical portion 142 and the outer cylindrical portion 144 may be physically connected via the body base 156. The inner cylindrical portion 142 may extend a lesser height 160 from the base than the height 159 that the outer cylindrical portion 144 extends from the body base 156. In addition, the inner cylindrical part 142 may have a smaller thickness 147 than the thickness 145 of the outer cylindrical part.An outer cylindrical surface 151 of the inner cylindrical portion 142 may be spaced from an inner cylindrical surface 149 of the outer cylindrical portion 144 by a distance 158, and a top surface 154 of the inner cylindrical portion 142 (e.g., a top surface of the inner cylindrical portion 142) may be spaced from the piston 103 by a varying distance 112 with a chamber 137 therebetween. A cylindrical cavity 109 may be formed between the inner cylindrical portion 142 and the outer cylindrical portion 144, defined by the inner cylindrical surface 149 of the outer cylindrical portion 144, the outer cylindrical surface 151 of the inner cylindrical portion 142, and a top surface 155 of the base body 156. Thus, the cylindrical cavity 109 may be in fluid communication with the chamber 137.The inner cylindrical portion 142 may include an outlet opening 122 disposed at and extending through the top surface 154 of the inner cylindrical portion 142. The outlet opening 122 may be positioned vertically higher than the first inlet opening 120 and the second inlet opening 123. The outlet opening 122 may be an opening sized to provide the desired fluid flow through the opening, as shown in FIGS. Fig. 6A and Fig. 6B. The chamber 137 and the outlet chamber 136 may be in fluid communication with each other via the outlet opening 122. For example, a fluid, such as oil and / or air, may flow from the chamber 137 through the outlet opening 122 in the negative z-direction into the outlet chamber 136. In other examples, the inner cylindrical portion 142 may include more than one outlet opening, e.g., two or more outlet openings.

[0011] The piston 103 may be a bucket tappet having a cylindrical shape with a circular top portion 105 and a cylindrical wall 146, including a skirt edge 131 on a bottom side of the wall 146. In some embodiments, the diameter of the piston 103 may be between 30 and 33 millimeters, inclusive. A cavity of the piston 103 may form part of the chamber 137, and the cavity may be configured to receive the piston spring 101. The piston spring 101 and the piston 103 may be configured to fit between the outer cylindrical portion 144 and the inner cylindrical portion 142 of the housing 100, such that the outer cylindrical portion 144 may circumferentially surround at least a portion of the piston 103, the piston 103 may circumferentially surround at least a portion of the piston spring 101, and the piston spring 101 may circumferentially surround the inner cylindrical portion 142. In some examples, the piston spring 101 may be in surface contact with the inner cylindrical portion 142.In other examples, the piston spring 101 may be spaced from the inner cylindrical portion 142 to reduce friction due to movement of the piston spring 101. Further, a first end of the piston spring 101 may be connected to the piston 103 at a first connection point (in . Fig. 1B not shown) and a second end of the piston spring 101 may be connected to the body 100 at a second connection point 152. The first connection point is located on a surface on the top surface 105. The second connection point 152 is located on the top surface 155 of the base body 156 between the inner cylindrical part 142 and the outer cylindrical part 144. When the piston spring 101 is attached to the second connection point 152, it may contact the top surface 155 via the second connection point 152.

[0012] In the Fig. 1B, the outer cylindrical portion 144 and the inner cylindrical portion 142 can accommodate the piston 103 as the piston 103 moves (e.g., along the z-axis) during compression and extension of the piston spring 101, and can restrict the movement of the piston 103 along the x-axis and y-axis. In this way, the stem edge 131 of the piston 103 can be lowered and raised to increase and decrease, respectively, the coverage of the first inlet port 120 and the second inlet port 123. For example, the piston spring 101 can be compressed and the piston 103 can be moved downward (e.g., in the negative z-direction) so that the stem edge 131 can be lowered to further cover the first inlet port 120 and the second inlet port 123. Consequently, the volume of the chamber 137 can be reduced.In another example, the piston spring 101 may be extended and the piston 103 may be moved upward so that the stem edge 131 may be raised to reduce the coverage of the first inlet port 120 and the second inlet port 123. Therefore, the volume of the chamber 137 may increase. The movement of the elements of the pressure control pump, including the piston spring 101 and the piston 103, is described further below with reference to FIG. Fig. 2-4B.

[0013] In Fig. 2 shows a pressure control pump 200 which comprises the housing 100, the piston spring 101 and the piston 103 of the Fig. 1A-B. Some in Fig. 1A-B shown labels are in Fig. 2 for clarity. The pressure control pump 200 may also include a cam 162, a housing 130, a spring 132, one or more end stop devices 134, and a sealing ring 135. The housing 130 may have a cylindrical shape and circumferentially surround the body 100 such that the body 100 may be located in a hollow interior of the housing 130. Thus, the housing 100 may be housed in the housing 130. The housing 130 may have a housing bottom 141 on the underside of the housing. The housing bottom 141 may have a cylindrical shape and a hollow interior with an inner diameter that is smaller than the inner diameter of the hollow interior of the rest of the housing 130. In some examples, the inner diameter of the housing bottom 141 (e.g., the inner diameter of the hollow interior of the housing bottom 141) may be substantially the same (e.g.,within 5%) as an inner diameter of the inner cylindrical portion of the body 100. In some examples, the housing 130 may be a casting of a transmission in which the pressure control pump is employed. The housing 130 may be located at a fixed location (e.g., relative to the rotational axis 166) such that the housing 130 does not move due to the movement of other elements of the pressure control pump 200.

[0014] A space formed by the inlet groove 121 of the housing 100 and the housing 130 together forms an intake annulus 133. The intake annulus 133 may be connected to a first part of a mechanical system, e.g., a sump of the transmission (not shown), via one or more holes in the housing 130, e.g., a first hole 153 and a second hole 157. The first hole 153 and the second hole 157 may have any suitable shape, e.g., circular, elliptical, or the like. In some examples, the first hole 153 and the second hole 157 may be drilled tangentially into the housing 130 so that their shapes resemble the first inlet port 120 and the second inlet port 123. In other examples, the first hole 153 and the second hole 157 may be manufactured differently. In some examples, the one or more holes may have a different geometry than the inlet openings.

[0015] The one or more holes may each be aligned with an inlet opening in some examples. For example, the first hole 153 may be aligned with the first inlet opening 120 and the second hole 157 may be aligned with the second inlet opening 123 such that their centers are aligned along a common axis (e.g., parallel to the x-axis). Furthermore, the one or more holes may each have a cross-sectional area perpendicular to the axis (e.g., in a yz-plane) that is greater than or equal to a cross-sectional area perpendicular to the axis of the inlet opening with which the hole is aligned. For example, the first hole 153 may be sized to have a cross-sectional area equal to or greater than the first inlet opening 120, and the second hole 157 may be sized to have a cross-sectional area equal to or greater than the second inlet opening 123.

[0016] In other examples, the one or more holes (e.g., first hole 153 and second hole 157) may not be aligned with the inlet openings (e.g., first inlet opening 120 and second inlet opening 123). For example, housing 130 may have more or fewer holes than inlet openings and / or the holes may be offset from the inlet openings. In such an example, the total cross-sectional area of the holes (e.g., the sum of the cross-sectional areas of the individual holes) may be greater than or equal to the total cross-sectional area of the inlet openings (e.g., the sum of the cross-sectional areas of the individual inlet openings).

[0017] A sealing ring 135 (e.g., an O-ring) may be positioned in the second groove 106 of the housing 100 such that a seal is formed between the housing 130 and the housing 100 at the sealing ring 135. In this way, the fluid in the intake annulus 133 cannot flow between the housing 100 and the housing 130 past the sealing ring 135 (e.g., toward the spring 132 and the outlet chamber 136). In at least some embodiments, the seal formed by the sealing ring 135 may be a hermetic seal. The intake annulus 133 may also be in fluid communication with the chamber 137 via the first inlet port 120 and the second inlet port 123, at least in some positions of the piston 103, including a top dead center (TDC) position 250 of the Fig. 2 pressure control pump 200 shown.

[0018] The spring 132 may be positioned between the housing 100 and the housing bottom 141 of the housing 130 such that the spring 132 may overlie a top surface 170 of the housing bottom 141 of the housing 130 and the housing 100 may overlie a top surface of the spring 132. Furthermore, a first end of the spring 132 may be physically connected to the bottom 108 of the housing 100 and a second end of the spring 132 may be physically connected to the top 170 of the housing bottom 141. The first end of the spring 132 may be in a relatively positive z-direction compared to the second end of the spring 132, and the compression and / or extension of the spring 132 may occur parallel to the z-axis in response to the movement of other elements of the pressure control pump.In at least some embodiments, the body spring 132 may include one or more disc springs in series, each having a plurality of axially aligned discs 139 that form an opening 143 through the center of the body spring 132 as an extension of the outlet chamber 136 formed by the inner cylindrical portion 142 of the body 100. For example, the body spring 132 may include four disc springs having an outer diameter of 40 mm, an inner diameter of 14.3 mm, and a thickness of 1.25 mm. In other examples, other dimensions may be used. In other embodiments, the body spring 132 may be a single spring, such as a compression, helical, or coil spring. Additionally, in some examples, the body spring 132 may be an elastic body that acts as a spring.

[0019] One or more end stop devices 134 may be physically coupled to interior surfaces of the housing 130 such that the vertical movement of the body 100 relative to the housing 130 is limited by the one or more end stop devices 134. For example, the spring 132 may urge the body 100 toward the cam 162 until an upper portion 172 of the body 100 contacts the one or more end stop devices 134 and further upward movement of the body 100 is prevented. In some embodiments, the one or more end stop devices 134 may be a ring (and thus, the one or more end stop devices 134 may comprise a single stop device). In other embodiments, the one or more end stop devices 134 may comprise two or more end stop devices, such as two or more segments (e.g.,elastic pins) arranged radially around and in physical contact with the inner wall of the outer cylindrical part 144.

[0020] The cam 162 may have a cylindrical shape and include an opening 164 defined by a cylindrical inner surface 165 through which a shaft (not shown) may extend along the y-axis. The cam 162 may further include a notch 168 in the opening 164 (e.g., formed by the inner cylindrical surface 165) into which a radially projecting portion of the shaft of complementary geometry may engage the notch 168 such that rotation of the shaft results in substantially (e.g., within 5%) the same angular velocity of the cam 162 about a common rotational axis 166. In some examples, the shaft may be integrally formed with the cam 162. The opening 164 may be circular and offset from a center (e.g., in a cross-section in the xz plane) of the cam 162, and the rotation axis 166 may be fixed at a center of the opening 164.In this manner, the cam 162 can rotate asymmetrically, allowing the cam 162 to extend radially by different distances depending on the angular position of the cam 162. The rotation of the cam 162 can be clockwise or counterclockwise about the rotation axis 166 to operate the pressure control pump 200, thereby allowing the pressure control pump 200 to be used in a variety of system configurations, for example, in a transmission. The rotation of the cam 162 and the shaft can be driven by a suitable rotating source such as a motor, an electric machine, a transmission input shaft, or the like. In other examples, the pressure control pump 200 can include a cam hold-down device and a lever arm.

[0021] The cam 162 may be in direct physical contact with the top surface 105 of the piston 103, and the cam 162 may be eccentric, so that the cam 162 may change a position (e.g., along the z-axis) of the piston 103 relative to the body 100 when the cam 162 is rotated by the shaft. In other words, the piston 103 may be moved axially by the radial movement of the cam 162 due to the rotation of the cam 162. Thus, the energy may be transferred via the cam 162 to the pressure control pump 200. The piston spring 101 may be as in Fig. 1A-B and can press against the piston 103 (e.g., in the positive z-direction), while the cam 162 presses against the piston 103 (e.g., in the negative z-direction). Thus, the piston 103 can be spring-loaded, so that the piston spring 101 can push upward with the spring force against the downward force exerted on the piston 103 by the cam 162. Furthermore, the upward movement of the piston 103 can be achieved by the spring force of the piston spring 101, and the downward movement of the piston by the force of the cam 162. Fig. 2, the pressure control pump 200 is particularly illustrated in a TDC position 250 in which the piston 103 is in an uppermost position (e.g., most positive z-position) because a varying distance 167 between the rotation axis 166 and the top side 105 of the piston 103 (e.g., in the z-direction) is minimized. The skirt edge 131 of the piston 103 may be in the uppermost position such that the first inlet port 120 and the second inlet port 123 are less covered by the wall 146 of the piston 103 than in at least some other positions of the pressure control pump, e.g., in the bottom dead center position (as described in more detail below). The first inlet port 120 and the second inlet port 123 may be at least partially uncovered in the TDC position.In some examples, the piston 103 may not cover the first inlet port 120 and the second inlet port 123 at all in the TDC position because the skirt edge 131 may be located above or on top of the first inlet port 120 and the second inlet port 123. In other examples, the piston 103 may partially cover the first inlet port 120 and the second inlet port 123 in the TDC position. The housing spring 132 may be more extended in the TDC position compared to other positions of the pressure control pump, so that the housing 100 is pushed upward against the one or more end stop devices 134 by the housing spring 132.

[0022] The angular position of the cam 162 with minimum cam lift, as in Fig. 2 and described above, is referred to here as the "reference angular position" and is understood as a 0-degree rotation of the cam. The reference angular position can be used for comparison to other positions described below.

[0023] Fig. 3 shows the pressure control pump 200 of Fig. 2 in a UT position (Bottom Dead Center) 350. Fig. 3 is labeled similarly, and no recurring elements are introduced, but some part numbers from Fig. 2 for reasons of clarity Fig. 3. In the BDC position 350, the cam 162 may be in a position rotated by 180 degrees (e.g., clockwise or counterclockwise around the rotation axis 166) compared to the reference angular position, which results in the varying distance 167 being maximized, the piston spring 101 being compressed, and the piston 103 being in a lowest position (e.g., in the negative z-direction). Thus, the piston 103 may be movable between the TDC position 250 and the BDC position 350. The body 100 may be in the same position as in the TDC position 250 of Fig. 2, with the spring 132 urging the body 100 upward against the one or more end stop devices 134. In some embodiments, the top surface 105 of the piston 103 may be aligned with the top surface 172 of the housing 100 in the BDC position (e.g., in an xy plane). Additionally or alternatively, the piston 103 may remain spaced from the housing 100 in the BDC position 350, but to a lesser extent than in the TDC position 250, as shown in Fig. 2 shown.

[0024] Consequently, the first inlet port 120 and the second inlet port 123 can be closed by the piston 103 because the skirt edge 131 of the piston 103 is located at the bottom or below the first inlet port 120 and the second inlet port 123. In other words, the fluid connection between the intake annulus 133 and the space 137 via the first inlet port 120 and the second inlet port 123 can be blocked by the piston 103 in the BDC position 350 of the pressure control pump 200.

[0025] Fig. 4A and Fig. 4B show an exhaust stroke 400 and an intake stroke 410 of the pressure control pump 200. The exhaust stroke 400 may be a transition from the TDC position 250 of Fig. 2 to UT position 350 of Fig. 3, and conversely, the intake stroke can be a transition from the BDC position 350 of Fig. 3 to TDC position 250 from Fig. 2. During the transition between the TDC and BDC positions, as described above, the piston 103 may move, the piston spring 101 is compressed and / or extended, and other elements remain in the same position. For example, the housing 100 and the housing 130 may not move relative to the rotational axis 166. The movement of the body 100 may occur in response to a pressure that exceeds a threshold pressure, as described below with reference to Fig. 5. The pressure control pump 200 may further oscillate between the TDC and BDC positions in accordance with the rotation of the cam 162, wherein the speed at which the piston 103 moves is related to the angular velocity of rotation of the cam 162.

[0026] Beginning with the exhaust stroke 400, the cam 162 may rotate, for example, clockwise, as shown by arrow 408, between the reference angular position and 180 degrees therefrom, thereby exerting a force on the piston 103 in a downward direction indicated by arrow 402. Consequently, the piston may be moved downward (e.g., in the negative z-direction) such that the skirt edge 131 of the piston 103 may move downward (see arrow 404), thereby increasing the coverage of the first intake port 120 and the second intake port 123. When the skirt edge 131 reaches the bottom of the first inlet port 120 and the second inlet port 123, the first inlet port 120 and the second inlet port 123 fluidly separate the intake annulus 133 from the chamber 137, thereby increasing the pressure in the chamber 137.An increase in pressure in chamber 137 may cause fluid to flow from chamber 137 through outlet port 122 into outlet chamber 136. Thus, a first portion of the outlet stroke, in which first inlet port 120 and / or second inlet port 123 are not fully closed by piston 103, may not contribute to fluid flow to outlet chamber 136. In contrast, a second portion of the outlet stroke, in which first inlet port 120 and second inlet port 123 are fully closed, may contribute to pressure control pump 200 delivering flow, for example, to a storage tank or a quiescent reservoir. The first portion is hereby referred to as the inactive portion and the second portion as the active portion.

[0027] During the intake stroke 410, the piston spring 101 may urge the piston 103 away from the body 100 in a direction indicated by arrow 412, which may create suction to draw fluid (e.g., lubricant, oil, air) through the intake annulus 133 and into the chamber 137 as the volume of the chamber 137 expands. The stiffness of the piston spring 101 may be selected based on the mass of the piston 103, the force exerted on the piston due to the suction effect, and / or a desired acceleration of the piston 103, which depends on the camshaft speed and camshaft profile. When the piston 103 is raised, the first inlet port 120 and the second inlet port 123 are opened to connect the intake annulus to the chamber 137 so that fluid from the intake annulus 133 can enter the chamber 137, as indicated by the arrows 414.The first inlet port 120 and the second inlet port 123 may, as described above, be shaped with a greater width (e.g., dimension parallel to the y-axis) than height (e.g., dimension parallel to the z-axis) so that an amount of fluid entering the pressure control pump 200 during the intake stroke is maximized without increasing the portion of the intake stroke in which the first inlet port and the second inlet port are not closed by the piston 103.

[0028] Fig. 4B further includes a first portion 418 and a second portion 420 of a mechanical system in which the pressure control pump 200 may be housed. The first portion 418 may be a first fluid reservoir and the second portion 420 may be a second fluid reservoir, wherein it is desired that fluid be drawn from the first fluid reservoir and supplied to the second fluid reservoir. For examples where the mechanical system is a transmission, the first portion 418 may be a sump of the transmission, the second portion 420 may be a quiescent reservoir, and the fluid may be oil. The first portion 418 may be in fluid communication with the chamber 137 via the first inlet port 120, the second inlet port 123, the first bore 153, and the second bore 157 when the first inlet port 120 and the second inlet port 123 are not covered by the piston 103. The second part 420 may communicate with the outlet chamber 136.In this way, the pressure control pump 200 can pump fluid from the first part 418 to the second part 420.

[0029] As the cam 162 rotates, the pressure control pump 200 can continue to oscillate between positions corresponding to the rotation of the cam 162. The speed at which the piston 103 moves is related to the angular velocity of rotation of the cam 162, which can be driven by a motor, an electric machine, an input shaft of a transmission, or the like. The pressure control pump 200 (and in particular the piston 103) can move back and forth between a TDC position and a BDC position. However, there are factors that can cause the pressure in the chamber 137 to rise above a threshold pressure when the first inlet port 120 and the second inlet port 123 are closed, such as the flow rate and the temperature of the fluid. The factors that can increase the pressure in the chamber 137 will be discussed following a brief description of the fluid through an opening in the Fig. 6A-6B and in equation (1) and equation (2) below. Q=CdπDo242(p1−p2)ρ Re=ρvDμ

[0030] Equation (1) shows the relationships between a pressure difference (p2-p1) across an orifice, a volume flow rate of a fluid (Q) flowing through the orifice, a density of the fluid (p), and an outlet coefficient (C d ) across the opening. The pressure difference (p2-p1), for example, is directly related to the volume flow rate (Q) and the density of the fluid (p) and inversely to the outlet coefficient (C d ). Fig. 6A shows a cross-sectional view 600 of an exemplary opening 608 having a length 602 (L o ) and a diameter of 607 (D o), through which a fluid can flow from a first side 604 to a second side 606 in a direction indicated by the arrow 609. Thus, a first pressure (p1) on the first side 604 can be greater than a second pressure (p2) on the second side 606. For example, the opening 608 can be the outlet opening 122 of the Fig. 1A-5, so that the first side 604 may be the chamber 137 and the second side may be the outlet chamber 136. Fig. Figure 6B shows a diagram 610 in which the outlet coefficient (C d ) (shown on the y-axis) as a function of the ratio between the opening diameter (D o ) and the opening length (L o ) times the Reynolds number (R e ) of the fluid (shown on the x-axis). A curve 616 shows the outlet coefficient (C d ) for a fluid flowing through an opening such as the one shown in Fig. 6A or the opening 608 shown in Fig. 1A-5 shown outlet opening 122. The outlet coefficient (C d ) increases along the y-axis of the diagram 610 in the direction 612, and the ratio between the opening diameter (D o ) and the opening length (L o ) times the Reynolds number (R e ) of the fluid increases along the x-axis of diagram 610 towards 614. The Reynolds number (R e ) depends on the velocity, viscosity, and density of the fluid, as shown in equation (2), as well as on the geometry of the system in which the fluid flows. The outlet coefficient (C d ) depends on the fluid properties (e.g. viscosity and density), the flow rate (e.g. volume flow), and the geometry of the orifice (e.g. orifice diameter and orifice length). The outlet coefficient, for example, is directly related to the diameter of the orifice (D o ) and the Reynolds number (R e ) and indirectly with the length of the opening (Lo ), as curve 616 shows.

[0031] To access the Fig. 4A-4B, for example, a cam 162 rotating at high speed may result in a high volume flow of fluid through the opening of the exhaust port 122, thereby increasing the pressure differential between the pressure in the chamber 137 and the pressure in the exhaust chamber 136. Thus, during the portion of the exhaust stroke in which the first inlet port 120 and the second inlet port 123 are closed, the pressure in the chamber 137 may exceed a desired pressure range, for example, when the speed of the cam 162 is relatively high. Additionally or alternatively, a change in the temperature of the fluid flowing through the pressure regulating pump 200 may affect the pressure buildup in the chamber 137. For example, a lower temperature of the fluid flowing through the pressure regulating pump 200 may decrease the viscosity of the fluid and / or increase the density of the fluid.Since the pressure difference is inversely proportional to the Reynolds number, the pressure difference is directly related to the viscosity of the fluid and indirectly to the density of the fluid; therefore, the pressure in chamber 137 may increase due to the lower temperature of the fluid.

[0032] Therefore, the pressure control pump 200 may include a pressure relief mechanism that includes compression of the body's spring 132 and downward movement of the body 100 in response to the pressure in the chamber 137 reaching or exceeding a threshold to prevent the pressure from exceeding the threshold. Specifically, the pressure control pump 200 may move to a pressure control position such that the first inlet port 120 and the second inlet port 123 open when the pressure in the chamber 137 is at least equal to the threshold pressure.

[0033] Fig. Figure 5 shows the pressure control pump 200 in a pressure control position 500, in which the pressure in the chamber 137 has exceeded the threshold pressure in the discharge stroke, so that the spring 132 of the housing is compressed and the housing 100 is compressed compared to the positions in the Fig. 2-4B can be moved downward. In this way, the pressure in the chamber 137 that exceeds the threshold pressure can overcome a spring load on the body spring 132, partially compressing the body spring 132 and forcing the body 100 downward. The movement of the body 100 can occur relative to the housing 130 and the rotation axis 166, both of which can remain in the same position. The sealing ring 135 can slide with the second groove 106 as the housing 100 moves relative to the housing 130. To allow relative movement of the body 100 downward within the housing 130, the distance C between an outer peripheral surface 502 of the body 100 and an inner peripheral surface 504 of the housing 130 can be between 0.1 mm and 0.3 mm.In some examples, clearance C may be substantially equal to (e.g., within 5%) a clearance D between an outer surface of the wall 146 of the piston 103 and an inner cylindrical surface 149 of the outer cylindrical portion 144 of the body 100. The piston 103 may be in the same position as the BDC position 350 of FIG. Fig. 3, since the cam 162 has the same angular position of approximately 180 degrees relative to the reference angular position. For example, the top surface 172 of the housing 100 may be below the top surface 105 of the piston 103. Furthermore, the top surface 172 of the body 100 may be spaced or offset from the one or more end stop devices 134 in the pressure control position. Thus, the downward movement of the housing 100 relative to the piston 103 may cause the first inlet port 120 and the second inlet port 123 to be at least partially lowered below the skirt edge 131 of the piston, thereby fluidly connecting the intake annulus 133 to the chamber 137 and reducing the pressure in the chamber 137 below the threshold pressure. Thus, the downward movement of the body 100 can increase the length of the inactive part of the exhaust stroke and decrease the length of the active part of the exhaust stroke.As a result, the volumetric efficiency of the pressure control pump 200 can be reduced, and thus the volumetric flow rate of fluid through the outlet port 122, thereby reducing the pressure in the chamber 137 below the threshold pressure. Furthermore, in the pressure control position, the top of the inner cylindrical portion 142 can be lowered, thereby increasing the volume of the chamber 137, which contributes to a further pressure reduction in the chamber 137. Thus, the pressure control pump 200 can self-regulate the displacement of the pressure control pump 200 to operate within the desired pressure range.

[0034] Therefore, the pressure control pump 200 may be capable of regulating the pressure in the chamber 137 such that the pressure in the chamber 137 is prevented from exceeding the threshold pressure without the use of valves. More specifically, the ability of the pump 100 to move in response to the pressure in the chamber 137 may allow the pressure control pump 200, which does not include valves, to regulate the pressure in the chamber 137 (e.g., to maintain the pressure in the chamber 137 at or below the threshold pressure). Therefore, the pressure control pump 200 may also be referred to as a valveless pressure control pump.

[0035] In Fig. 7 shows a flowchart illustrating a method for operating a pressure control pump, such as pressure control pump 200. Method 700 may be used, for example, to pump fluid through a pressure control pump. More specifically, method 700 may be used to pump oil from the transmission sump via pressure control pump 200 into a reservoir.

[0036] At 702, a cam is rotated to adjust the position of a piston of the pressure control pump. For example, the cam 162 of the Fig. 2-5, the pressure control pump 200 can be rotated about the rotational axis 166 by a camshaft, which can be rotationally coupled to parts of the transmission. The cam can rotate at a constant rotational speed. Additionally or alternatively, the cam can rotate at different rotational speeds. For example, the cam can rotate at a first angular velocity for a first period of time, and in response to a change in transmission operation (e.g., a gear change), the cam can rotate at a second rotational speed for a second period of time. The rotation of the cam can result in fluid being pumped through the pressure control pump in subsequent steps.

[0037] At 703, the fluid is pumped through the pressure control pump while the cam rotates. Pumping fluid through the pressure control pump may initiate a suction stroke (e.g., suction stroke 410 in Fig. 4B) to draw fluid through inlet ports of the pump, as indicated at 704. For example, fluid (e.g., oil and / or air) from a sump of the transmission may enter the pressure control pump 200 through the first inlet port 120 and the second inlet port 123. The cam may be rotated during the intake stroke so that the cam lift is reduced, the piston is moved toward the cam rotation axis, and the piston spring is extended. Consequently, the inlet ports may be opened, allowing fluid to flow through them into the pressure control pump.

[0038] Pumping fluid through the pressure control pump may also require the performance of a discharge stroke (e.g. discharge stroke 400 in Fig. 4A) to discharge the fluid through an outlet port of the pump, as indicated at 706. For example, the fluid from the pressure control pump 200 may be directed through the outlet port 122 into the outlet chamber and then into a quiescent reservoir. The cam may be rotated during the exhaust stroke to increase the cam lift, compress the piston spring, and move the piston away from the cam's rotational axis. As a result, the inlet ports may be closed during the active portion of the exhaust stroke, and the fluid may be forced out of the pressure control pump by a pressure differential at the outlet port.

[0039] At 708, the pressure in the pump chamber is translated into axial movement of the pump body when the pressure in the chamber exceeds a threshold. For example, the body 100 of the pressure-regulating pump 200 may move away from the cam 162 due to the compression of the body spring 132 when the pressure in the chamber 137 reaches or exceeds the threshold. As a result, the length of the inactive portion of the discharge stroke may be extended, reducing the pressure back below the threshold pressure. Once the pressure in the chamber has dropped to or below the threshold pressure, the housing spring may push (e.g., move) the housing upward toward the cam.

[0040] In Fig. 8A is a timing diagram 800 for the operation of a pressure control pump such as that shown in Fig. 1A-5, over a first time period between t0 and t12. The timing diagram 800 includes three example rotation cycles of a cam, such as cam 162, rotating about the rotation axis 166 during the first time period, as shown in the Fig. 2-5. One rotation cycle of the cam comprises one complete rotation from the reference angular position defined above, or a rotation from 0 degrees to 360 degrees. The time diagram 800 shows a first diagram 802 with a first curve 810 for the pressure of a chamber over time, a second diagram 804 with a second curve 812 for an angular position of the eccentric, a third diagram 806 with a third curve 814 for a vertical displacement of a piston, and a fourth diagram 808 with a fourth curve 816 for a vertical displacement of a body. The first diagram 802 includes a threshold pressure 811. The second diagram 804 also includes a 0-degree reference line 826, a 180-degree reference line 824, and a 360-degree reference line 822. The third diagram 806 also includes a TDC reference line 828 and a BDC reference line 830. The fourth diagram 808 also includes a normal reference line 832 and a depressed reference line 834.

[0041] The axes of each diagram (e.g., the first diagram 802, the second diagram 804, the third diagram 806, and the fourth diagram 808) can increase in the directions indicated by the axes arrows. For example, in all four diagrams, time can increase horizontally from t0 to t12, with the intervals between the times marked. It should be understood that time represents relative time, such that t1 is some time after t0, t2 some time after t1, and so on, but does not indicate specific or proportional amounts of time unless noted in the description below. Furthermore, the timing diagram 800 shows an example of various measurements during the operation of a pressure control pump, but does not limit the operation of pressure control pumps. For example, the third curve 814, which shows the vertical position of the piston, is curved similar to a sine wave between t0 and t4.However, with different cam shapes in different embodiments, this curve may appear different. Similarly, the pressure in the chamber represented by the first curve 810 may behave differently (e.g., faster or slower, more or less) than in the example illustrated in the timeline diagram 800, depending on a variety of factors, including the shape of the cam and the rotational speed, the fluid properties and flow rate, and the relative proportions of the pressure control pump components. Thus, the first curve 810 does not constrain the pressure dynamics in a pressure control pump unless specifically referred to in the following description as increasing or decreasing a specific amount or a specific pressure, such as the threshold pressure 811.

[0042] If the pressure control pump operated in the timing diagram 800 is the pressure control pump 200, in an example with brief reference to the Fig. 1-5 in addition to Fig. 8A, the pressure of the chamber shown in the first diagram 802 may correspond to the pressure of the chamber 137, the eccentric may be the cam 162, the piston may be the piston 103, and the body may be the body 100. In the same example, the third curve 814 for the vertical arrangement of the piston may correspond to the position of the piston 103 along the z-axis, as indicated by the reference axes 150; likewise, the fourth curve 816 for the vertical arrangement of the body may correspond to the position of the body 100 along the z-axis. Thus, the TDC position may be the TDC position 250 of Fig. 2 and the UT position is the UT position 350 in Fig. 3. Furthermore, the normal vertical position of the fourth diagram 808 may be the position of the body 100 when it is in contact with the end stop devices 134, while the lowered position may be the position of the body 100 at maximum compression of the body spring 132. The threshold pressure 811 may be the pressure at which the spring load of the body spring 132 is overcome.

[0043] Back to Fig. 8A and beginning with a first cycle that takes place between t0 and t4, the eccentric starts at t0 in a 0-degree angular position (e.g., the reference angular position), which corresponds to a TDC position of the piston and a relatively low pressure. Between t0 and t1, the pressure control pump is in the inactive part of a first exhaust stroke, as shown in Fig. 4A. At t1, the piston is lowered far enough to cover the inlet ports of the pressure control pump, so that the pressure in the chamber begins to build up during the active part of the exhaust stroke between t1 and t2.

[0044] Between t1 and t2, the pressure control pump is in the active part of the first exhaust stroke, so that the chamber is sealed against incoming fluid through the inlet ports covered by the piston. The pressure increase (e.g., due to a reduction in the chamber volume), which is reflected in the rise of the first curve 810, can drive fluid from the chamber into the exhaust chamber, thus pushing the fluid out of the pump through the exhaust port. For example, the oil can flow from the chamber into the exhaust chamber and then into a static reservoir.

[0045] Between t2 and t4, the pressure control pump is in a first suction stroke. At t3, the inlet ports are opened, allowing fluid communication between the chamber and the outside of the pump via one or more holes in the housing (e.g., the first hole 153 and the second hole 157 in the Fig. 2 to 5) and the intake ports are restored. This causes the piston to move upwards back toward the TDC marked by the TDC reference line 828, and the pressure in the chamber is reduced as suction builds up. During the intake stroke, the pressure reduction directs a fluid flow from outside the pressure control pump via the inlet ports and bores into the interior of the pressure control pump, more precisely into the pressure control pump chamber. For example, oil from the sump of a transmission can flow into the pressure control pump chamber via one or more inlet ports and one or more bores.

[0046] The pressure never reaches the threshold pressure 811 at any time between t0 and t4, as shown by the first curve 810. Therefore, during the first cycle, the housing remains in the normal vertical position marked by the normal reference line 832, while the piston moves vertically according to the rotation of the cam, resulting in pressure fluctuations represented by the first curve 810 between t4 and t5. For example, the piston is in the TDC position when the angular position is 0 degrees, or when the second curve 812 is connected to the reference line 826 or the reference line 822, and the piston is in the BDC position when the angular position is 180 degrees, or when the second curve 812 intersects the reference line 824. In addition, the pressure in the chamber decreases between t0 and t4 during the corresponding intake stroke (e.g. during the transition from BDC to TDC) and decreases during the active part of the intake stroke (e.g.part of the transition from TDC to TDC). At t4, the first cycle ends with the return of the piston to the TDC position and with the return of the cam angular position to the reference angular position, as shown in the third diagram 806 and the second diagram 804, respectively.

[0047] A second cycle occurs between t4 and t8, with a second exhaust stroke between t4 and t6 and a second intake stroke between t6 and t8. The second cycle may extend over a shorter period of time than the first cycle. That is, the time between t4 and t8 may be shorter than the time between t0 and t4. At t5, the intake ports are closed, resulting in a pressure increase during the active part of the second exhaust stroke between t5 and t6, as shown by the first curve 810. In addition, the pressure in the chamber reaches the threshold pressure 811 between t5 and t6. For example, during the second cycle, the cam speed may be higher and / or the fluid temperature may be lower than during the first cycle, in which the threshold pressure was not reached, resulting in a higher pressure in the chamber that reaches the threshold pressure.Thus, the housing is moved downward to the lowered position marked by the lowered reference line 834 between t5 and t6 to prolong the active part of the second exhaust stroke and thereby reduce the pressure in the chamber below the threshold pressure 811. As shown in . Fig. 5, the movement of the body can be triggered by compression of the spring when the pressure indicated by the first curve 810 exceeds the threshold pressure 811. Between t5 and t6, the body is also raised back to the normal position indicated by the normal reference line 832, because the pressure in the chamber represented by the first curve 810 drops below the threshold pressure 811. When the angular position of the cam represented by the second curve 812 exceeds 180 degrees or crosses the 180-degree reference line 824 at t6, the pressure control pump transitions from the second exhaust stroke to the second intake stroke, so that the pressure of the chamber represented by the first curve 810 continues to decrease thereafter.

[0048] A third cycle occurs between t8 and t12, including a third exhaust stroke between t8 and t10 and a third intake stroke between t10 and t12. The third cycle may be shorter than the second cycle. For example, the time between t8 and t12 may be shorter than the time between t4 and t8. The angular position of the cam and the vertical position of the piston follow similar trajectories to those of the second cycle between t4 and t8, albeit over a relatively shorter period of time, while the pressure and vertical displacement of the body change differently. Thus, it can be seen that the pressure may not follow the same pattern between cycles in which the pressure reaches the threshold due to factors affecting the chamber pressure. For example, the cam lobe may rotate at a higher speed between t8 and t12 than between t4 and t8.Additionally or alternatively, the temperature of the fluid pumped by the pressure control pump may be lower between t8 and t12 than between t4 and t8.

[0049] The operating conditions that affect the pressure buildup in the chamber (e.g., the speed of the cam and the temperature of the pumped fluid) can vary from cycle to cycle. Consequently, in at least some examples, whether the pressure control pump moves to the pressure-regulating position to prevent the threshold pressure from being exceeded can depend on the operating conditions. For example, the speeds of the cams during the second and third cycles can be higher than the speeds of the cams during the first cycle. Additionally or alternatively, the temperature of the pumped fluid can be lower during the second and third cycles than during the first cycle. As a result, the threshold pressure was reached in the second and third cycles, but not in the first cycle. Thus, the pressure in the chamber can reach the threshold pressure during some cycles, and the pressure control pump can then move to the pressure-regulating position.

[0050] In Fig. 8B, the timing diagram 800 is shown over a second period from t20 to t27, which may be before or after t0 to t12, as in Fig. 8A. In addition, there may be time intervals between the Fig. 8A (e.g. the first period from t0 to t12) and Fig. 8B (e.g., the second time period between t20 and t27). The time diagram 800 includes diagrams, curves, and lines as shown in Fig. 8A, which are labeled accordingly. The timing diagram 800 also shows an O / C reference line 829 on the third diagram 806 in Fig. 8B, which shows the vertical placement of the piston where the intake ports are open or closed.

[0051] A fourth cycle occurs between t20 and t27, with a fourth exhaust stroke between t20 and t24 and a fourth intake stroke between t25 and t27. The fourth cycle begins at t20, with the piston in the TDC position, the housing in its normal vertical position, and the cam in the reference angular position. Between t20 and t21, the pressure control pump is in an inactive part of the fourth exhaust stroke. At t21, the intake ports are closed, as shown by the third curve 814, which intersects the O / C reference line 829 and moves to the BDC reference line 830. The pressure therefore begins to rise at t21 and reaches the threshold pressure 811 at t22. Subsequently, at t22, the body begins to move downward to increase the volume in the chamber and thus prevent a further increase in pressure in the chamber. At t23, the body returns to the normal vertical position and the pressure begins to decrease.At t24, the piston then reaches the BDC position when the cam reaches an angular position of 180 degrees. In other examples where the threshold pressure is reached, the piston's BDC position may be reached before the body returns to its normal position and the pressure is reduced.

[0052] Timing diagram 800 shows a greater gap between t24 and t25 than may be the case with other time intervals to more clearly illustrate the timing and cause of the pressure drop. The pressure in the chamber may continue to drop even after the housing returns to its normal vertical position at BDC as fluid flows out of the chamber through one or more exhaust ports. At t25, the fourth intake stroke begins, resulting in a further pressure drop as the chamber volume is increased, followed by a pressure increase after t26 as fluid flows into the chamber due to the inlet ports opened at t26.

[0053] As shown in the time diagram 800 in the Fig. 8A and Fig. As shown in Figure 8B, the pressure control pump maintains the pressure in the chamber at or below the threshold pressure 811. In this way, the pressure control pump can self-regulate the pressure in the chamber by adjusting the displacement of the pressure control pump without the use of valves (e.g., pressure regulating valves, pressure relief valves, balancing valves, etc.). In other words, the pressure in the chamber can be translated into axial movement of the body to maintain the pressure at or below the threshold pressure (e.g., threshold pressure 811).

[0054] The technical effect of the pressure control pump disclosed here is to pump fluid through the pressure control pump and maintain a pressure in a chamber within the pressure control pump at or below a threshold pressure without the use of valves. Thus, the pressure control pump can reduce complexity compared to a pump used in combination with valves for pressure control. Furthermore, the pressure control pump can be mechanically actuated, so that the pressure control pump can be housed in a gearbox housing. Furthermore, due to the sufficient displacement volume and the ability to accommodate two-phase flow, the pressure control pump can be suitable for pumping oil from a gearbox sump into a static container. Thus, the pressure control pump can reduce the complexity of the system in which the pressure control pump is installed, e.g.a gearbox, and reduce resource requirements compared to other pumps because the use of valves is eliminated.

[0055] The disclosure also provides a holder for a pump, comprising: a housing, a pump body housed in the housing, the pump body comprising an outer cylindrical part and an inner cylindrical part, the outer cylindrical part comprising one or more inlet openings and the inner cylindrical part comprising one or more outlet openings, a piston arranged between the outer cylindrical part and the inner cylindrical part and configured to move axially relative to the one or more inlet openings, the piston and an upper part of the inner cylindrical part defining a chamber, a first spring arranged at least partially between the piston and the inner cylindrical part, and a second spring arranged between the housing and a bottom of the pump body, the pump body being configured,to move axially relative to the housing and compress the second spring when a pressure in the chamber exceeds a preload of the second spring. In a first example of the system, the inner cylindrical part is housed in the outer cylindrical part and spaced from the outer cylindrical part by a cylindrical cavity, and wherein the cylindrical cavity is in fluid communication with the chamber. In a second example of the system, optionally including the first example, the inner cylindrical part has a hollow interior defining an outlet chamber, and wherein the outlet chamber is in fluid communication with the chamber via the outlet opening. In a third example of the system, optionally comprising one or both of the first and second examples, the one or more inlet openings are configured to be in fluid communication with the cylindrical cavity. In a fourth example of the system,optionally comprising one or more or each of the first to third examples, the piston is movable between a top dead center (TDC) position and a bottom dead center (BDC) position, wherein in the TDC position, the one or more inlet ports are at least partially uncovered to establish fluid communication between the one or more inlet ports and the cylindrical cavity, and wherein in the BDC position, the one or more inlet ports are covered by the piston and the fluid communication between the one or more inlet ports and the cylindrical cavity is blocked. In a fifth example of the system, optionally comprising one or more or each of the first to fourth examples, the second spring comprises one or more disc springs arranged in series. In a sixth example of the system, optionally comprising one or more or each of the first to fifth examples,The system further comprises: one or more end stop devices coupled to the housing and configured to stop the upward movement of the pump body. In a seventh example of the system, optionally comprising one or more or each of the first to sixth examples, the pump is housed in a transmission, wherein the one or more inlet ports are fluidly connected to a sump of the transmission, and wherein the outlet port is fluidly connected to a surge tank of the transmission. In an eighth example of the system, optionally comprising one or more or each of the first to seventh examples, the pump is configured to move axially through the rotation of a cam connected to a shaft. In a ninth example of the system, optionally comprising one or more or each of the first to eighth examples, the pump does not include valves.

[0056] The disclosure also provides support for a method for a pressure control pump, comprising: maintaining a pressure of a pump chamber of the pressure control pump at or below a threshold pressure by translating the pressure of the pump chamber into axial movement of a pump body of the pressure control pump, wherein the pump body comprises a cylindrical cavity receiving a spring-loaded piston and configured to fluidly couple one or more inlet ports of the pump body to an outlet port. In a first example of the method, the method further comprises: pumping a fluid with the pressure control pump, wherein the pumping comprises drawing the fluid into the pump chamber via the one or more inlet ports during a drawing stroke of the piston and discharging the fluid from the pump chamber via the outlet port during a discharging stroke of the piston.In a second example of the method, optionally including the first example, the pump body is housed in a housing, wherein a body spring is coupled between the pump body and the housing, and wherein maintaining the pressure of the pump chamber at or below the threshold pressure by translating the pressure of the pump chamber into axial movement of the pump body when the pressure of the pump chamber exceeds a preload of the body spring comprises axial movement of the pump body above the pressure in the pump chamber. In a third example of the method, optionally including one or both of the first and second examples, movement of the pump body moves the one or more inlet ports relative to the piston.In a fourth example of the method, optionally comprising one or more or each of the first to third examples, the method further comprises: moving the piston during the exhaust stroke by rotating a cam on a camshaft.

[0057] The disclosure also provides support for a valveless pressure control pump comprising: a pump body having one or more inlet ports and an outlet port; a spring-loaded piston at least partially housed within the pump body and configured to pump fluid into and out of a pumping chamber formed between the piston and the pump body; and a housing housing the piston and the pump body, the pump body configured to move axially relative to the housing. In a first example of the system, the pump body is configured to move vertically downward when the pressure in the pumping chamber exceeds a preload of a spring coupled between the pump body and the housing.In a second example of the system, optionally including the first example, the pump chamber is connected to an outlet chamber via the outlet opening and to a fluid supply via the one or more inlet openings. In a third example of the system, optionally comprising one or both of the first and second examples, the piston is movable between a top dead center (TDC) position and a bottom dead center (BDC) position, wherein in the BDC position the one or more inlet openings are covered by the piston and the fluid supply to the pump chamber is blocked, and wherein in the TDC position the one or more inlet openings are at least partially uncovered to establish fluid communication between the fluid supply and the pump chamber.In a fourth example of the system, optionally comprising one or more or each of the first to third examples, the pump body is cylindrical and the housing is cylindrical, and wherein the one or more inlet openings are arranged in an annular recess of the pump body, the annular recess and the housing together defining a suction annulus.

[0058] The Fig. 1A-5 show example configurations with relative positioning of the various components. Fig.1A-3 and 5 are shown approximately to scale; however, other relative dimensions may be used. When these elements are in direct contact with each other or are directly coupled, they may be referred to as being in direct contact or directly coupled, respectively, at least in one example. Similarly, elements shown side by side or adjacent to each other may be adjacent to each other or adjacent to each other, at least in one example. For example, components that are in surface-to-surface contact with each other may be referred to as being in surface-to-surface contact. As another example, in at least one instance, elements that are separated from each other with only a space between them and that do not have any other components may be referred to as such.In yet another example, elements shown above / below, on opposite sides, or to the left / right of each other may be referred to as such, relative to each other. Further, in at least one example, as shown in the figures, a topmost element or top point of an element may be referred to as a "top" of the component, and a bottommost element or bottom point of the element may be referred to as a "bottom" of the components. As used herein, the terms top / bottom, upper / lower, above / below may refer to a vertical axis of the figures and may be used to describe the positioning of elements of the figures relative to each other. For example, in one example, elements shown above other elements are arranged vertically above the other elements. As another example, the shapes of the elements shown in the figures may be referred to as such (e.g.,B. circular, straight, flat, curved, rounded, beveled, angled, and the like). Furthermore, in one example, elements that are coaxial with each other may be referred to as such. Further, in at least one example, the illustrated elements that intersect each other may be referred to as intersecting elements or as intersecting elements. Furthermore, an element that is illustrated inside another element or outside another element may be referred to as such. In other examples, elements that are offset from each other may also be referred to as such.

[0059] Features described as axial may be approximately parallel to a datum axis unless otherwise noted. The term "approximately" means plus or minus five percent of the range unless otherwise noted. Features described as reverse may be approximately perpendicular to the datum axis unless otherwise noted. Features described as radial may circumferentially surround or extend outwardly from an axis, such as the datum axis, or a component or feature previously described as radial to a datum axis, unless otherwise noted.

[0060] Features described as longitudinal can be approximately parallel to a long axis. A transverse axis can be perpendicular to a long axis. Features described as lateral can be approximately parallel to the lateral axis. A vertical axis can be perpendicular to both a transverse axis and a long axis. Features described as vertical can be approximately parallel to a vertical axis.

[0061] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope than the original claims, are also to be considered included within the subject matter of the present disclosure.

Claims

[1] Pump comprising: a housing; a pump body housed in the housing, the pump body comprising an outer cylindrical part and an inner cylindrical part, the outer cylindrical part comprising one or more inlet openings and the inner cylindrical part comprising one or more outlet openings; a piston disposed between the outer cylindrical portion and the inner cylindrical portion and configured to move axially relative to the one or more inlet ports, the piston and an upper portion of the inner cylindrical portion forming a chamber; a first spring disposed at least partially between the piston and the inner cylindrical part; and a second spring disposed between the housing and a bottom of the pump body, the pump body being configured to move axially relative to the housing and compress the second spring when a pressure in the chamber exceeds a preload of the second spring. [2] A pump according to any one of claims 1, wherein the inner cylindrical part is housed within the outer cylindrical part and is spaced from the outer cylindrical part by a cylindrical cavity, and wherein the cylindrical cavity is in fluid communication with the chamber. [3] The pump of claim 2, wherein the inner cylindrical portion has a hollow interior defining an outlet chamber, and wherein the outlet chamber is fluidly connected to the chamber via the one or more outlet ports. [4] A pump according to claim 2 or 3, wherein the one or more inlet ports are arranged to be in fluid communication with the cylindrical cavity. [5] A pump according to claim 4, wherein the piston is movable between a top dead center (TDC) position and a bottom dead center (BDC) position, wherein in the TDC position the one or more inlet openings are at least partially uncovered to establish fluid communication between the one or more inlet openings and the cylindrical cavity, and wherein in the BDC position the one or more inlet openings are covered by the piston and the fluid communication between the one or more inlet openings and the cylindrical cavity is blocked. [6] A pump according to any one of the preceding claims, wherein the second spring comprises one or more disc springs arranged in series. [7] A pump according to any one of the preceding claims, further comprising one or more end stop devices coupled to the housing and arranged to stop an upward movement of the pump body. [8] A pump according to any one of the preceding claims, wherein the pump is housed in a transmission, wherein the one or more inlet ports are fluidly connected to a sump of the transmission and wherein the one or more outlet ports are fluidly connected to a quiescent reservoir of the transmission. [9] A pump according to any one of the preceding claims, wherein the pump is arranged to move axially by rotation of a cam coupled to a shaft. [10] A pump according to any one of the preceding claims, wherein the pump does not contain any valves. [11] Valveless pressure control pump, comprising: a pump body with one or more inlet openings and one outlet opening; a spring-loaded piston at least partially housed in the pump body and configured to pump fluid into and out of a pump chamber formed between the piston and the pump body; and a housing accommodating the piston and the pump body, the pump body being adapted to move axially relative to the housing. [12] A pump according to claim 11, wherein the pump body is arranged to move vertically downward when a pressure of the pump chamber exceeds a preload of a spring coupled between the pump body and the housing. [13] A pump according to claim 11 or 12, wherein the pump chamber is connected to an outlet chamber via the outlet opening and to a fluid supply via the one or more inlet openings. [14] A pump according to claim 13, wherein the piston is movable between a top dead center (TDC) position and a bottom dead center (BDC) position, wherein in the BDC position the one or more inlet openings are covered by the piston and the fluid connection between the fluid supply and the pump chamber is blocked, and wherein in the TDC position the one or more inlet openings are at least partially uncovered to establish a fluid connection between the fluid supply and the pump chamber. [15] A pump according to any one of claims 11 to 14, wherein the pump body is cylindrical and the housing is cylindrical, and wherein the one or more inlet openings are arranged in an annular recess of the pump body, the annular recess and the housing together forming a suction ring.

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