FIELD OF THE INVENTION

The present invention generally relates to a variable delivery oil pump (VDOP) and more particularly, to a system for effective control of variable delivery oil pump (VDOP) which varies the oil quantity delivered to the engine according to specific engine operating conditions and speeds.

BACKGROUND

A lubrication unit such as an oil pump in engines and related systems are used for pressurizing the working fluid such as oil and delivering the fluid to lubrication circuits. Conventional oil pumps, for example, gerotor type oil pumps are used to deliver oil quantity linearly proportional to engine speeds. However, at higher engine speeds, such pumps deliver excess amount of oil and leads to an engine power loss. Thus, in order to overcome the above drawbacks, the variable delivery oil pumps were developed, which were configured to deliver the required quantity of oil according to engine requirements both at low and high speeds.

As known, a variable delivery oil pump consists of a main pump area having internal cavities for oil flow, a sliding ring placed inside the cavity and a rotor seated inside the sliding ring. In a typical variable delivery oil pump, the rotor has radial slots, where plurality of vanes are aligned inside the slots, such that when the engine runs at high speeds and the pressure of the system increases, the sliding ring moves from its position to predetermined position, also called as minimum eccentricity position, against the spring biasing force to reduce the eccentricity of the pump. As a result, the output quantity of oil delivery is reduced and required quantity is maintained. Similarly, when the engine runs at lower speeds and the pressure in the system decreases, the sliding ring moves towards the maximum eccentric position by means of spring force and consequently more quantity of oil delivery is achieved. The movement of sliding ring determines the output volume of the pump and hence determines the quantity of oil delivered to the engine. However, such an oil delivery system does not provide an effective control on the movement of the sliding ring when the pressure inside the system fluctuates suddenly and also if there is an electronic failure, the whole pumps system fails to do its intended function. Thus, the present invention aims to make the effective control of the variable delivery oil pump and also to run the pump system continuously even if the electronic failure occurs. The electronic control setup used in the present invention need not to be operated on all conditions which reduces the power consumption of the VDOP system. The present invention has been devised to mitigate the above mentioned drawbacks.

OBJECT OF THE INVENTION

It is the principal object of the present invention to provide a system and a method to effectively control oil quantity delivered to the engine for specific engine operating condition and speeds.

It is another object of the present invention to reduce power consumption of the pump system and to save power loss in the engine, while delivering excess quantity of oil to the engine.

SUMMARY OF THE INVENTION

The present invention discloses a system to address the above mentioned problems and to effectively control oil quantity delivered to engine for specific operating condition and speeds.

According to an embodiment of the present invention, a Variable Delivery Oil Pump (VDOP) system comprising a pumping unit and an internal cavity for oil flow, a sliding ring, at least one rotor housed inside the sliding ring, at least one hydraulically controlled dual valve assembly for regulating and relieving the pressure developed in the delivery line, a first return conduit connected to the hydraulic dual valve assembly for returning the oil back to an inlet side through a conduit and a second return conduit for returning the oil back to the inlet side, a relief conduit for reliving the pressure developed in a delivery conduit during shutoff conditions and an electronic control setup actuated by an electronic control unit at predetermined operating conditions for reducing the pressure in a spring chamber.

According to an embodiment of the present invention, the hydraulic dual valve assembly further comprises a primary valve and a secondary valve.

According to an embodiment of the present invention, the primary valve floats with respect to the secondary valve member. According to an embodiment of the present invention, the electronic control setup directly drains the oil from the spring chamber to reduce the pressure inside the spring chamber at predetermined operating conditions.

According to an embodiment of the present invention, the hydraulic dual valve assembly has four modes of operation.

According to an embodiment of the present invention, the hydraulic dual valve assembly during the first mode of operation regulates the oil going inside the spring chamber.

According to an embodiment of the present invention, the hydraulic dual valve assembly during the second mode of operation returns the oil back to the inlet side through the first return conduit and the conduit.

According to an embodiment of the present invention, the hydraulic dual valve assembly during the third mode of operation returns the oil back to the inlet side through the second return conduit .

According to an embodiment of the present invention, the hydraulic dual valve assembly during the fourth mode of operation returns the oil directly to the sump through the relief conduit.

According to an embodiment of the present invention, the oil is drained from the spring chamber through the first return conduit on failure of the electronic control setup.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a front view of a pumping unit of a variable delivery oil pump (VDOP) system in accordance with an embodiment of the present invention, in which the slider ring is at maximum eccentricity position.

Figure 2 illustrates schematic layout configuration of a pumping unit according to an embodiment of the present invention.

Figure 3 illustrates first mode of operation of a hydraulic dual valve assembly according to an embodiment of the present invention. Figure 4 illustrates schematic layout configuration of the VDOP system when electronic control setup is activated according to an embodiment of the present invention.

Figure 5 illustrates second mode of operation of the VDOP system according to an embodiment of the present invention.

Figure 6 illustrates third mode of operation of the VDOP system according to an embodiment of the present invention.

Figure 7 illustrates fourth mode of operation of the VDOP system according to an embodiment of the 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 complete specification.

Figure 1 illustrates a front view of a pumping unit of a variable delivery oil pump (VDOP) system in accordance with an embodiment of the present invention. The pumping unit (20) includes a housing (21) having an internal cavity (22) for fluid flow. The pumping unit (20) is mounted on an engine (not shown) with a suitable gasket and the pumping unit (20) supplies pressurized working fluid to the engine. The pumping unit (20) also includes a sliding ring

(23) which is located on the pump area and moves according to the engine demand. A rotor

(24) having radial slots (24a) are arranged inside the sliding ring (23) and each radial slot (24a) accommodates a vane (25) of suitable size. The outer faces of the vane (25) are engaged with the inner surface (30) of the sliding ring (23) and slides radially in the radial slot (24a) when the rotor (24) rotates around its central axis. A cam ring (26) is aligned on top of the rotor (24) where the inside faces of the vanes (25) rest. When the pump is driven by the drive member, the rotor (24) rotates and the vanes (25) in the rotor (24) move radially outwards. Two successive vanes (25) and the inner surface (30) of the sliding ring (23) forms a working volume which when multiplied with number of the vanes (25) gives the total delivery volume of the pump during one revolution. The volume of working fluid such as oil changes as pump rotates, in which, the working volumes become smaller when the vanes (25) are approaching at a delivery side (29) and the working volume becomes larger when the vanes (25) are approaching at the inlet side (28). This change of volume creates pump action allowing fluid to be sucked from the inlet side (28) and delivers the working fluid through delivery side (29).

A main pressure chamber (33) is formed in the housing (21) at one end of the sliding ring (23) and a spring chamber (34) is formed at other end of the sliding ring (23). A spring member (27) is accommodated in the spring chamber (34) which produces returning force on the sliding ring (23) to return back to maximum eccentricity position. The pressure difference between the main pressure chamber (33) and the spring chamber (34) creates a driving force on the sliding ring (23), which moves to vary the eccentricity of the VDOP . The oil is delivered to an engine related systems (100) through a delivery line (80) and after lubrication, oil is drained to a sump (102) through a conduit (87).

Figure 2 illustrates schematic layout configuration of a pumping unit (20) according to an embodiment of the present invention. The pumping unit (20) is shown therein having a hydraulic dual valve assembly (50) and an electronic control setup (51) incorporated in the pumping unit (20). When the pump is driven by the drive member, oil is sucked from the sump (102) through an inlet conduit (31) and delivers the oil to the engine through a delivery conduit (32). A portion of oil delivered to the engine (100) is diverted through a conduit (81) to the main pressure chamber (33). Another portion of the oil is diverted through a conduit (82) to the hydraulic dual valve assembly (50), which will be described below.

The hydraulic dual valve assembly (50) has a primary valve (53) seated against a primary spring member (55). The delivery conduit (32) is connected to the hydraulic dual valve assembly (50) through the conduit (82) and a port (63). When delivery pressure (pi) reaches first controlled pressure (PI*), the primary valve (53) moves against the primary spring member (55) force and opens the port (57) made in the cylinder (52). The primary valve (53) is seated on a secondary valve (54) through the primary spring member (55). One end of a secondary spring member (56) is connected to the secondary valve (54) and the other end of the secondary spring member (56) is seated on a retainer member (64) which is placed at one end of the hydraulic dual valve assembly (50). The secondary valve (54) opens the port (58) in the cylinder (52) when the pressure in the delivery line (80) reaches a second control pressure (P2*) and opens a port (59) in the cylinder (52) when the pressure (Pl) in the delivery line (80) attains high pressure (P3*). A port (60) is opened when the delivery line (80) pressure (Pl) attains shutoff pressure (P4*).The primary valve (53) and secondary valve (54) can be of any other shape than the ones shown in the figures.

The VDOP system along with the inlet conduit (31) and the delivery conduit (32) further comprises a first return conduit (88) which returns the oil back to the inlet side (28) through a conduit (89) during medium pressure conditions and also during electronic control setup (51) failure conditions. The electronic control setup (51) drains the oil through a conduit (86). A second return conduit (84) is provided for returning the oil back to the inlet side (28) at high pressure conditions and a relief conduit (85) is provided for relieving the oil pressure during shutoff conditions.

The hydraulic dual valve assembly (50) comprises a first port (57), which directs the fluid entering from conduit (82) to the spring chamber (34) through a conduit (83) and has a second port (58), which directs the oil entering from the conduit (82) to the inlet side (28) through the first return conduit (88). The ports (58, 61, 62) are connected to create the first return conduit (88) which returns the oil back to the inlet side (28) through the conduit (89). The hydraulic dual valve assembly (50) further includes a third port (59) that connects the conduit (82) to the inlet side (28) through the conduit (84) and a shutoff port (60) that relieves the pressure in the delivery line (80) when the pressure exceeds the shutoff pressure. The electronic control setup (51), incorporated in the pumping unit (20), drains the oil from the spring chamber (34) to the sump (102) when actuated by the electronic control unit (101).

Figures 3-7 illustrate different modes of operation of the VDOP system according to an embodiment of present invention. During the initial running conditions, the oil flows to the main pressure chamber (33) through the conduit (81) so that the main pressure chamber (33) maintains delivery line pressure (Pl). The sliding ring (23) at this condition maintains the maximum eccentricity position because of the spring member (27) accommodated in the spring chamber (34). When the pressure (Pl) in the delivery line (80) reaches the first control pressure (Pl*), the primary valve (53) moves from its initial position against the primary spring member (55) and opens the port (57). Thus, a portion of working fluid flows from the delivery side (29) to the spring chamber (34) through the conduit (83), resulting in pressure increase in the spring chamber (34). With this condition, the slider ring (23) is at maximum eccentricity condition. This will continue for the predetermined intermediate pressure (Pi*) which is illustrated in Figure 3.

Figure 4 illustrates schematic layout configuration of the VDOP system when electronic control setup (51) is activated according to an embodiment of the present invention. The working of the hydraulic dual valve assembly (50) in minimum eccentricity position of the sliding ring (23) is shown therein. When the engine (100) runs at higher speeds such as when the pressure (Pl) in the delivery line (80) increases above the predetermined intermediate pressure (Pi*), the electronic control unit (101) sends a signal to the electronic control setup (51) and actuates the electronic control setup (51). The electronic control setup (51) drains the fluid from the spring chamber (34) through the conduit (86) to the sump (102) and hence the pressure in the spring chamber (34) will be lower than the pressure in the main pressure chamber (33). This pressure difference creates a driving force for the sliding ring (23) to move from its initial position to the minimum eccentricity position. Thus the working volume of the pump is reduced and the quantity of fluid is controlled according to engine demand.

Figure 5 illustrates the second mode of operation of the VDOP system when the pumping unit (20) reaches the second controlled pressure (P2*) according to an embodiment of the present invention. When the pressure in the delivery line (80) reaches the second controlled pressure (P2*), the secondary valve (54) begins to move against the secondary spring member (56) and the port (58) begins to open. Thus, a portion of fluid diverted from the delivery side (29) is fed back to the inlet side (28) through the first return conduit (88) to relieve the pressure in the delivery line (80). Thus, the secondary valve (54) acts like a pressure relief valve of the VDOP system. During this mode of operation, electronic control setup (51) is not required to be actuated due to the pressure difference, oil from the spring chamber (34) can be drained to inlet side (28) through the first return conduit (88) and the conduit (89) without actuation of electronic control setup (51). Due to this pressure difference, the sliding ring (23) moves towards the minimum eccentricity position. Hence, even if the electronic failure occurs, the oil from the spring chamber (34) drains to the inlet side (28) through the first return conduit (88). Thus, the VDOP works continuously doing its intended function even after the electronic failure. Figure 6 illustrates the third mode of working of the VDOP system, wherein when the pressure in the delivery line (80) reaches the high pressure (P3*), the secondary valve (54) of the hydraulic dual valve assembly (50) begins to move against the secondary spring member (56) to open the port (59) in the cylinder (52). Thus, a portion of fluid diverted from the delivery side (29) is fed back to the inlet side (28) through the second return conduit (84) to relieve the pressure in the delivery line (80). During this operational mode, the secondary valve (54) closes the port (61) to block the first return conduit (88). Thus, the secondary valve (54) acts like a pressure relief valve of the VDOP system.

Figure 7 illustrates the fourth mode of operation of the VDOP system when the pumping unit (20) reaches the shutoff pressure (P4*) according to an embodiment of the present invention. When the pressure (Pl) in the delivery line (80) of the pumping unit (20) reaches the shutoff pressure (P4*), the secondary valve (54) moves further against the secondary spring member (56) to open the port (60). Thus, the fluid flows from the port (60) to the sump (102) through the conduit (85). Hence the secondary valve (54) also acts like a shutoff valve in the VDOP system.

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.