GB2322421A - Automatic transmission fluid level control - Google Patents

Automatic transmission fluid level control Download PDF

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Publication number
GB2322421A
GB2322421A GB9703462A GB9703462A GB2322421A GB 2322421 A GB2322421 A GB 2322421A GB 9703462 A GB9703462 A GB 9703462A GB 9703462 A GB9703462 A GB 9703462A GB 2322421 A GB2322421 A GB 2322421A
Authority
GB
United Kingdom
Prior art keywords
automatic transmission
hydraulic fluid
fluid
reservoir
input
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9703462A
Other versions
GB9703462D0 (en
GB2322421B (en
Inventor
Albert Bromhorst
Pascal Marques-Bras
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Delphi Automotive Systems France
Original Assignee
Delphi Automotive Systems France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Delphi Automotive Systems France filed Critical Delphi Automotive Systems France
Priority to GB9703462A priority Critical patent/GB2322421B/en
Publication of GB9703462D0 publication Critical patent/GB9703462D0/en
Publication of GB2322421A publication Critical patent/GB2322421A/en
Application granted granted Critical
Publication of GB2322421B publication Critical patent/GB2322421B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating
    • F16H57/0447—Control of lubricant levels, e.g. lubricant level control dependent on temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/0021—Generation or control of line pressure
    • F16H2061/0037—Generation or control of line pressure characterised by controlled fluid supply to lubrication circuits of the gearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating
    • F16H57/0434—Features relating to lubrication or cooling or heating relating to lubrication supply, e.g. pumps ; Pressure control
    • F16H57/0443—Features relating to lubrication or cooling or heating relating to lubrication supply, e.g. pumps ; Pressure control for supply of lubricant during tilt or high acceleration, e.g. problems related to the tilt or extreme acceleration of the transmission casing and the supply of lubricant under these conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating
    • F16H57/045—Lubricant storage reservoirs, e.g. reservoirs in addition to a gear sump for collecting lubricant in the upper part of a gear case
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/0021—Generation or control of line pressure

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Details Of Gearings (AREA)

Abstract

An automatic transmission (10) for a motor vehicle comprising a number of friction devices (12,12') operated by hydraulic fluid to provide a number of different gear ratios; a housing (14) having a main reservoir (16) for storing the hydraulic fluid; an end fitting (24) attached to one end of the housing; seal means (28) between the housing and the end fitting and defining with the end fitting an auxiliary reservoir (26) within the end fitting; input means (32,36) including a fluid passage through the seal means for transferring hydraulic fluid to the auxiliary reservoir at or below a predetermined gear ratio; and output means (34,38) including a fluid passage through the seal means for transferring any hydraulic fluid in the auxiliary reservoir from the auxiliary reservoir to the main reservoir at gear ratios above the predetermined gear ratio. Provides an arrangement for reducing the volume of hydraulic fluid in the main reservoir during lower gear ratios.

Description

AUTOMATIC TRANSMISSION Technical Field The present invention relates to an automatic transmission for a motor vehicle, and in particular to an arrangement for selectively storing hydraulic fluid within the automatic transmission.
Background of the Invention An automatic transmission typically uses hydraulic fluid to control the operation of friction devices (clutches and brakes) within the transmission. Selected operation of the friction devices determines the gear ratio in use. The hydraulic fluid is stored in a reservoir or oil pan located in or at the bottom of the housing of the transmission. During high gear ratio operation (for example, first gear - high vehicle acceleration, low vehicle speed, operation) of the transmission, a large volume of hydraulic fluid is required in the reservoir. However, during low gear ratio operation (low vehicle acceleration, high vehicle speed, operation) of the transmission, a lower volume of hydraulic fluid in the reservoir is required. During this latter operation, a large volume of hydraulic fluid in the reservoir can result in temperature rises in the hydraulic fluid (due to excessive movement of the fluid), and aerating or foaming of the hydraulic fluid. It also has been proposed to added an additional storage reservoir to the transmission which is connected with the main reservoir by a thermally controlled valve for cold start operation of the automatic transmission. Such an arrangement adds both cost and weight to the transmission.
Summarv of the Invention It is an object of the present invention to overcome the above mentioned disadvantages.
To this end, an automatic transmission in accordance with the present invention for a motor vehicle comprises a number of friction devices operated by hydraulic fluid to provide a number of different gear ratios; a housing having a main reservoir for storing the hydraulic fluid; an end fitting attached to one end of the housing; seal means between the housing and the end fitting and defining with the end fitting an auxiliary reservoir within the end fitting; input means including a fluid passage through the seal means for transferring hydraulic fluid to the auxiliary reservoir at or below a predetermined gear ratio; and output means including a fluid passage through the seal means for transferring any hydraulic fluid in the auxiliary reservoir from the auxiliary reservoir to the main reservoir at gear ratios above the predetermined gear ratio.
The present invention provides an arrangement which reduces the volume of hydraulic fluid in the main reservoir during low acceleration, high speed, operation of the motor vehicle; which increases the volume of hydraulic fluid in the main reservoir during subsequent deceleration of the motor vehicle; without the need for adding an additional storage reservoir.
The present invention makes use of the end fitting which closes one end of the housing to provide an auxiliary reservoir, seal means which substantially prevents leakage of hydraulic fluid from the automatic transmission and for isolating the main reservoir from the auxiliary reservoir, and means which control the flow of hydraulic fluid in to and out of the auxiliary reservoir to thereby control the volume of hydraulic fluid in the main reservoir.
Brief Description of the Drawings The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of an automatic transmission in accordance with the present invention; Figure 2 is a schematic representation of the flow of hydraulic fluid in the automatic transmission of Figure 1; Figure 3 is an end view of the seal means of the automatic transmission of Figure 1; Figure 4 is a cross-sectional view on the line IV-IV of Figure 3; Figure 5 is a cross-sectional view of the housing, end fitting and seal means of the automatic transmission of Figure 1; Figures 6A to 6F are schematic presentations of a motor vehicle having an automatic transmission in accordance with the present invention during various stages of operation of the motor vehicle; and Figure 7 is a view similar to Figure 2 showing variations in accordance with the present invention which may be made to the automatic transmission of Figure 1.
Description of the Preferred Embodiment Referring to Figure 1, the automatic transmission 10 in accordance with the present invention for a motor vehicle comprises a number of friction devices 12, 12' (such as clutches or brakes) operated by hydraulic fluid to control the operation of gear members (not shown) to provide a number of different gear ratios for the automatic transmission. A housing 14 surrounds the friction devices 12 and gear members and defines a main reservoir 16 for storing the hydraulic fluid. A pump 18 pumps hydraulic fluid to the friction devices 12, and the sequence of operation of the friction devices is controlled by, for example, solenoid valves 20 dependent on the required gear ratio. Such an arrangement is well known to those skilled in the art and will not be described in greater detail. The housing 14 has a rear end 22 which is directed towards the rear of the motor vehicle when the automatic transmission 10 is mounted in the motor vehicle. The rear end 22 is open but in use is closed by an end fitting 24. The end fitting 24 defines an auxiliary reservoir 26. Seal means 28 is positioned between the housing 14 and the end fitting 24 and forms a separation wall between the main reservoir 16 and the auxiliary reservoir 26. The hydraulic fluid line 30 to one of the friction devices 12' is fluidly connected by an input fluid line 32 passing through an input aperture 36 in the seal means 28 to the auxiliary reservoir 26 to allow the passage of hydraulic fluid to the auxiliary reservoir when that friction device 12' is operating. The auxiliary reservoir 26 is fluidly connected by an output fluid line 34 passing through an output aperture 38 in the seal means 28 to the main reservoir 16 to allow the passage of hydraulic fluid from the auxiliary reservoir to the main reservoir. The seal means 28 and the movement of hydraulic fluid are described in more detail below.
As shown in Figure 2, input fluid line 32 includes the input aperture 36 which is formed as a restriction orifice to calibrate the flow of hydraulic fluid from the line 30 to the auxiliary reservoir 26. Output fluid line 34 includes the output aperture 38 which is formed as a restriction orifice 38 to calibrate the flow of hydraulic fluid from the auxiliary reservoir 26 to the main reservoir 16. Orifice 38 is smaller than orifice 36 so that the auxiliary reservoir 26 fills with hydraulic fluid when fluid is supplied in line 30 to operate the friction device 12'. The auxiliary reservoir 26 is also connected to the main reservoir 16 by an overflow fluid line 40 connected to an overflow aperture 42 passing through the seal means 28. The combination of aperture 42 and orifice 38 is the same size as or larger than the orifice 36 to substantially prevent any increase in fluid pressure in the auxiliary reservoir 26. The output aperture 36 is located towards the bottom of the seal means 28 and the overflow aperture 42 is located towards the top of the seal means, when the seal means is mounted on the motor vehicle.
The preferred arrangement for the seal means 28 is shown in Figures 3 to 5 for an end fitting 24 having a tubular extension 25 through which a drive shaft (not shown) for the automatic transmission 10 passes.
The seal means 28 comprises a substantially rigid outer annular frame 44; a substantially rigid inner annular wall 46; an annular compressible seal 48 between the outer frame and the inner wall; and an inwardly directed lip seal 50 around the inner edge of the inner wall. The outer frame 44 and inner wall 46 are preferably formed from a metallic material (such as aluminium or steel) or a plastics material. The seal 48 and lip seal 50 are preferably formed from elastomeric material. The seal 48 preferably has a wavy surface 52 having a maximum thickness greater than the thickness of the outer frame 44.
The inlet aperture 36, outlet aperture 38, and overflow aperture 42 are formed in the inner wall 46. In use, the seal means 28 is positioned between aligned walls 54, 56 of the end fitting 24 and the housing 14 respectively, with the outer frame 44 being positioned between the aligned walls, and at least a portion of the seal 48 being compressed between the aligned walls to substantially prevent leakage of hydraulic fluid out of the automatic transmission 10. The lip seal 50 makes a sealing engagement with the tubular extension 25 of the end fitting 24 to substantially prevent leakage of hydraulic fluid from or to the auxiliary reservoir 26.
As an example of the operation of the above described embodiment, during first and second gear ratios, when the motor vehicle 100 is either stopped (Figure 6A) or subjected to high acceleration (Figures 6B and 6C), the friction device 12' is not operational, and so hydraulic fluid 102 is not pumped to fluid line 30, and no hydraulic fluid enters the auxiliary reservoir 26.
In third gear ratio (Figure 6D), the friction device 12' is operational. The motor vehicle 100 is still subjected to acceleration but at a lower level than when the automatic transmission 10 is in first or second gear ratio. In other words, third gear ratio is lower than second gear ratio, which is lower than first gear ratio. At this stage, hydraulic fluid 102 is pumped to the friction device 12' through line 30. Hydraulic fluid 102 also passes along input fluid line 32 and through the input aperturelorifice 36 into the auxiliary reservoir 26. Hydraulic fluid 102 also passes from the auxiliary reservoir 26 by way of output aperture/orifice 38 and output fluid line 34 to the main reservoir 16, but at a slower rate than the input to the auxiliary reservoir.
The auxiliary reservoir 26 therefore fills with hydraulic fluid. If the auxiliary reservoir 26 becomes substantially full, hydraulic fluid 102 will also leave the auxiliary reservoir by way of overflow aperture 42 and overflow fluid line 40.
The volume of hydraulic fluid in the main reservoir 16 is therefore reduced, reducing the risk of temperature increases and aerating of the hydraulic fluid during operation of the automatic transmission 10 in third gear ratio.
During fourth and fifth gear ratios, the friction device 12' remains operational, and hydraulic fluid 102 remains in the auxiliary reservoir 26 (Figure 6E). The motor vehicle 100 is subjected to little or no acceleration because fourth gear ratio is lower than third gear ratio, and fifth gear ratio is lower than fourth gear ratio. The volume of hydraulic fluid 102 in the main reservoir 16 remains reduced, thereby maintaining the reduce risk of temperature increases and aerating of the hydraulic fluid during operation of the automatic transmission 10 in fourth and fifth gear ratios.
If the motor vehicle 100 is subjected to deceleration from third, fourth or fifth gear ratio (Figure 6F), the operation of friction device 12' ceases, hydraulic fluid 102 no longer enters the auxiliary reservoir 26, but drains from the auxiliary reservoir into the main reservoir 16 to increase the volume of hydraulic fluid in the main reservoir.
It will be appreciated from the above that the present invention provides an arrangement for reducing the volume of hydraulic fluid within the main reservoir 16 during operation of the automatic transmission 10 at gear ratios at or below a predetermined level. This arrangement is achieved with little modification to a known automatic transmission.
Various modifications can be made to the above described arrangement. For example, the friction device 12' may be associated with a higher or lower gear ratio than third gear ratio to provide filling of the auxiliary reservoir 26 from a higher or lower predetermined gear ratio. A float valve 58 may be positioned in the input fluid line 32 on one side of the orifice 36 (Figure 7) or the other side of the orifice. The float valve 58 is operated by the level of hydraulic fluid in the main reservoir 16 to substantially prevent the flow of hydraulic fluid to the auxiliary reservoir 26 when the level of hydraulic fluid in the main reservoir is below a predetermined level. A thermostatic valve 60 may be placed in parallel with (Figure 7) or in series with the orifice 38 in the output fluid line 34 to compensate for any temperature variations in the hydraulic fluid. In the case where the end fitting 24 does not have a tubular extension 25, the inner wall 46 of the seal means 28 is not annular but solid, and the lip seal 50 is omitted.
The input fluid line 32 may be connected to the pump 18 (instead of fluid line 30) by way of a separate solenoid valve which is operated to be open only when the gear ratio is at and below the predetermined gear ratio. The input and output apertures 36, 38 in the seal means 28 may be the same size as the associated input fluid line 32 and the output fluid line 34, respectively, with, in this case, separate restriction orifices being placed in the fluid lines.

Claims (11)

Claims
1. An automatic transmission for a motor vehicle comprising a number of friction devices operated by hydraulic fluid to provide a number of different gear ratios; a housing having a main reservoir for storing the hydraulic fluid; an end fitting attached to one end of the housing; seal means between the housing and the end fitting and defining with the end fitting an auxiliary reservoir within the end fitting; input means including a fluid passage through the seal means for transferring hydraulic fluid to the auxiliary reservoir at or below a predetermined gear ratio; and output means including a fluid passage through the seal means for transferring any hydraulic fluid in the auxiliary reservoir from the auxiliary reservoir to the main reservoir at gear ratios above the predetermined gear ratio.
2. An automatic transmission as claimed in Claim 1, wherein the input means comprises an input fluid line, and wherein the output means comprises an output fluid line, the input fluid line having a restriction orifice therein, and the output fluid line having a restriction orifice therein which is smaller in size than the restriction orifice in the input fluid line.
3. An automatic transmission as claimed in Claim 2, wherein the restriction orifice in the input fluid line is defined by the size of the fluid passage of the input means through the seal means, and wherein the restriction orifice in the output fluid line is defined by the size of the fluid passage of the output means through the seal means.
4. An automatic transmission as claimed in Claim 2 or Claim 3, wherein the input fluid line is fluidly connected to a fluid line providing hydraulic fluid to one of the friction devices, said one friction device being operational only at or below the predetermined gear ratio.
5. An automatic transmission as claimed in any one of Claims 1 to 4, further comprising overflow means including a fluid passage through the seal means for transferring hydraulic fluid from the auxiliary reservoir to the main reservoir when the auxiliary reservoir is substantially full.
6. An automatic transmission as claimed in Claim 5, wherein the overflow means comprises an overflow fluid line having a restriction orifice therein.
7. An automatic transmission as claimed in any one of Claims 1 to 6, further comprising a float valve which is operated by the level of hydraulic fluid in the main reservoir, the float valve being positioned in the input means to close the input means when the level of hydraulic fluid in the main reservoir is below a predetermined level.
8. An automatic transmission as claimed in any one of Claims 1 to 7, further comprising a thermostatic valve positioned in the output means.
9. An automatic transmission as claimed in any one of Claims 1 to 8, wherein the seal means comprises a substantially rigid outer annular frame; a substantially rigid inner wall; and a compressible seal between the outer frame and the inner wall, the seal being compressed between the end fitting and the housing.
10. An automatic transmission as claimed in any one of Claims 1 to 9, wherein the predetermined gear ratio is third gear ratio.
11. An automatic transmission substantially as herein described with reference to, and as shown in, the accompanying drawings.
GB9703462A 1997-02-19 1997-02-19 Automatic transmission Expired - Fee Related GB2322421B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9703462A GB2322421B (en) 1997-02-19 1997-02-19 Automatic transmission

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9703462A GB2322421B (en) 1997-02-19 1997-02-19 Automatic transmission

Publications (3)

Publication Number Publication Date
GB9703462D0 GB9703462D0 (en) 1997-04-09
GB2322421A true GB2322421A (en) 1998-08-26
GB2322421B GB2322421B (en) 2001-02-07

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Family Applications (1)

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GB9703462A Expired - Fee Related GB2322421B (en) 1997-02-19 1997-02-19 Automatic transmission

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2471653A (en) * 2009-06-30 2011-01-12 Meritor Technology Inc A method of controlling a fluid level around a transmission gear
FR2996177A1 (en) * 2012-09-28 2014-04-04 Poclain Hydraulics Ind VEHICLE WITH IMPROVED HYDRAULIC ASSISTANCE INTEGRATING A SYSTEM FOR MANAGING OIL LEVELS IN THE HOUSINGS OF HYDRAULIC DEVICES
DE102019218418A1 (en) * 2019-11-28 2021-06-02 Zf Friedrichshafen Ag Transmission for a motor vehicle

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217926A (en) * 1978-11-29 1980-08-19 General Motors Corporation Thermally controlled oil storage reservoir for a transmission
GB2248092A (en) * 1990-08-08 1992-03-25 Honda Motor Co Ltd System for lubricating a transmission including an auxiliary oil reservoir
EP0696697A1 (en) * 1994-08-12 1996-02-14 Toyota Jidosha Kabushiki Kaisha Device for effective lubrication of vehicle power transmission system upon starting of vehicle

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217926A (en) * 1978-11-29 1980-08-19 General Motors Corporation Thermally controlled oil storage reservoir for a transmission
GB2248092A (en) * 1990-08-08 1992-03-25 Honda Motor Co Ltd System for lubricating a transmission including an auxiliary oil reservoir
EP0696697A1 (en) * 1994-08-12 1996-02-14 Toyota Jidosha Kabushiki Kaisha Device for effective lubrication of vehicle power transmission system upon starting of vehicle

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2471653A (en) * 2009-06-30 2011-01-12 Meritor Technology Inc A method of controlling a fluid level around a transmission gear
US10502311B2 (en) 2009-06-30 2019-12-10 Meritor Technology, Inc. Method of controlling operation of a vehicle
FR2996177A1 (en) * 2012-09-28 2014-04-04 Poclain Hydraulics Ind VEHICLE WITH IMPROVED HYDRAULIC ASSISTANCE INTEGRATING A SYSTEM FOR MANAGING OIL LEVELS IN THE HOUSINGS OF HYDRAULIC DEVICES
DE102019218418A1 (en) * 2019-11-28 2021-06-02 Zf Friedrichshafen Ag Transmission for a motor vehicle

Also Published As

Publication number Publication date
GB9703462D0 (en) 1997-04-09
GB2322421B (en) 2001-02-07

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20140219