System for supplying hydraulic fluid to a hydraulic control in a transmission of a motor vehicle

Abstract

A system (10) for supplying hydraulic pressurized fluid (22) to a hydraulic control (38) in a transmission of a motor vehicle, the system (10) comprising: a pump (12) for supplying the hydraulic pressure fluid (22); a control device (37) for selectively transmitting the hydraulic pressure fluid (22) to the hydraulic control (38); a first one-way device (34) configured to communicate a hydraulic pressure fluid flow (22) from the pump (12) and prevent a hydraulic pressure fluid flow (22) to the pump (12); a bypass valve arrangement (40, 40') having an inlet port (40a) in communication with the first one-way device (34) and an outlet port (40b), the bypass valve arrangement (40, 40') having an element (46, 46') movable between at least a first position and a second position, the inlet port (40a) of the bypass valve arrangement (40, 40') not communicating with the outlet port (40b) of the bypass valve arrangement (40, 40') when the element (46, 46') is in the first position, and the inlet port (40a) of the bypass valve arrangement (40, 40') communicating with the outlet port (40b) of the bypass valve arrangement (40, 40') when the element (46, 46') is in the second position, and wherein the element (46, 46') is biased into the first position by a force acting on the element (46, 46') due to a biasing element (62); a pressure accumulator (70) in communication with the outlet port (40b) of the bypass valve arrangement (40, 40'); a second one-way device (41) configured to transmit a hydraulic pressure fluid flow (22) from the accumulator (70) and prevent a hydraulic pressure fluid flow (22) to the accumulator (70); wherein the pressure accumulator (70) is filled when the control device (37) is closed and the element (46, 46') is moved from the first position to the second position, when a force acting on the element (46, 46') due to the hydraulic pressure fluid (22) at the inlet port (40a) of the bypass valve arrangement (40, 40') exceeds the force acting on the element (46, 46') due to the biasing element (62); characterized in that the control device (37) is located downstream of both the first one-way device (34) and the second one-way device (41), thereby enabling only the pressure accumulator (70) and not the hydraulic control (38) to be supplied with hydraulic pressure fluid (22) when the control device (37) is closed.

Description

AREA

[0001] The invention relates to a system for supplying hydraulic fluid to a hydraulic control in a transmission of a motor vehicle according to the preamble of claim 1, as known from DE 41 30 128 A1. BACKGROUND

[0002] A typical automatic transmission includes a hydraulic control system used, among other functions, to operate multiple torque-transmitting devices. These torque-transmitting devices may be, for example, friction clutches and brakes. The conventional hydraulic control system typically includes a main pump that supplies pressurized fluid, such as oil, to multiple valves and solenoid valves within a valve body. The main pump is driven by the engine or electric motor of the motor vehicle. The valves and solenoid valves are operable to direct the pressurized hydraulic fluid through a hydraulic fluid circuit to the multiple torque-transmitting devices in the transmission. The pressurized hydraulic fluid delivered to the torque-transmitting devices is used to engage or disengage the devices to achieve different gear ratios.

[0003] In certain transmission designs, actuation of the torque-transmitting devices is achieved by selectively releasing an accumulator filled with hydraulic fluid. The accumulator is intermittently filled by the main pump, and the main pump is typically disabled when it is not filling the accumulator. However, during vehicle startup, when the accumulator is empty, there is a delay in the operation of the hydraulic control system as the pump first fills the accumulator before the accumulator can supply pressurized hydraulic fluid to the hydraulic control system. Therefore, there is scope in the art for a system to reduce or eliminate the shift delay time due to accumulator filling during vehicle startup. SUMMARY

[0004] The invention relates to a system with the features of claim 1 for providing hydraulic pressurized fluid in a transmission of a motor vehicle. The system comprises a pump for supplying hydraulic pressurized fluid, which pump has an inlet port and an outlet port. A bypass valve arrangement comprises an inlet port in communication with the pump's outlet port and an outlet port in communication with a pressure accumulator. The pump and the pressure accumulator are both connected to a hydraulic control system that controls, lubricates, and cools the transmission of the motor vehicle.The bypass valve assembly includes a valve movable between at least a first position and a second position, wherein the inlet port of the bypass valve assembly is not in communication with the outlet port of the bypass valve assembly when the valve is in the first position, and the inlet port of the bypass valve assembly is in communication with the outlet port of the bypass valve assembly when the valve is in the second position. The bypass valve assembly is in the first position when the vehicle is first started, so that the pump bypasses filling the accumulator and instead fills the hydraulic control system. The valve moves to the second position once the hydraulic control system is filled or saturated, and the pump then fills the accumulator. The accumulator supplies pressurized hydraulic fluid to the hydraulic control system.The pump fills the pressure accumulator as needed during transmission operation.

[0005] In one example of a system, the system includes one-way ball check valves to prevent backflow to the pump when the pump is deactivated and to prevent flow to the accumulator until the control system is filled.

[0006] In another example of the system, the valve includes ports and channels that communicate with the inlet port and the outlet port of the bypass valve assembly.

[0007] In yet another example of the system, the bypass valve assembly includes seals that seal against the valve when the valve is in the first position, thereby interrupting communication between the inlet port and the outlet port.

[0008] Further areas of applicability will become apparent from the description provided herein. It is to be understood that the description and specific examples are for illustrative purposes only. DRAWINGS

[0009] The drawings described herein are for illustrative purposes only. Fig. 1 is a schematic diagram of a subsystem of a hydraulic control system operable to provide pressurized hydraulic fluid flow to the hydraulic control system in accordance with the principles of the present invention; Fig. 1A is an enlarged view of a portion of the subsystem of Fig. 1 in a first operating mode; Fig. Figure 1B is an enlarged view of the section of the subsystem of Fig. 1 and Fig. 1A in a second operating mode; and Fig. 2 is a schematic diagram of another example of a subsystem of a hydraulic control system operable to provide pressurized hydraulic fluid flow to the hydraulic control system in accordance with the principles of the present invention. DETAILED DESCRIPTION

[0010] The following description is merely exemplary.

[0011] Now with reference to Fig. 1, a subsystem of a hydraulic control system for a transmission of a motor vehicle is indicated generally by reference numeral 10. The subsystem 10 operates as a source of pressurized hydraulic fluid for the hydraulic control system and includes a pump 12 in fluid communication with a sump 14. The pump 12 may be driven directly by an engine in the motor vehicle or by an electric motor or other prime mover. The pump 12 includes an inlet port 16 and an outlet port 18. The inlet port 16 communicates with the sump 14, and the outlet port 18 communicates with a filter 20. The pump 12 may be of various types, for example, a gear pump, a vane pump, an internal gear pump, or any other positive displacement pump. The sump 14 is a fluid reservoir, typically located at the bottom of the hybrid transmission, and operable to store a hydraulic fluid 22.The sump 14 includes an outlet port 24. The hydraulic fluid 22 is forced from the sump 14 by the pump 12 and communicated from the outlet port 24 of the sump 14 to an inlet port 16 of the pump 12 via a suction line 26. The outlet port 18 of the pump 12 communicates a flow of pressurized hydraulic fluid 22 to an intermediate line 30. The intermediate line 30 communicates with the filter 20.

[0012] The filter 20 filters the flow of hydraulic fluid 22 and communicates with a second intermediate line 32. The second intermediate line 32 communicates with a one-way ball check valve 34. The check valve 34 communicates with a main supply line 36. The check valve 34 allows fluid communication in only one direction. For example, the check valve 34 allows fluid communication from the second intermediate line 32 to the main supply line 36 and prevents fluid communication from the main supply line 36 to the second intermediate line 32.

[0013] The main supply line 36 communicates with a control device 37, which communicates with the various other subsystems of the hydraulic control system, indicated by reference numeral 38. The various other subsystems of the hydraulic control system 38 may include, for example, torque transfer device control subsystems, lubrication control subsystems, compensator subsystems, torque converter control subsystems, cooling subsystems, etc. The control device 37 controls the flow of hydraulic fluid to the hydraulic control system 38. The control device 37 may be, for example, an on / off solenoid valve. The main supply line 36 also communicates with a bypass valve assembly 40 and a second one-way ball check valve 41.

[0014] The bypass valve assembly 40 is operable to allow selective fluid communication between the main supply line 36 and an accumulator feed line 42. Fig. 1A and Fig. 1B, the bypass valve assembly 40 includes an inlet port 40A, an outlet port 40B, and a drain port 40C. The inlet port 40A is in fluid communication with the main supply line 36. The outlet port 40B is in fluid communication with the accumulator feed line 42. The drain port 40C is in fluid communication with a drain line 44 that communicates with the sump 14.

[0015] The bypass valve assembly 40 further includes a valve or piston 46 slidably disposed within a bore 48. The valve 46 is sealed to the bore 48 by at least one annular seal 50. The valve 46 includes a first valve land 49. The first valve land 49 preferably has a cylindrical shape and is sized to fit within the bore 48. The valve 46 includes at least one side port 52 in the first valve land 49 that communicates with a transverse fluid channel 54 disposed perpendicular to the axis of the valve 46. The transverse fluid channel 54 communicates with an axial fluid channel 56 that communicates with an end port 58. The end port 58 is located at a distal end 60 of the valve 46. The end port 58 communicates with the inlet port 40A of the bypass valve assembly 40.

[0016] The valve 46 is movable between at least two positions. In a first position or retracted position, which is Fig. 1A, the outlet port 40B is closed by the valve 46. In a second or extended position shown in Fig. 1B, the outlet port 40B is in fluid communication with the side port 52 of the valve 46. The valve 46 is biased to the retracted position by a biasing member 62. The biasing member 62 is supported by a support post 53 coupled to a second valve land 55 attached to one end of the first valve land 49. The biasing member 62 acts on a second distal end 64 of the valve 46 opposite the distal end 60. The valve 46 is moved to the extended position by hydraulic fluid 22 acting on the end 60 of the valve 46 against the bias of the biasing member 62, as described below. The bypass valve assembly 40 is set to a minimum hydraulic fluid system pressure.

[0017] Returned to Fig. 1, the second one-way ball check valve 41 communicates with the accumulator supply line 42. The check valve 41 allows fluid communication in only one direction. For example, the check valve 41 allows fluid communication from the accumulator supply line 42 to the main supply line 36 and prevents fluid communication from the main supply line 36 to the accumulator supply line 42.

[0018] The accumulator supply line 42 communicates with an accumulator 70 and a pressure sensor 72. The accumulator 70 is an energy storage device in which the incompressible hydraulic fluid 22 is maintained under pressure by an external source. In the example cited, the accumulator 70 is a spring-type or gas-filled accumulator comprising a spring or a compressible gas that exerts a compressive force on the hydraulic fluid 22 in the accumulator 70. However, it should be noted that the accumulator 70 may be of other types without departing from the scope of the present invention. Accordingly, the accumulator 70 is operable to supply pressurized hydraulic fluid 22 to the main supply line 36 through the second check valve 41. However, when the accumulator 70 is emptied, the check valve 34 prevents the pressurized hydraulic fluid 22 from returning to the pump 12.When filled, the accumulator 70 effectively replaces the pump 12 as the source of pressurized hydraulic fluid 22, eliminating the need for the pump 12 to run continuously. The main pressure sensor 72 reads the pressure of the hydraulic fluid 22 in the accumulator supply line 42 in real time and provides this data to a transmission control module (not shown).

[0019] The components of hydraulic control subsystem 10 are connected via a plurality of fluid communication lines, as described above. It should be appreciated that the fluid communication lines may be integrated into a valve body or formed from separate tubes or pipes without departing from the scope of the present invention. Additionally, the fluid communication lines may have any cross-sectional shape and may include additional or fewer bends, turns, and branches than illustrated.

[0020] With combined reference to the Fig. 1, Fig. 1A, Fig. 1B and Fig. 2, the operation of the hydraulic control subsystem 10 will now be described. The pump 12 is primarily used to fill the accumulator 70. The actuation of torque-transmitting devices, lubrication, and cooling in the hydraulic control system 38 is achieved via draining the accumulator 70. Opening the control device 37 allows the pump 12 and the accumulator 70 to deliver a flow of pressurized hydraulic fluid 22 to the hydraulic control system 38. Closing the control device 37 allows the pump 12 to fill the accumulator 70. The subsystem 10 operates to fill the accumulator 70 using the pump 12 and to reduce the amount of loss due to the pump 12 continuously operating by allowing the pump 12 to be deactivated while the accumulator 70 delivers a flow of pressurized hydraulic fluid 22 to the hydraulic control system 38.

[0021] During a start-up condition where the main supply line 36, the hydraulic control system 38, and the accumulator 70 are not pressurized with hydraulic fluid 22, the pump 12 is commanded to operate, and a flow of pressurized hydraulic fluid 22 is drawn from the sump 14, through the pump 12, through the filter and check valve 34 to the main supply line 36. Initially, the pressure of the hydraulic fluid 22 in the main supply line 36 is insufficient to overcome the bias of the biasing element 62 of the bypass valve assembly 40. Accordingly, the valve 46 remains retracted, thereby isolating the accumulator 70 from the main supply line 36.Therefore, the flow of pressurized hydraulic fluid 22 from pump 12 is directed directly to hydraulic control system 38, providing system pressure to hydraulic control system 38 and allowing hydraulic control system 38 to operate efficiently immediately after vehicle start-up. As hydraulic control system 38 becomes saturated, the pressure in main supply line 36 increases. The increasing pressure in main supply line 36 creates a force on distal end 60 of valve 46, and valve 46 extends against biasing member 62 to the extended position. Accordingly, hydraulic fluid 22 communicates through accumulator supply line 42 and fills accumulator 70.

[0022] During normal operating conditions, the main pressure sensor 72 is used to monitor the pressure of the hydraulic fluid 22 in the accumulator 70. If the accumulator 70 is not fully filled or drops below a threshold, the transmission control module commands the pump 12 to operate. Closing the solenoid valve 37 prevents the flow of hydraulic fluid to the hydraulic control system 38, but allows the pump 12 to fill the accumulator 70. A flow of pressurized hydraulic fluid 22 passes through the check valve 34 to the main supply line 36, through the bypass valve assembly 40 and the accumulator feed line 42 to the accumulator 70.Once the main pressure sensor 72 detects a pressure of the hydraulic fluid 22 in the accumulator 70 indicating that the accumulator 70 is completely full, the transmission control module instructs the pump 12 to cease operation, and the accumulator 70 is emptied as necessary to deliver pressurized hydraulic fluid 22 through the check valve 41 to the main supply line 36. Alternatively, the pump 12 may remain in operation and deliver a flow of pressurized hydraulic fluid 22 to the main supply line 36 in conjunction with the emptying of the accumulator 70. Control of the accumulator 70 may be accomplished using a control device, such as an on / off solenoid valve, located downstream of the accumulator in the hydraulic control system 38.

[0023] Fig.Turning to Figure 2, an alternative bypass valve assembly is indicated generally by reference numeral 40'. The bypass valve assembly 40' is similar to the bypass valve assembly 40 described above, and therefore like components are indicated by like reference numerals. However, the bypass valve assembly 40' includes a valve 46'. The valve 46' is similar to the previously described valve 46, however, the valve 46' does not include any ports or passages. Instead, the bypass valve assembly 40' includes an annular seal 47 that operates to seal the inlet port 40A from the outlet port 40B when the valve 46' is retracted. The annular seal 47 is disposed around the inlet port 40A such that the biasing force of the biasing member 62 seals a distal end 60' of the valve 46' to the seal 47, thereby sealing the inlet port 40A from the outlet port 40B. The bypass valve assembly 40' also includes a plurality of guides 50.The bypass valve assembly 40' operates in a similar manner to the bypass valve assembly 40 described above.

[0024] Subsystem 10 of the present invention reduces the feed time of hydraulic control system 38 when accumulator 70 is drained, minimizes accumulator pre-charge losses, and can be designed to function as a reserve spring accumulator. The net result is a reduction in the shift time delay associated with initial shifts after vehicle start-up.

Claims

[1] A system (10) for supplying hydraulic pressurized fluid (22) to a hydraulic control (38) in a transmission of a motor vehicle, the system (10) comprising: a pump (12) for supplying the hydraulic pressure fluid (22); a control device (37) for selectively transmitting the hydraulic pressure fluid (22) to the hydraulic control (38); a first one-way device (34) configured to communicate a hydraulic pressure fluid flow (22) from the pump (12) and prevent a hydraulic pressure fluid flow (22) to the pump (12); a bypass valve arrangement (40, 40') having an inlet port (40a) in communication with the first one-way device (34) and an outlet port (40b), the bypass valve arrangement (40, 40') having an element (46, 46') movable between at least a first position and a second position, the inlet port (40a) of the bypass valve arrangement (40, 40') not communicating with the outlet port (40b) of the bypass valve arrangement (40, 40') when the element (46, 46') is in the first position, and the inlet port (40a) of the bypass valve arrangement (40, 40') communicating with the outlet port (40b) of the bypass valve arrangement (40, 40') when the element (46, 46') is in the second position, and wherein the element (46, 46') is biased into the first position by a force acting on the element (46, 46') due to a biasing element (62); a pressure accumulator (70) in communication with the outlet port (40b) of the bypass valve arrangement (40, 40'); a second one-way device (41) configured to transmit a hydraulic pressure fluid flow (22) from the accumulator (70) and prevent a hydraulic pressure fluid flow (22) to the accumulator (70); wherein the pressure accumulator (70) is filled when the control device (37) is closed and the element (46, 46') is moved from the first position to the second position, when a force acting on the element (46, 46') due to the hydraulic pressure fluid (22) at the inlet port (40a) of the bypass valve arrangement (40, 40') exceeds the force acting on the element (46, 46') due to the biasing element (62); characterized by , that the control device (37) is located downstream of both the first one-way device (34) and the second one-way device (41), thereby enabling only the pressure accumulator (70) and not the hydraulic control (38) to be supplied with hydraulic pressure fluid (22) when the control device (37) is closed. [2] The system of claim 1, wherein the element (46) is a valve slidably disposed within and sealed to a bore (48), the valve having a first port (58) in communication with the inlet port (40a) and a second port (52) in communication with the first port (58), the second port (52) communicating with the outlet port (40b) when the valve (46) is in the second position and not communicating with the outlet port (40b) when the valve (46) is in the first position. [3] The system of claim 2, wherein the first port (58) and the second port (52) communicate via a fluid communication channel (54, 56) in the valve (46). [4] The system of claim 3, wherein the second port (57) is oriented at ninety degrees with respect to the first port (58). [5] The system of claim 2, wherein the biasing member (67) acts on an end of the valve (46) opposite an end of the valve (46) to which the pressurized hydraulic fluid (22) acts at the inlet port (40a). [6] The system of claim 1, wherein the member (46) is a piston slidably disposed within and sealed to a bore (48), the piston having a first end (64) and a second end (60), the first end (64) in contact with the biasing member (62) and the second end (60) in communication with the inlet port (40a). [7] The system of claim 6, wherein the bypass valve assembly (40') further comprises an annular seal (47) disposed around the inlet port (40a), and the second end (60) of the piston is sealed to the annular seal (47) when the piston is in the first position. [8] System according to claim 1, wherein the control device (37) is an electrically activated solenoid valve (37). [9] The system of claim 1, wherein the first and second one-way devices (34, 41) are ball check valves. [10] The system of claim 1, further comprising a pressure sensor (72) in communication with the accumulator (70), wherein the control device (37) is closed when the pressure of the hydraulic fluid (22) in the accumulator (70) is lower than a threshold pressure.

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