WO2019111271A1

WO2019111271A1 - Variable pressure oil pump

Info

Publication number: WO2019111271A1
Application number: PCT/IN2018/050216
Authority: WO
Inventors: J. Suresh KUMAR; R. Sivanantham
Original assignee: Ucal Fuel Systems Limited
Priority date: 2017-12-08
Filing date: 2018-04-13
Publication date: 2019-06-13

Abstract

A Variable Pressure Oil Pump (VPOP) system (100) is used for delivering required amount of working fluid to the engine based on predetermined engine speed conditions to improve the engine fuel efficiency. The VPOP system (100) has an inlet passage (30) for suctioning of oil from the oil sump (102) and has a delivery passage (31) for delivering of the oil to the engine. The VPOP system (100) further includes two return passages (32, 33) for returning the oil back to the inlet passage (30) and a relief passage (34) for returning the oil back to the oil sump (102) at different engine speed conditions. A hydraulic dual valve assembly (50) incorporated into the VPOP system (100) regulates the pressure developed in the delivery passage (31) and also controls the amount of quantity delivered to the engine lubrication circuits (101) at different speed conditions.

Description

VARIABLE PRESSURE OIL PUMP

FIELD OF THE INVENTION

The present invention relates to a Variable Pressure Oil Pump (VPOP) and more specifically, it relates to a system for Variable Pressure Oil Pump for regulating the pressure developed in the VPOP and varying the quantity of oil delivered to the engine according to engine speed and engine demand conditions.

BACKGROUND

An oil pump system is used in vehicles for lubrication of the engine parts and related systems by pressurizing the oil in the oil sump and delivering it to the lubrication circuits. Conventional oil pump system has a rotary type oil pump which is directly connected to the engine crankshaft. Therefore, the quantity of oil delivered to the engine varies linearly with the engine speed and is not dependent of engine demand.

The conventional oil pump system consists of an inner rotor which is directly coupled with the engine crankshaft and an outer rotor mounted around the inner rotor. The number of teeth in the inner rotor is one tooth less than the outer rotor. When the engine starts, the inner rotor starts to rotate which moves the outer rotor and draws oil from the oil sump and delivers it to the engine lubrication circuits. When the volume between the inner and outer rotor teeth gradually increases, suction of oil from the oil sump takes place and when the volume between inner and outer rotor reduces, the delivery of oil happens. Thus the pump system delivers oil quantity linearly with engine speed. Normally, gerotor type rotary pumps are widely used in the internal combustion engines.

The above system delivers oil to the engine lubrication circuits regardless of the demand at the engine. More specifically, during medium and high speed conditions, the above system supplies excess amount of oil to the engine which leads to high power consumption. The above system also develops higher delivery pressure during medium and high speed conditions.

Thus, a Variable Pressure Oil Pump (VPOP) has been developed to overcome the above problems of the conventional rotary type oil pumps. OBJECT OF THE INVENTION

It is the principal object of the present invention to provide a Variable Pressure Oil Pump (VPOP).

It is another object of the present invention to provide a VPOP system to control the oil quantity delivered to the engine for predetermined engine operating conditions and speeds.

It is another object of the present invention to reduce power losses in the engine when delivering excess quantity of oil to the engine at high speed conditions.

SUMMARY OF THE INVENTION

The present invention discloses a system to address the above mentioned problems and to control the oil quantity delivered to engine for specific operating conditions and speed. The VPOP system delivers oil quantity linearly with speed at low speed conditions and delivers only sufficient amount of oil quantity at medium speed conditions and also reduces the excess supply of oil to the engine at high speed conditions.

According to an embodiment of the present invention, a Variable Pressure Oil Pump (VPOP) system for internal combustion engine comprising an inlet passage fluidically connected to an oil sump, a delivery passage fluidically connected to the engine lubrication circuits, a hydraulic dual valve assembly operating at predetermined engine speed conditions, a first return passage connected to the inlet passage through the hydraulic dual valve assembly, a second return passage connected to the inlet passage and a relief passage in the hydraulic dual valve assembly for relieving the pressure developed in the delivery passage.

According to an embodiment of the present invention, the hydraulic dual valve assembly includes a primary valve resting on a primary spring member, a secondary valve resting on a secondary spring member, a first inlet port for providing inlet to the first return passage, a second inlet port for providing inlet to the second return passage, a shutoff port for providing inlet to the relief passage, a port connecting the first return passage to the inlet passage and a port connecting the second return passage to the inlet passage. According to an embodiment of the present invention, the primary spring member connects the primary valve and the secondary valve.

According to an embodiment of the present invention, the primary valve floats inside the hydraulic dual valve assembly.

According to an embodiment of the present invention, the hydraulic dual value assembly regulates the flow of oil from the inlet passage to the delivery passage at medium and high speed conditions.

According to an embodiment of the present invention, the hydraulic dual valve assembly allows some quantity of oil to return from the delivery passage to the inlet passage through the first return passage at transition from lower speed to first range of medium speed conditions.

According to an embodiment of the present invention, the hydraulic dual valve assembly allows more quantity of oil to return from the delivery passage to the inlet passage through the first return passage at first range of medium speed conditions.

According to an embodiment of the present invention, the hydraulic dual valve assembly closes the port and disconnects the first return passage to the inlet passage at second range of medium speed conditions.

According to an embodiment of the present invention, the hydraulic dual valve assembly opens the second inlet port to allow some quantity of oil to return back from the delivery passage to the inlet passage through the second return passage at high speed conditions.

According to an embodiment of the present invention, the hydraulic dual valve assembly opens the shutoff port to return excess quantity of oil to the oil sump through the relief passage and through the second return passage to inlet passage at shutoff limit and/or very high speed conditions.

According to an embodiment of the present invention, the secondary spring member is connected to a retainer member fitted at the bottom of the hydraulic dual valve assembly. BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic layout of a VPOP system according to an embodiment of present invention.

FIG.2 is a schematic layout of first operational mode of the VPOP system at low speed conditions.

FIG.3 is a schematic layout of transitional operational mode of the VPOP system during transition from lower speed to first range of medium speed conditions.

FIG.4 is a schematic layout of second operational mode of the VPOP system at first range of medium speed conditions.

FIG. 5 is a schematic layout of third operational mode of the VPOP system at second range of medium speed conditions.

FIG. 6 is a schematic layout of fourth operational mode of the VPOP system at high speed conditions.

FIG. 7 is schematic layout of fifth operational mode of the VPOP system during shutoff conditions.

FIG. 8 is a graph showing the relationship between delivered oil quantity and engine speed according to an embodiment of present invention.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. Each embodiment described in this disclosure is provided merely as an example or illustration of the present invention, and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. The embodiment provided herein is for the purpose of filing the present complete specification; however, further embodiments within this disclosure are possible and shall/may be covered in the complete specification.

FIG. 1 is a schematic layout of a VPOP system (100) according to an embodiment of the present invention. The VPOP system (100) has an inlet passage (30) for suctioning of the oil from an oil sump (102) and has a delivery passage (31) for delivering of oil to engine lubrication circuits (101). The VPOP system (100) also has a first return passage (32) connected to the inlet passage (30) through a hydraulic dual valve assembly (50) and a second return passage (33) for returning of the oil back to the inlet passage (30) at medium and high speed conditions. The VPOP system (100) also has a relief passage (34) which relieves the high pressure developed in the VPOP system (100) by returning the oil back to the oil sump (102) during shutoff conditions. The VPOP system (100) further comprises of an inner rotor (20) having an external gear tooth (21) and an outer rotor (22) having an internal gear tooth (23). The inner rotor (20) has one teeth less than the outer rotor (22). The external gear tooth (21) of the inner rotor (20) and the internal gear tooth (23) of the outer rotor (22) are defined by trochoidal curve. The hydraulic dual valve assembly (50) is integrated with the VPOP system (100) which operates based on the outlet pressure developed in the VPOP system (100).

The hydraulic dual valve assembly (50) has a primary valve (51) placed on a primary spring member (53) and a secondary valve (52) placed on a secondary spring member (54). The primary spring member (53) connects the primary valve (51) and the secondary valve (52). The hydraulic dual valve assembly (50) has a first inlet port (55) which acts as an inlet of the first return passage (32) connecting to the inlet passage (30) through port (58) and port (59). The second inlet port (56) acts as an inlet of the second return passage (33) connecting to the inlet passage (30). The shutoff port (57) allows the oil to flow back to the oil sump (102) during the shutoff conditions. The primary valve (51) and secondary valve (52) may be of any shape, i.e., it may be a ball valve or cylindrical valve or the like. The primary valve (51) starts floating in the hydraulic dual valve assembly (50) during the high operating conditions. Thus the primary valve (51) gives greater stability in lower and medium speed conditions. The secondary spring member (54) is placed under the secondary valve (52) and finally retainer member (60) is fitted at the bottom end of the hydraulic dual valve assembly (50). The length of the secondary valve (52) determines the opening and closing of the ports (55, 56, 57) formed in the hydraulic dual valve assembly (50). The hydraulic dual valve assembly unit (50) of the present invention regulates the outlet pressure developed in the VPOP system (100) and also varies the amount of oil quantity supplied to the engine based on engine speed.

The operation of the present invention is explained through FIGS (2-7).

FIG.2 is a schematic layout of first operational mode of the VPOP system (100) at low speed conditions. According to an embodiment of the present invention, when the engine initially starts, the inner rotor (20) which is directly coupled with the crankshaft of the engine starts to rotate at a lower speed. When the inner rotor (20) rotates, the space between the external gear tooth (21) and the internal gear tooth (23) increases gradually which causes suction of oil from the oil sump (102) through the inlet passage (30). When the volume between the external gear tooth (21) and internal gear tooth (23) starts decreasing, the supply of oil to the delivery passage (31) takes place. During this condition, the pressure developed in the delivery passage (31) is less than the force exerted by primary spring member (53) on the primary valve (51). Hence, there is no movement of the primary valve (51) of the hydraulic valve assembly (50). Thus, the oil flows linearly from the inlet passage (30) to the delivery passage (31) with the engine speed. This is explained as a straight line OA in the graph shown in FIG. 8. Thus at lower speed conditions, the quantity of oil delivered to the engine lubrication circuits (101) varies linearly with the engine speed.

FIG.3 is a schematic layout of transitional operational mode of the VPOP system (100) during transition from lower speed to first range of medium speed conditions. According to an embodiment of the present invention, when the speed of an inner rotor (20) reaches predetermined speed Nl, that is, transition from lower speed to first medium speed range, the pressure developed in the delivery passage (31) overcomes the spring force of the primary spring member (53). Thus, the primary valve (51) starts to move in the direction Al which allows some quantity of oil from the delivery passage (31) to return to the inlet passage (30) through the first return passage (32). This reduces the oil quantity delivered to the engine lubrication circuits (101) shown by line A-B in FIG. 8.

FIG. 4 is a second operational mode schematic layout of the VPOP system (100) at first range of medium speed condition. When the speed of the inner rotor (20) exceeds the predetermined speed N2 and pressure developed in the delivery passage (31) exceeds the primary spring member (53) force, the primary valve (51) completely opens and more amount of oil from the delivery passage (31) is returned back to the inlet passage (30) through the first return passage (32) through the first inlet port (55). Therefore, up to the medium speed range N3, only sufficient amount of oil is supplied to the engine lubrication circuits (101). This is shown by a line B-C in FIG.8. Hence the quantity of oil delivered to the engine lubrication circuits (101) reduces during the first medium range.

FIG. 5 is a schematic layout of third operational mode of the VPOP system (100) at second range of medium speed conditions. According to an embodiment of the present invention, when the speed of the inner rotor (20) reaches the predetermined speed N3 that is, at the second range of medium speed conditions, the pressure developed in the delivery passage (31) is further greater than the spring force of the secondary spring member (54), the secondary valve (52) moves further in the direction A1 which closes the port (58). This disconnects the first return passage (32) to the inlet passage (30). Hence, the quantity of oil delivered to the engine lubrication circuits rapidly rises which is shown by line C-D in FIG. 8 .Thus, after reaching the speed N3, the quantity of oil delivered to the engine varies linearly with the engine speed. This continues up to the predetermined speed N4. This is shown by a line D-E in FIG. 8.

FIG. 6 is a schematic layout of fourth operational mode of the VPOP system (100) at high speed conditions. According to an embodiment of the present invention, when the speed of the inner rotor (20) exceeds the predetermined speed N4, that is, high speed conditions and when the pressure developed in the delivery passage (31) is greater than the spring force of the secondary spring member (54), the secondary valve (52) moves in the direction Al which opens the second inlet port (56). During operating conditions, the oil from the delivery passage (31) is passed through the primary valve (51) and the pressure also acts directly on the secondary valve (52). This condition is called floating of primary valve (51) in the hydraulic dual valve assembly (50). Thus, the secondary valve (52) moves against the secondary spring member (54) to open the second inlet port (56). Therefore, some quantity of oil from the delivery passage (31) returns back to the inlet passage (30) through the second return passage (33) which results in the drop in the outlet pressure and the quantity of oil delivered to the engine lubrication circuits (101) is also reduced. This is shown by line EF in FIG. 8 .Thus at high speeds conditions, only required amount of oil is delivered and reduces the excess supply of oil to the engine. Thus the power consumption of the system gets reduced and engine fuel efficiency is improved. FIG.7 is a schematic layout of fifth operational mode of the VPOP system (100) during shutoff limit. According to an embodiment of the present invention, when the speed of the inner rotor (20) exceeds the predetermined speed N5, that is, very high speed or shutoff limit, and the pressure developed in the delivery passage (31) reaches shutoff limit, the secondary valve (52) moves in the direction Al which opens the shutoff port (57). Thus excess quantity of oil from the delivery passage (31) returns back to the oil sump (102) through the relief passage (34) and through the second return passage (33) to the inlet passage (30). Thus, the outlet pressure is dropped immediately to safeguard against the delivery pressure and the quantity of oil delivered to the engine lubrication circuits (101) is also reduced. This is shown by line FG in FIG. 8. Thus the VPOP system (100) also provides safety against shutoff pressure.

Various modifications to these embodiments are apparent to those skilled in the art from the description and drawings herein. The principles associated with the various embodiment defined herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be provided broadest scope consistent with the principles and novel and inventive features describe/disclosed or suggested herein. Any modifications, equivalent substitutions, improvements etc. within the spirit and principle of the present invention shall all be included in the scope of protection of the present invention.

Claims

We claim:

1. A Variable Pressure Oil Pump (VPOP) system (100) for internal combustion engine comprising:

an inlet passage (30) fluidically connected to an oil sump (102); a delivery passage (31) fluidically connected to the engine lubrication circuits

(101);

a hydraulic dual valve assembly (50) operating at predetermined engine speed conditions;

a first return passage (32) connected to the inlet passage (30) through the hydraulic dual valve assembly (50);

a second return passage (33) connected to the inlet passage (30) ; and a relief passage (34) in the hydraulic dual valve assembly (50) for relieving the pressure developed in the delivery passage (31);

wherein,

the said hydraulic dual valve assembly includes:

a primary valve (51) resting on a primary spring member (53);

a secondary valve (52) resting on a secondary spring member (54); a first inlet port (55) for providing inlet to the first return passage (32); a second inlet port (56) for providing inlet to the second return passage

(33);

a shutoff port (57) for providing inlet to the relief passage (34);

a port (58) connecting the first return passage (32) to the inlet passage (30); and

a port (59) connecting the second return passage (33) to the inlet passage (30).

2. The VPOP system (100) as claimed in claim 1, wherein the primary spring member (53) connects the primary valve (51) and the secondary valve (52).

3. The VPOP system (100) as claimed in claim 2, wherein the primary valve (51) floats inside the hydraulic dual valve assembly (50).

4. The pumping system as claimed in claim 1, wherein the hydraulic dual value assembly

(50) regulates the flow of oil from the inlet passage (30) to the delivery passage (31) at medium and high speed conditions.

5. The VPOP system (100) as claimed in claim 1, wherein the hydraulic dual valve assembly (50) allows some quantity of oil to return from the delivery passage (31) to the inlet passage (30) through the first return passage (32) at transition from lower speed to first range of medium speed conditions.

6. The VPOP system (100) as claimed in claim 1, wherein the hydraulic dual valve assembly (50) allows more quantity of oil to return from the delivery passage (31) to the inlet passage (30) through the first return passage (32) at first range of medium speed conditions.

7. The VPOP system (100) as claimed in claim 1, wherein the hydraulic dual valve assembly (50) closes the port (58) and disconnects the first return passage (32) to the inlet passage (30) at second range of medium speed conditions.

8. The VPOP system (100) as claimed in claim 1, wherein the hydraulic dual valve assembly (50) opens the second inlet port (56) to allow some quantity of oil to return back from the delivery passage (31) to the inlet passage (30) through the second return passage (33) at high speed conditions.

9. The VPOP system (100) as claimed in claim 1, wherein the hydraulic dual valve assembly (50) opens the shutoff port (57) to return excess quantity of oil to the oil sump (102) through the relief passage (34) and through the second return passage (33) to inlet passage (30) at shutoff limit and/or very high speed conditions.

10. The VPOP system (100) as claimed in claim 1, wherein the secondary spring member (54) is connected to a retainer member (60) fitted at the bottom of the hydraulic dual valve assembly (50).