Engine lubrication system, lubrication fluid circulation system and fluid pressure regulation method

Abstract

A lubrication system for an internal combustion engine includes a fluid flow control device at an outlet side of a pump that regulates pressure conditions at the outlet side of the pump upstream of a lubrication circuit in the engine. The fluid flow control device is located in a recirculation path and opens in response to fluid pressure at an outlet of the pump exceeding a first threshold to allow fluid to flow from the outlet side of the pump back to an inlet side of the pump. The recirculation path includes a tuning device that maintains fluid pressure when engine speed is above the first threshold. In response to engine speed being above a second threshold, the tuning device restricts fluid flow in the recirculation path such that fluid pressure in the fluid flow path increases.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and filing date interest in U.S. Provisional Application Serial No. 63 / 183,836, filed May 4, 2021, which is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to internal combustion engines, and more specifically, but not exclusively, to pressure regulation of lubrication systems and lubrication fluid circulation systems for internal combustion engines. Background Technology

[0004] Generally, fluid flow control devices are already used in internal combustion engines to control the flow of oil and other fluids to provide lubrication and cooling for one or more engine components. For example, pressure regulators can be used to limit or prevent excessive pressure conditions in the lubrication circuit caused by the operation of the oil pump.

[0005] The size of the engine lubrication circuit is designed to provide the necessary pressure to maintain a continuous oil flow throughout the entire engine operating speed range, including engine overspeed conditions. Because centrifugal force acts on the oil flow through certain rotating components, the required pressure increases parabolically with engine speed. Therefore, the oil pressure required for non-overspeed engine operation is typically lower than the oil pressure required by rotating components under overspeed conditions.

[0006] Therefore, parasitic losses can increase throughout the engine's operating range because the regulated oil pressure is set to provide oil flow to meet the pressure requirements of engine overspeed conditions, which typically occur only for a small portion of the engine's operating time. Consequently, it is necessary to reduce parasitic losses during fluid flow for lubricating and cooling components in internal combustion engines. Summary of the Invention

[0007] This disclosure includes a unique system and method for regulating fluid pressure in a lubrication system of an internal combustion engine. The lubrication system includes a reservoir from which fluid is supplied by a pump to circulate through the lubrication system via a fluid flow path. The lubrication system includes a pressure regulator coupled downstream of the pump's outlet side to the fluid flow path.

[0008] In embodiments of this disclosure, the pressure regulator allows fluid to flow into a recirculation path that connects the outlet side of the pump to the inlet side of the pump in response to an engine speed exceeding a first threshold. The lubrication system also includes a tuning device in the recirculation path configured to maintain fluid flow in the recirculation path in response to an engine speed exceeding the first threshold, and to restrict fluid flow in the recirculation path in response to an engine speed exceeding a second threshold greater than the first threshold.

[0009] In another embodiment, a method for regulating fluid pressure in an internal combustion engine is provided. The method includes circulating fluid through a lubrication system of the internal combustion engine via a fluid flow path. The lubrication system includes a pump and a recirculation path, from which fluid is supplied, the recirculation path connecting the outlet side of the pump to the inlet side of the pump. The method further includes controlling the fluid flow through the recirculation path using a fluid flow control device in response to an engine speed exceeding a first threshold. The fluid flow control device is coupled downstream of the pump's outlet side to the fluid flow path. The method also includes maintaining fluid flow in the recirculation path in response to an engine speed exceeding the first threshold, and restricting fluid flow in the recirculation path in response to an engine speed exceeding a second threshold greater than the first threshold.

[0010] In another embodiment, the lubricating fluid circulation system includes a pump for circulating fluid through the lubrication system via a fluid flow path. The lubricating fluid circulation system includes a recirculation path having an inlet at a first end, an outlet at a second end opposite the first end, and a passage extending from the first end to the second end to allow fluid to flow from the inlet to the outlet. The lubricating fluid circulation system also includes a tuning device in the recirculation path. The tuning device is configured to control the amount of fluid flowing through the recirculation path such that the fluid pressure in the fluid flow path is maintained until a predetermined engine speed is reached. When the predetermined engine speed is exceeded, the tuning device limits the amount of fluid flowing through the recirculation path to increase the fluid pressure in the fluid flow path.

[0011] This invention is not intended to identify key or essential features of the claimed subject matter, nor is it intended to serve as an aid to limiting the scope of the claimed subject matter. Further embodiments, forms, objects, features, advantages, aspects, and benefits will become apparent from the following description and accompanying drawings. Attached Figure Description

[0012] The description herein refers to the accompanying drawings, which are used throughout several views. Similar reference numerals denote similar parts, and in the drawings:

[0013] Figure 1 This is a schematic block diagram of an exemplary lubrication system for an internal combustion engine according to an embodiment of the present disclosure.

[0014] Figure 2 It shows from Figure 1 A schematic block diagram of various possible locations of the tuning device in the recirculation path from the outlet side to the inlet side of the pump in the lubrication system.

[0015] Figure 3 This is a schematic diagram of one implementation scheme of the tuning device.

[0016] Figure 4This is a schematic diagram of another implementation of the tuning device.

[0017] Figure 5 This is a schematic diagram of another implementation of the tuning device.

[0018] Figure 6 This is a graph showing the pressure versus rotational speed of an exemplary operation of the tuning device in the recirculation path.

[0019] Figure 7 This is a flowchart illustrating an exemplary operation process for adjusting fluid pressure in a lubrication system. Detailed Implementation

[0020] To clearly, concisely, and accurately describe the illustrative embodiments of this disclosure, the manner and process of making and using this disclosure, and to enable the practice, making, and use of this disclosure, reference will now be made to certain exemplary embodiments, including those shown in the figures, and this disclosure will be described using specific language. However, it should be understood that this does not constitute any limitation on the scope of the invention, and that the invention includes and protects such changes, modifications, and further applications of the exemplary embodiments that would occur to those skilled in the art.

[0021] refer to Figures 1 to 7 This disclosure relates to a lubrication system 100 for an internal combustion engine 102. In one embodiment, the lubrication system 100 includes a reservoir 118, a fluid flow path 114, a pressure regulator 106, and a tuning device 122. Fluid is supplied from the reservoir 118 by a pump to circulate through the lubrication system 100 via the fluid flow path 114. The pressure regulator 106 is located downstream of the pump and is configured to allow fluid to flow through a recirculation path 120 in response to an engine speed exceeding a first threshold. The tuning device 122 is located in the recirculation path 120.

[0022] In one embodiment, the lubrication system 100 includes a lubricating fluid circulation system 101. The lubricating fluid circulation system 101 includes a pump 108, a recirculation path 120, and a tuning device 122. The tuning device 122 is configured to control the amount of fluid flowing through the recirculation path 120 and maintain the fluid pressure in the fluid flow path 114 until a predetermined engine speed is reached. In response to exceeding the predetermined engine speed, the tuning device 122 increases the fluid pressure in the fluid flow path 114 by limiting the amount of fluid flowing through the recirculation path 120.

[0023] In one embodiment, the lubrication system 100 includes a fluid flow control device 104 configured to regulate fluid flow and / or fluid pressure within the lubrication system 100. The lubrication system 100 and / or the lubrication fluid circulation system 101 include a tuning device 122, such as an orifice, in a recirculation path 120 of the lubrication fluid pump 108, said tuning device being in fluid communication with a pressure regulator 106 (such as a pressure regulating valve). The tuning device 122 is configured to restrict fluid flow above an engine speed threshold during engine operation to increase fluid pressure in the system 100. In an exemplary embodiment, the tuning device 122 is configured to block or restrict fluid flow through the recirculation path 120 in response to an engine speed exceeding an engine speed threshold associated with an engine overspeed condition, thereby increasing fluid pressure in the fluid flow path 114 to maintain fluid flow to engine components during overspeed conditions.

[0024] In one embodiment, the lubrication system 100 includes a reservoir 118 from which fluid is supplied by a pump 108 to circulate through the lubrication system 100 via a fluid flow path 114. The lubrication system 100 includes a pressure regulator 106 located downstream of the outlet side of the pump 108. The pressure regulator 106 may be a pressure regulating valve configured to allow fluid flow through a recirculation path 120 in response to an engine speed exceeding a first threshold. The recirculation path 120 connects the outlet side of the pump 108 to the inlet side of the pump 108. A tuning device 122 is located in the recirculation path 120. The tuning device 122 is configured not to restrict fluid flow in the recirculation path 120 in response to an engine speed exceeding the first threshold. The tuning device 122 is also configured to restrict fluid flow in the recirculation path 120 in response to an engine speed exceeding a second threshold greater than the first threshold.

[0025] In one embodiment, the lubricating fluid circulation system 101 includes a pump 108 for circulating fluid through the lubrication system 100 via a fluid flow path 114. The lubricating fluid circulation system 101 includes a recirculation path 120 having an inlet 120a at a first end, an outlet 120b at a second end opposite the first end, and a passage 120c extending from the first end to the second end to allow fluid to flow from the inlet 120a to the outlet 120b. The lubricating fluid circulation system 101 includes a tuning device 122 in the recirculation path 120. The tuning device 122 is configured to control the amount of fluid flowing through the recirculation path 120 and maintain the fluid pressure in the fluid flow path 114 until a predetermined engine speed is reached. In response to exceeding the predetermined engine speed, the tuning device 122 increases the fluid pressure in the fluid flow path 114 by limiting the amount of fluid flowing through the recirculation path 120.

[0026] In one embodiment, a method includes circulating fluid through a lubrication system 100 of an internal combustion engine 102 via a fluid flow path 114. The lubrication system 100 includes a pump 108 and a recirculation path 120, through which fluid is supplied from the pump into the fluid flow path 114, the recirculation path connecting the outlet side of the pump 108 to the inlet side of the pump 108. The method includes controlling the fluid flow through the recirculation path 120 using a fluid flow control device 104 in response to an engine speed exceeding a first threshold. The fluid flow control device 104 is coupled downstream of the outlet side of the pump 108 to the fluid flow path 114. The method includes maintaining a substantially constant pressure in the fluid flow path 114 using the fluid flow in the recirculation path 120 in response to an engine speed exceeding the first threshold, and restricting the fluid flow in the recirculation path 120 in response to an engine speed exceeding a second threshold greater than the first threshold.

[0027] exist Figure 1 In this system, lubrication system 100 includes a fluid control device 104. The fluid flow control device 104 may be, for example, a pressure regulator 106 located downstream of lubrication fluid pump 108 and upstream of lubrication fluid filter 110. Lubrication system 100 also includes oil passages 112 for supplying lubricating fluid in fluid flow path 114 to a plurality of engine components 116 and / or other oil passages (not shown) for distribution around various components and locations relative to engine 102. Lubricating fluid may circulate through lubrication system 100 via lubrication fluid circulation system 101.

[0028] The lubricating fluid is returned to a reservoir 118, such as an oil pan, at or near the inlet or suction side of pump 108. A recirculation path 120 is provided in the lubrication system 100 and / or the lubricating fluid circulation system 101 to allow fluid flow therein. The recirculation path 120 can extend from the outlet of pump 108 to the inlet of pump 108. In an exemplary embodiment, the lubrication system 100 and / or the lubricating fluid circulation system 101 includes a tuning device 122, such as an orifice 156 in the recirculation path 120. Figure 5 ).

[0029] In embodiments of this disclosure, tuning device 122 is coupled in the flow path of pressure regulator 106. Tuning device 122 is configured to not restrict fluid flow in recirculation path 120 in response to engine speed exceeding a first engine speed threshold. For example, the tuning device allows the amount of fluid flow in recirculation path 120 to provide a nominally regulated, substantially constant fluid pressure at pump 108 outlet during normal engine operation above the first engine speed threshold. Tuning device 122 may be configured such that the fluid pressure in fluid flow path 114 is maintained at a constant or substantially constant pressure within an acceptable range above and / or below a target pressure in the engine speed range below engine overspeed conditions. In one embodiment, maintaining the fluid pressure in fluid flow path 114 includes preventing the fluid pressure in fluid flow path 114 from increasing or decreasing proportionally with increasing or decreasing engine speed when above the first engine speed threshold.

[0030] For example, below a first engine speed threshold, no fluid flows through pressure regulator 106, thus recirculation path 120 is closed. When engine speed increases above the first engine speed threshold, pressure regulator 106 opens and fluid flow output at pump 108 can vary, allowing pressure in fluid flow path 114 to remain substantially constant without increasing in proportion to the increase in engine speed. When engine speed reaches a second engine speed threshold (such as in an engine overspeed condition), tuning device 122 restricts or prevents fluid flow to or out of pressure regulator 106 in recirculation path 120, such that fluid pressure in fluid flow path 114 increases proportionally to engine speed, while fluid continues to flow at a sufficient rate to provide the necessary lubrication to engine components 116 during engine overspeed conditions.

[0031] The tuning device 122 reduces parasitic losses by allowing the nominal regulating pressure in the fluid flow path 114 between the first engine speed threshold and the second engine speed threshold to be lower than the pressure under overspeed conditions. This reduces the power required to drive the lubrication fluid pump 108 during the most common engine operating conditions, which typically occur below the second engine speed threshold, while also providing the required fluid flow through the oil passage 112 to the fluid flow path 114 at a pressure higher than the nominal regulating pressure during engine overspeed conditions.

[0032] It should be understood that not all components or aspects of the lubrication system are shown, and system 100 can be configured according to any known engine fluid lubrication system incorporating the fluid flow control device 104 of this disclosure. Furthermore, while the lubricating fluid may be engine oil according to one embodiment, other types of fluids and fluid circuits in which the fluid flow control device 104 may be employed are also contemplated.

[0033] Figure 2 It shows from Figure 1 A schematic block diagram of various possible locations of the tuning device 122 in the recirculation path 120 from the outlet to the inlet side of the pump 108 of the lubrication system 100 and / or the lubrication fluid circulation system 101. Figure 2 In this diagram, various possible positions of the tuning device 122 are represented by tuning device positions 122a, 122b, and 122c. In one exemplary embodiment, the tuning device 122 is positioned in the recirculation path 120 between the outlet side of the pump 108 and the pressure regulator 106, as shown in position 122a. In another exemplary embodiment, the tuning device 122 is positioned in the recirculation path 120 between the inlet side of the pump 108 and the pressure regulator 106. For example, the tuning device 122 may be positioned at the outlet of the pressure regulator 106, as shown in position 122b. Figure 2 In this embodiment, the suction pipe 124 (e.g., the inlet circuit upstream of pump 108) is provided in the lubrication system 100 and / or the lubricating fluid circulation system 101. Therefore, in another exemplary embodiment, the tuning device 122 is provided at the inlet of the suction pipe 124, as shown in position 122c.

[0034] It should also be understood that another exemplary embodiment of the lubrication system 100 and / or the lubricating fluid circulation system 101 is configured with a tuning device 122 formed within the pressure regulator 106. For example, as Figure 3 As shown, the tuning device 122 can be provided by the geometry of a slide valve 134 of the pressure regulator 106, which is configured to restrict fluid flow when the engine speed is above a second engine speed threshold. The slide valve 134, shown in cross-section, includes a configuration that blocks access to the inlet 130 of the pressure regulator 106 in a closed configuration, as shown by the dashed slide valve 134. In an open configuration, the slide valve 134 shifts to open the inlet 130, but provides a flow path 136 of limited size relative to the outlet 132, such that flow through the recirculation path 120 is restricted during engine overspeed conditions.

[0035] The size of the regulated recirculation path 120 provided by the slide valve 134 is designed to maintain the fluid pressure output by the pump 108 by allowing unrestricted fluid flow in the recirculation path 120 between a first engine speed threshold and a second engine speed threshold. Restricting fluid flow in the recirculation path 120 causes the pressure in the fluid flow path 114 to increase during engine operation at speeds above the second engine speed threshold.

[0036] In one embodiment, the pressure regulator 106 is configured with a tuning device 122 that limits the stroke of the plunger in the pressure regulator 106. For example, as Figure 4As shown, the tuning device 122 can be provided by limiting the stroke of the slide valve 140 in the pressure regulator 106 to restrict fluid flow when the engine speed exceeds a second engine speed threshold. The slide valve 140 includes a closed position blocking the inlet 130 of the pressure regulator 106, as shown by the dashed line. In the open position, the slide valve is displaced to no longer block the inlet 130. However, the stroke of the plunger 142 of the slide valve 140 is limited such that the slide valve 140 partially blocks the outlet 132 via its protrusion 134. Therefore, during engine overspeed conditions, when the inlet 130 is open, fluid flow through the recirculation path 120 is limited by partially blocking the outlet 132 via the slide valve 140.

[0037] exist Figures 3 to 4 In one implementation, the spool valve geometry and / or plunger stroke limiter restrict the size of the flow path through the pressure regulator 106. The size of the recirculation path is adjusted such that the fluid pressure output by the pump 108 is maintained by allowing fluid flow in the recirculation path 120 without restriction between a first engine speed threshold and a second engine speed threshold. At higher engine speeds, the spool valve geometry or positioning restricts fluid flow in the recirculation path 120, causing the pressure in the fluid flow path 114 to increase when the engine speed is above the second engine speed threshold.

[0038] In another embodiment, pressure regulator 106 is provided with a non-linear regulator spring that allows the fluid pressure output by pump 108 to remain substantially constant above a first engine speed threshold, rather than continuing to increase with engine speed. The non-linear spring adjusts the flow path size to maintain the fluid pressure output by pump 108 by allowing unrestricted fluid flow in recirculation path 120 between the first and second engine speed thresholds. At higher speeds, the non-linear regulator spring provides increased resistance to valve opening, restricting fluid flow in recirculation path 120, and the pressure in fluid flow path 114 increases when engine speed exceeds the second engine speed threshold.

[0039] exist Figure 5In another embodiment shown, the tuning device 122 is an orifice 156 in the recirculation path 120. For example, the orifice 156 may be provided by an opening extending through a body 154 positioned in and partially blocking the channel 120c. The body 154 may be located anywhere in the channel 120c, such as at the outlet 132 of the pressure regulator 106 or other suitable locations as described herein. The pressure regulator 106 includes a first position and a second position, in which the valve body 150 blocks the inlet 130, and in which the inlet 130 and outlet 132 are open. However, when the engine speed is above a second engine speed threshold, fluid flow through the outlet 132 is restricted by the orifice 156.

[0040] Figure 6 This is a schematic diagram illustrating exemplary operation of the lubrication system 100 and / or the lubrication fluid circulation system 101, wherein the tuning device 122 is located in the recirculation path 120. In operation, the pressure regulator 106 is initially closed, so there is no fluid flow in the recirculation path 120. Then, when the engine speed reaches a first engine speed threshold 126, the pressure regulator 106 opens. The amount of fluid recirculated in the recirculation path 120 through the pressure regulator 106 and the tuning device 122 allows the fluid pressure output by the pump 108 to remain substantially constant above the first engine speed threshold 126, and until a second engine speed threshold 128 is reached.

[0041] The second engine speed threshold 128 can be associated with, for example, an engine overspeed condition. When the engine speed exceeds the second engine speed threshold 128, the tuning device 122 restricts fluid flow in the recirculation path 120. For example, in response to the engine speed exceeding the second engine speed threshold 128, the tuning device 122 blocks fluid flow, which increases the fluid pressure output by the pump 108 because less fluid can be recirculated than is required to maintain a constant fluid pressure. However, the tuning device 122 is configured with a predefined opening area in the recirculation path 120, which is configured to bypass the amount of fluid flow required to maintain a constant fluid pressure between the first engine speed threshold 126 and the second engine speed threshold 128. In one embodiment, the first and second engine speed thresholds are associated with normal or non-overspeed engine operating conditions.

[0042] Figure 7This is a flowchart illustrating an exemplary operational process 300 for regulating fluid pressure in lubrication system 100 and / or lubrication fluid circulation system 101. Process 300 begins with a start operation 302, such as an engine start event. Process 300 continues at operation 304 to circulate fluid through lubrication system 100 and / or lubrication fluid circulation system 101. Process 300 continues from operation 304 to operation 306 to control fluid flow through recirculation path 120 using pressure regulator 106 in response to the engine exceeding a first threshold.

[0043] Process 300 continues from operation 306 to operation 308. In response to the engine speed exceeding a first threshold and the pressure being less than a second pressure, operation 308 maintains the fluid flow from pump 108 in fluid flow path 114 at a substantially constant pressure. As discussed above, the size of the tuning device 122 in recirculation path 120 is designed to provide the amount of recirculated flow in recirculation path 120 based on engine speed, which allows the oil passage pressure in fluid flow path 114 to remain substantially constant.

[0044] Process 300 continues from operation 308 to operation 310. Operation 310, in response to an engine speed exceeding a second threshold greater than the first threshold, utilizes tuning device 122 to restrict fluid flow in recirculation path 120. Consequently, the pressure in fluid flow path 114 increases from a substantially constant pressure generated below the second engine speed threshold. Pumping losses at engine speeds between the first and second engine speed thresholds are reduced compared to systems without tuning device 122 (such as systems configured with recirculation paths sized to generate constant pressure in fluid path 114 at all engine speeds, including engine overspeed conditions above the first engine speed threshold).

[0045] According to the exemplary embodiments and implementations described above, a tuning device 122, such as a tuning orifice or other tuning device, can be disposed in the recirculation path 120 leading to the lubrication pump 108. The tuning device 122 is sized to allow the oil passage pressure to increase above the nominal or nominally desired oil passage pressure at a certain engine speed threshold in order to provide lubricating fluid at the increased pressure. The tuning device 122 does not require reconfiguration of the recirculation path 120 in the engine 102 or resizing to provide the desired pressure distribution in the fluid flow path 114 across the entire engine speed range when the recirculation path 120 is open.

[0046] Further written descriptions of several exemplary embodiments will now be provided. One exemplary embodiment is a lubrication system for an internal combustion engine. The lubrication system includes: a fluid flow path and a reservoir, from which fluid is supplied by a pump to circulate through the lubrication system via the fluid flow path; and a pressure regulator downstream of the pump's outlet side. The pressure regulator allows fluid flow through a recirculation path by connecting the pump's outlet side to the pump's inlet side in response to an engine speed exceeding a first threshold. The lubrication system also includes a tuning device in the recirculation path, configured to not restrict fluid flow in the recirculation path in response to an engine speed exceeding the first threshold, and to restrict fluid flow in the recirculation path in response to an engine speed exceeding a second threshold greater than the first threshold.

[0047] In some embodiments of the aforementioned system, the fluid flow path is pressurized at a constant pressure between a first threshold and a second threshold. In some embodiments, the fluid flow path is pressurized with a fluid pressure that gradually increases as the engine speed increases above the second threshold.

[0048] In some embodiments, the tuning device is an orifice located in the recirculation path between the pump's outlet side and the pressure regulator. In some embodiments, the tuning device is an orifice located in the recirculation path between the pump's inlet side and the pressure regulator. In some embodiments, the orifice is located at the outlet of the pressure regulator. In some embodiments, the orifice is located at the pump's inlet.

[0049] In some embodiments, the tuning device is the spool geometry of the pressure regulator. In some embodiments, the tuning device is a plunger stroke limiter of the pressure regulator. In some embodiments, the pressure regulator closes when the engine speed is below a first threshold.

[0050] Another exemplary embodiment is a method for regulating fluid pressure in an internal combustion engine. The method includes circulating fluid through a lubrication system of the internal combustion engine via a fluid flow path. The lubrication system includes a pump and a recirculation path, through which fluid is supplied from the pump and the recirculation path connects the outlet side of the pump to the inlet side of the pump. The method further includes controlling the fluid flow through the recirculation path using a fluid flow control device in response to an engine speed exceeding a first threshold. The fluid flow control device is located downstream of the pump's outlet side in the recirculation path. The method also includes maintaining fluid flow in the recirculation path in response to an engine speed exceeding the first threshold, and restricting fluid flow in the recirculation path in response to an engine speed exceeding a second threshold greater than the first threshold.

[0051] In one embodiment of the aforementioned method, maintaining fluid flow in the recirculation path includes keeping the pressure in the fluid flow path substantially constant between a first threshold and a second threshold. In one embodiment, restricting fluid flow includes increasing the fluid pressure in the fluid flow path when the engine speed is above the second threshold.

[0052] In one embodiment of the method, restricting fluid flow includes restricting fluid flow through an orifice located between the pump's outlet side and the fluid flow control device. In another embodiment, restricting fluid flow includes restricting fluid flow through an orifice located between the pump's inlet side and the fluid flow control device.

[0053] In one embodiment, restricting fluid flow in the recirculation path includes using a pressure regulator to restrict fluid flow in response to an engine speed exceeding a second threshold. In another embodiment, the method includes shutting off a fluid flow control device when the engine speed is below a first threshold to prevent fluid from flowing through the recirculation path.

[0054] Another exemplary embodiment is a lubricating fluid recirculation system for an internal combustion engine. The lubricating fluid recirculation system includes a pump for circulating fluid through the lubrication system via a fluid flow path. The lubricating fluid recirculation system includes a recirculation path having an inlet at a first end, an outlet at a second end opposite the first end, and a passage extending from the first end to the second end to allow fluid to flow from the inlet to the outlet. The lubricating fluid recirculation system also includes a tuning device in the recirculation path. The tuning device is configured to control the amount of fluid flowing through the recirculation path and maintain the fluid pressure in the fluid flow path until a predetermined engine speed is reached. The tuning device increases the fluid pressure in the fluid flow path by limiting the amount of fluid flowing through the recirculation path in response to exceeding the predetermined engine speed.

[0055] In one embodiment, the recirculation path includes a pressure regulator that prevents fluid from flowing through the recirculation path when the engine speed is below a first threshold. The pressure regulator is configured to open when the engine speed is above the first threshold to allow fluid to flow through the recirculation path.

[0056] While illustrative embodiments of the present disclosure have been shown and described in detail in the accompanying drawings and the foregoing description, these drawings and description are to be regarded as illustrative rather than restrictive in nature. It should be understood that only certain exemplary embodiments are shown and described, and protection is intended for all changes and modifications within the spirit of the claimed invention. It should be understood that although the use of words such as preferred, preferably, or more preferably in the above description indicates that such described features may be more desirable, but may not be necessary, and embodiments lacking said features are conceivable within the scope of the invention, defined by the appended claims. When reading the claims, it is not intended that the claims be limited to only one item when words such as “a,” “an,” “at least one,” or “at least a portion” are used, unless there is an explicit statement to the contrary in the claims. When the language “at least a portion” and / or “a portion” is used, the item may include a portion and / or the entire item, unless there is an explicit statement to the contrary.

Claims

1. A lubrication system for an internal combustion engine, the lubrication system comprising: A fluid flow path and a reservoir, wherein fluid is supplied from the reservoir by a pump to circulate through the lubrication system via the fluid flow path; A pressure regulator downstream of the pump's outlet side is configured to allow fluid to flow through a recirculation path in response to an engine speed exceeding a first threshold, the recirculation path connecting the pump's outlet side to the pump's inlet side. as well as The tuning device in the recirculation path allows fluid flowing from the outlet side of the pump to the inlet side of the pump to pass through the tuning device in the recirculation path. The tuning device is configured to: In response to the engine speed exceeding the first threshold, the flow of the fluid through the tuning device in the recirculation path is not restricted; as well as In response to the engine speed exceeding a second threshold greater than the first threshold, the flow of the fluid through the tuning device in the recirculation path is restricted.

2. The lubrication system of claim 1, wherein the fluid flow path is pressurized at a constant fluid pressure between the first threshold and the second threshold.

3. The lubrication system of claim 2, wherein the fluid flow path is pressurized with a fluid pressure that gradually increases as the engine speed increases above the second threshold.

4. The lubrication system of claim 1, wherein the tuning device is an orifice located in the recirculation path between the outlet side of the pump and the pressure regulator.

5. The lubrication system of claim 1, wherein the tuning device is an orifice located in the recirculation path between the inlet side of the pump and the pressure regulator.

6. The lubrication system of claim 5, wherein the orifice is located at the outlet of the pressure regulator.

7. The lubrication system of claim 5, wherein the orifice is located at the inlet of the pump.

8. The lubrication system of claim 1, wherein the tuning device is a slide valve in the pressure regulator.

9. The lubrication system of claim 1, wherein the tuning device is a plunger stroke limiter in the pressure regulator.

10. The lubrication system of claim 1, wherein the pressure regulator is closed when the engine speed is less than the first threshold.

11. A method for regulating fluid pressure in an internal combustion engine, the method comprising: Fluid is circulated through the lubrication system of the internal combustion engine via a fluid flow path, the lubrication system including a pump and a recirculation path, the fluid being supplied from the pump into the fluid flow path, the recirculation path connecting the outlet side of the pump to the inlet side of the pump, and the fluid flow in the recirculation path passing through a flow control device and a tuning device. In response to an engine speed exceeding a first threshold, a fluid flow control device is used to control the fluid flow through the recirculation path, the fluid flow control device being located downstream of the outlet side of the pump in the recirculation path; In response to the engine speed exceeding the first threshold, the pressure in the fluid flow path is maintained constant by utilizing the fluid flow in the recirculation path; as well as In response to the engine speed exceeding a second threshold greater than the first threshold, the fluid flow through the tuning device in the recirculation path is restricted.

12. The method of claim 11, wherein maintaining a constant pressure in the fluid flow path includes maintaining the pressure constant between the first threshold and the second threshold.

13. The method of claim 12, wherein restricting the fluid flow includes increasing the fluid pressure in the fluid flow path when the engine speed is above the second threshold.

14. The method of claim 11, wherein restricting the fluid flow includes restricting the fluid flow through an orifice located between the outlet side of the pump and the fluid flow control device.

15. The method of claim 11, wherein restricting the fluid flow includes restricting the fluid flow through an orifice located between the inlet side of the pump and the fluid flow control device.

16. The method of claim 11, wherein limiting the fluid flow in the recirculation path includes limiting the fluid flow in response to an engine overspeed condition corresponding to the second threshold.

17. The method of claim 11, wherein limiting the fluid flow in the recirculation path includes limiting the fluid flow using a pressure regulator that limits the fluid flow in the recirculation path in response to the engine speed exceeding the second threshold.

18. The method of claim 11, further comprising shutting off the fluid flow control device when the engine speed is less than the first threshold to prevent fluid from flowing through the recirculation path.

19. A lubricating fluid circulation system for an internal combustion engine, the lubricating fluid circulation system comprising: Pump, the pump being used to circulate fluid through a lubrication system via a fluid flow path; A recirculation path having an inlet at a first end, an outlet at a second end opposite to the first end, and a channel extending from the first end to the second end to allow the fluid to flow from the inlet to the outlet; as well as The tuning device in the recirculation path allows fluid flowing from the outlet side of the pump to the inlet side of the pump to flow through the tuning device in the recirculation path. The tuning device is configured to control the amount of fluid flowing through the tuning device in the recirculation path and maintain the fluid pressure in the fluid flow path until a predetermined speed of the internal combustion engine is reached. The tuning device increases the fluid pressure in the fluid flow path by limiting the amount of fluid flowing through the tuning device in response to exceeding the predetermined speed of the internal combustion engine.

20. The lubricating fluid circulation system of claim 19, wherein the recirculation path includes a pressure regulator that prevents fluid from flowing through the recirculation path when the engine speed is below a first threshold, the pressure regulator being configured to open to allow fluid to flow through the recirculation path when the engine speed is above the first threshold.

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