WO2009142593A1 - Device and method for control of oil temperature in a gearbox, and a gearbox - Google Patents

Device and method for control of oil temperature in a gearbox, and a gearbox Download PDF

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Publication number
WO2009142593A1
WO2009142593A1 PCT/SE2009/050574 SE2009050574W WO2009142593A1 WO 2009142593 A1 WO2009142593 A1 WO 2009142593A1 SE 2009050574 W SE2009050574 W SE 2009050574W WO 2009142593 A1 WO2009142593 A1 WO 2009142593A1
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WO
WIPO (PCT)
Prior art keywords
oil
gearbox
temperature
control
gear
Prior art date
Application number
PCT/SE2009/050574
Other languages
French (fr)
Inventor
Mårten DAHLBÄCK
Original Assignee
Scania Cv Ab
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 Scania Cv Ab filed Critical Scania Cv Ab
Publication of WO2009142593A1 publication Critical patent/WO2009142593A1/en

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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
    • F16N—LUBRICATING
    • F16N39/00—Arrangements for conditioning of lubricants in the lubricating system
    • F16N39/04—Arrangements for conditioning of lubricants in the lubricating system by heating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R17/00—Arrangements or adaptations of lubricating systems or devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
    • F01M5/00—Heating, cooling, or controlling temperature of lubricant; Lubrication means facilitating engine starting
    • F01M5/005—Controlling temperature of lubricant
    • 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
    • F16H57/0412—Cooling or heating; Control of temperature
    • F16H57/0413—Controlled cooling or heating of lubricant; Temperature control therefor
    • 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
    • F16H57/048—Type of gearings to be lubricated, cooled or heated
    • F16H57/0493—Gearings with spur or bevel gears
    • 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
    • F16N—LUBRICATING
    • F16N39/00—Arrangements for conditioning of lubricants in the lubricating system
    • 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
    • F16N—LUBRICATING
    • F16N39/00—Arrangements for conditioning of lubricants in the lubricating system
    • F16N39/02—Arrangements for conditioning of lubricants in the lubricating system by cooling
    • 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
    • F16N—LUBRICATING
    • F16N2210/00—Applications
    • F16N2210/12—Gearings

Definitions

  • the present invention relates to a device for control of oil temperature in a gearbox according to the preamble of claim 1 , a method for control of oil temperature in a gearbox according to the preamble of claim 12, and a gearbox according to the preamble of claim 10.
  • Gearboxes for heavy vehicles such as buses, trucks and work vehicles comprise usually both a main section and a high/low gear section.
  • the high/low gear section e.g. a planetary gear, makes it possible in a known manner to reutilise the main section of the gearbox with the object of having twice as many gear positions in the gearbox as are had without a high/low gear section.
  • Losses in the main section of the gearbox are substantially of two kinds, viz. gear friction losses and slippage losses, the latter also comprising splash losses.
  • the gear sets do not need lubrication and cooling to any great extent, so the so-called splash losses, i.e. unnecessary splash lubrication, are greater in this case than in gear positions in which greater amounts of torque are transmitted via the gear sets, a situation in which the gear sets therefore need good lubrication and cooling.
  • Splash losses nevertheless also occur in these latter gear positions, i.e. splash losses occur in all gear combinations.
  • Further slippage losses also occur in, for example, bearings in the gearbox. The slippage losses depend on rotation speed.
  • gear friction losses only occur in gear positions in which large amounts of torque are transmitted via the gear sets, i.e. gear friction losses do not occur in the "direct drive position" described above.
  • EP 0 736 703 A1 refers to a device which acts upon the oil temperature in a gearbox in that in an initial hot running phase, particularly after a cold start, it warms the oil until the oil reaches a set-point temperature, in order as quickly as possible to warm the oil to operating temperature, after which the oil is alternately cooled and warmed to keep it at the set-point temperature.
  • a device according to claim 1 , a method according to claim 12 and a gearbox according to claim 10 which have the characteristics that a cooling device is provided to cool the oil when a gear position is engaged in which at least some of the gear sets of the gearbox are involved in the propulsion of the vehicle, and that a heating device is provided for warming the oil when a gear position is engaged in which the main section's input shaft is directly coupled to the main section's output shaft so that they rotate at the same speed, with the gear sets uninvolved in the propulsion of the vehicle, afford respectively the advantage that the viscosity of the oil is increased, thereby reducing the risk of the gearbox suffering damage from the torque transmitted via at least one gear set, and that the viscosity of the oil is reduced, thereby reducing the slippage losses which occur in the gearbox.
  • Figure 1 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section
  • Figure 2 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a first embodiment of the invention
  • Figure 3 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a second embodiment of the invention
  • Figure 4 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a third embodiment of the invention
  • Figure 5 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a fourth embodiment of the invention
  • Figure 6 depicts schematically a flowchart of a method according to an embodiment of the invention.
  • Figure 1 depicts schematically a longitudinal section of a gearbox 2 for a vehicle 1 comprising a main section 4 and a high/low gear section 6, which gearbox 2 further comprises an input shaft 8 in the main section 4 and an output shaft 10 from the main section 4, the input shaft 12 to the high/low gear section 6 being rigidly connected to, and preferably integrated with, the output shaft 10 from the main section 4.
  • the gearbox 2 further comprises an output shaft 14 from the high/low gear section 6.
  • the gearbox may also have no high/low gear section.
  • the main section 4 of the gearbox 2 also comprises a wet sump 16, i.e an oil pan, containing oil 18, and a countershaft 20 on which a number of gearwheels 22, 24, 26, 28 are arranged, at least one gearwheel 22, 24, 26, 28 being partly immersed in the oil 18 in the wet sump 16.
  • Gearwheels 30, 32, 34, 36 are also arranged respectively on the input shaft 8 and the output shaft 10 of the main section 4. Connecting together in a known manner the input shaft 8 of the main section 4, the output shaft 10 of the main section 4 and the countershaft 20 via various combinations of the gearwheels 30, 32; 34, 36; 22, 24, 26, 28 results in various gear positions, i.e. various transmission ratios, for the main section 4 of the gearbox 2 when the gear sets 23, 25, 27, 29 are involved in the propulsion of the vehicle 1.
  • This gear position is a high gear, i.e. a gear used when travelling at high and relatively uniform velocity, e.g. on motorways, and is a gear which heavy long-distance traffic uses to a very great extent, of the order of 90% of running time.
  • At least tooth flanks K of at least one gear set gearwheel 22, 24, 26, 28; 30, 32, 34, 36 preferably those of all the gear set gearwheels which are in engagement with other gearwheels arranged on the countershaft 20 of the gearbox, can thus dip down into and pass through the oil 18 provided in the wet sump 16 to achieve gear set lubrication, good lubrication and cooling of the gear sets thus being assured by the fact that said gearwheel splashes oil up towards the gear sets when it rotates.
  • the oil level should not be too low, but too high an oil level results in large splash losses.
  • the gear sets may be adapted to driving an oil pump P which lubricates various shaft bearings, e.g. taper needle bearings, in the gearbox by supplying them with oil under pressure from the wet sump via lines (not depicted) in a known manner, which is advantageous in that the bearings need oil and are not always reached by splash lubrication.
  • an oil pump P which lubricates various shaft bearings, e.g. taper needle bearings, in the gearbox by supplying them with oil under pressure from the wet sump via lines (not depicted) in a known manner, which is advantageous in that the bearings need oil and are not always reached by splash lubrication.
  • Figure 2 depicts schematically a longitudinal section of a gearbox 2 with main section 4 and high/low gear section 6, and with a device 38 for control of the oil temperature in the gearbox 2 according to a first embodiment of the invention, in which the device 38 for control of the oil temperature comprises a cooling device 40 adapted to cooling the oil 18 when a gear position is engaged in which at least some of the gear sets 23, 25, 27, 29 are involved in the propulsion of the vehicle 1 , particularly when a large amount of torque is extracted from the gearbox 2 over a long period, in order to minimise the damage which the gearbox 2 might suffer from high torque, e.g. on its gear teeth and bearings.
  • the device 38 for control of the oil temperature comprises a cooling device 40 adapted to cooling the oil 18 when a gear position is engaged in which at least some of the gear sets 23, 25, 27, 29 are involved in the propulsion of the vehicle 1 , particularly when a large amount of torque is extracted from the gearbox 2 over a long period, in order to minimise the damage which the gearbox 2 might suffer from high torque
  • the device 38 for control of the oil temperature comprises also a warming device 42 adapted to warming the oil 18 when a gear position is engaged in which the input shaft 8 of the main section 4 is coupled to the output shaft 10 of the main section 4 so that these shafts rotate at the same speed in a "direct drive position" whereby the gear sets 23, 25, 27, 29 of the gearbox 2 do not transmit any significant torque but merely rotate with said input shaft 8 and output shaft 10 without being involved in the propulsion of the vehicle 1 , in order to minimise the slippage losses which occur in the gearbox 2.
  • Warming the oil 18 reduces its viscosity, thereby, as mentioned above, reducing the slippage losses.
  • the oil 18 which circulates in the gearbox 2 is intended to be cooled and warmed by using the aforesaid cooling device 40 and warming device 42 respectively.
  • the oil circulated by the pump P in the gearbox 2 is led to a heat exchanger 44, preferably a plate heat exchanger preferably situated outside the gearbox 2, and thereafter from the heat exchanger 44 to the lubrication points, e.g. bearings, situated in the gearbox 2.
  • An oil loop 46 is connected to an inlet 48 and an outlet 50 of the heat exchanger 44.
  • a temperature medium loop 52 is also connected to a further inlet 54 and a further outlet 56 in the heat exchanger 44, whereby the temperature of the temperature medium 58 in the temperature medium loop 52 can act upon the temperature of the oil 18 in the oil loop 46 in a manner known in heat exchangers.
  • the temperature medium 58 is preferably a liquid but may also be a gas, although the latter will be of lower efficiency in the heat exchanger.
  • the temperature of the temperature medium 58 may be lower or higher than the temperature of the oil 18, depending on whether it is intended to cool or warm the oil in the oil loop 46.
  • the temperature medium loop 52 is provided with a switching valve 60 whereby it is possible by switching the valve 60 to connect the temperature medium loop 52 either to a cooling device 40 or to a warming device 42 or steplessly to both the cooling device 40 and the warming device 42, depending on the temperature desired for the temperature medium 58.
  • the warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature
  • the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler.
  • a control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 60 for cooling device 40 and warming device 42, which switching unit 60 may for example be a valve.
  • Figure 3 depicts schematically a longitudinal section of a gearbox 2 with main section 4 and high/low gear section 6, and with a device 38 for control of the oil temperature in the gearbox 2 according to a second embodiment of the invention which differs from that depicted in Figure 2 in that the temperature medium loop is replaced by two temperature medium loops 51 , 53 connected to the heat exchanger 44 and each having a switching unit in the form of a flow control valve 59, 61 , one temperature medium loop 51 being connected to the cooling device 40 and the other temperature medium loop 53 to the warming device 42.
  • the warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature, and the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler.
  • a control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 59, 61 for cooling device 40 and warming device 42, which switching unit 60 may for example be a valve as mentioned above.
  • Figure 4 depicts schematically a longitudinal section of a gearbox 2 with main section
  • the temperature medium loop 52 is adapted to passing the oil 18 into the wet sump 16, which does however entail lower efficiency in that the oil flow past the surfaces which are cooled/heated by the temperature medium 58 will be smaller.
  • the temperature medium loop 52 serves as a primitive heat exchanger through which the oil 18 passes into the wet sump 16.
  • a heat exchanger 44 may be provided in the wet sump 16.
  • the warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature, and the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler.
  • a control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 60 for cooling device 40 and warming device 42, which switching unit 60 may for example be a valve.
  • FIG. 5 depicts schematically a longitudinal section of a gearbox 2 with main section 4 and high/low gear section 6, and with a device 38 for control of the oil temperature in the gearbox 2 according to a fourth embodiment of the invention which differs from that depicted in Figure 4 in that the temperature medium loop is replaced by two temperature medium loops 51 , 53 each having a switching unit in the form of a flow control valve 59, 61 , which temperature medium loops 51 , 53 are connected to the cooling device 40 and the warming device 42 respectively and are adapted to passing the oil 18 into the wet sump 16, which does however entail lower efficiency in that the oil flow past the surfaces which are cooled/heated by the temperature medium 58 will be smaller.
  • the temperature medium loops 51 , 53 serve as primitive heat exchangers through which the oil 18 passes into the wet sump 16.
  • a heat exchanger 44 may be provided in the wet sump 16.
  • the warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature, and the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler.
  • a control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 59, 61 for cooling device 40 and warming device 42, which switching unit 59, 61 may for example be a valve as mentioned above.
  • Figure 6 depicts schematically a flowchart of a method according to an embodiment of the invention. The method comprises the steps:
  • the invention comprises a device for control of the oil temperature whereby either the oil in the gearbox is led out from the gearbox for cooling/warming of the oil, or a temperature medium is led into the gearbox to cool/warm the oil, or these media transfer cold/heat through the gearbox wall, e.g. by means of a heat exchanger arranged at the gearbox wall.

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

Abstract

The invention relates to a device for control of oil temperature in a gearbox (2), in which a cooling device (40) and a warming device (42) are thermally associated with the oil (18) in the gearbox (2) via at least one temperature medium loop (51, 52, 53), the gearbox (2) comprises at least one main section (4) with input shaft (8), output shaft (10), counter shaft (20) and gear sets (23, 25, 27, 29) which can connect the input shaft (8) and the output shaft (10) together via the counter shaft (20), the cooling device (40) is adapted to cooling the oil when a gear position is engaged in which at least some of the gear sets (23, 25, 27, 29) are involved in the propulsion of the vehicle (1), in order to increase the viscosity of the oil and hence reduce the risk of the gearbox suffering damage from the torque transmitted via at least one gear set (23, 25, 27, 29), and the warming device (42) is adapted to warming the oil when a gear position is engaged in which the input shaft (8) of the main section (4) is directly coupled to the output shaft (10) of the main section (4) so that these shafts rotate at the same speed while the gear sets (23, 25, 27, 29) are uninvolved in the propulsion of the vehicle (1), in order to reduce the viscosity of the oil and hence reduce the slippage losses which occur in the gearbox. The invention relates also to a gearbox (2) and a method for control of oil temperature in a gearbox (2).

Description

DEVICE AND METHOD FOR CONTROL OF OIL TEMPERATURE IN A GEARBOX, AND A GEARBOX
Technical field
The present invention relates to a device for control of oil temperature in a gearbox according to the preamble of claim 1 , a method for control of oil temperature in a gearbox according to the preamble of claim 12, and a gearbox according to the preamble of claim 10.
Background
Vehicles such as passenger cars, buses, trucks and work vehicles are provided with gearboxes to make it possible to use just one engine to power the vehicle at both low and high velocities and at the same time keep the speed of the engine within a suitable working range. Gearboxes for heavy vehicles such as buses, trucks and work vehicles comprise usually both a main section and a high/low gear section. The high/low gear section, e.g. a planetary gear, makes it possible in a known manner to reutilise the main section of the gearbox with the object of having twice as many gear positions in the gearbox as are had without a high/low gear section.
Losses in the main section of the gearbox are substantially of two kinds, viz. gear friction losses and slippage losses, the latter also comprising splash losses.
During vehicle movement at velocities at which such a high gear is used that the input shaft and output shaft in the main section of the gearbox run at the same rotation speed, i.e. these shafts are coupled to one another in a so-called "direct drive position", no great amounts of torque are transmitted via gear sets of the gearbox, since the gear sets are uninvolved in the propulsion of the vehicle. The gear sets merely rotate with said input and output shafts and throw oil around in the gearbox to lubricate the gear sets, since in said gear position the gear set gearwheels arranged on the countershaft of the gearbox dip down into a so-called wet sump which contains oil. However, the gear sets do not need lubrication and cooling to any great extent, so the so-called splash losses, i.e. unnecessary splash lubrication, are greater in this case than in gear positions in which greater amounts of torque are transmitted via the gear sets, a situation in which the gear sets therefore need good lubrication and cooling. Splash losses nevertheless also occur in these latter gear positions, i.e. splash losses occur in all gear combinations. Further slippage losses also occur in, for example, bearings in the gearbox. The slippage losses depend on rotation speed.
Unlike slippage losses, gear friction losses only occur in gear positions in which large amounts of torque are transmitted via the gear sets, i.e. gear friction losses do not occur in the "direct drive position" described above.
Slippage losses increase with higher viscosity of the oil, so it is desirable for the oil to be at as low viscosity as possible. However, lower viscosity of the oil is a problem in that it increases the risk of surface damage to gear teeth and bearings in the gearbox. Lower viscosity of the oil leads to fuel savings, whereas higher viscosity of the oil leads to longer service life of gear teeth and bearings in the gearbox or to the possibility of loading the gearbox with higher torque. Thus the choice of the viscosity of the oil in a gearbox represents a compromise between these two incompatible desiderata.
EP 0 736 703 A1 refers to a device which acts upon the oil temperature in a gearbox in that in an initial hot running phase, particularly after a cold start, it warms the oil until the oil reaches a set-point temperature, in order as quickly as possible to warm the oil to operating temperature, after which the oil is alternately cooled and warmed to keep it at the set-point temperature.
Brief description of the invention
The problem that the choice of the viscosity of the oil in a gearbox represents a compromise between achieving low enough viscosity to minimise slippage losses in the gearbox and high enough viscosity to maximise the permissible level of torque in the gearbox is solved according to the invention by a device for control of the oil temperature in a gearbox according to the characterising part of claim 1 , by a method for control of the oil temperature in a gearbox according to the characterising part of claim 12, and by a gearbox according to the characterising part of claim 10.
A device according to claim 1 , a method according to claim 12 and a gearbox according to claim 10 which have the characteristics that a cooling device is provided to cool the oil when a gear position is engaged in which at least some of the gear sets of the gearbox are involved in the propulsion of the vehicle, and that a heating device is provided for warming the oil when a gear position is engaged in which the main section's input shaft is directly coupled to the main section's output shaft so that they rotate at the same speed, with the gear sets uninvolved in the propulsion of the vehicle, afford respectively the advantage that the viscosity of the oil is increased, thereby reducing the risk of the gearbox suffering damage from the torque transmitted via at least one gear set, and that the viscosity of the oil is reduced, thereby reducing the slippage losses which occur in the gearbox.
Brief description of the drawings
The invention is explained in more detail below with reference to the attached drawings, in which:
Figure 1 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section,
Figure 2 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a first embodiment of the invention, Figure 3 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a second embodiment of the invention,
Figure 4 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a third embodiment of the invention,
Figure 5 depicts schematically a longitudinal section of a gearbox with main section and high/low gear section and with a device for control of the oil temperature in a gearbox according to a fourth embodiment of the invention, and
Figure 6 depicts schematically a flowchart of a method according to an embodiment of the invention.
Description of preferred embodiments
Similar items in the various diagrams are designated by the same reference notations.
Figure 1 depicts schematically a longitudinal section of a gearbox 2 for a vehicle 1 comprising a main section 4 and a high/low gear section 6, which gearbox 2 further comprises an input shaft 8 in the main section 4 and an output shaft 10 from the main section 4, the input shaft 12 to the high/low gear section 6 being rigidly connected to, and preferably integrated with, the output shaft 10 from the main section 4. The gearbox 2 further comprises an output shaft 14 from the high/low gear section 6. The gearbox may also have no high/low gear section.
As may be seen in the diagram, the main section 4 of the gearbox 2 also comprises a wet sump 16, i.e an oil pan, containing oil 18, and a countershaft 20 on which a number of gearwheels 22, 24, 26, 28 are arranged, at least one gearwheel 22, 24, 26, 28 being partly immersed in the oil 18 in the wet sump 16. Gearwheels 30, 32, 34, 36 are also arranged respectively on the input shaft 8 and the output shaft 10 of the main section 4. Connecting together in a known manner the input shaft 8 of the main section 4, the output shaft 10 of the main section 4 and the countershaft 20 via various combinations of the gearwheels 30, 32; 34, 36; 22, 24, 26, 28 results in various gear positions, i.e. various transmission ratios, for the main section 4 of the gearbox 2 when the gear sets 23, 25, 27, 29 are involved in the propulsion of the vehicle 1.
It is also possible to couple the input shaft 8 of the main section 4 directly to the output shaft 10 of the main section 4 via a connecting device 9 whereby these shafts rotate at the same speed, in which gear position the gearwheels 22, 24, 26, 28 arranged on the countershaft 20 do not transmit a significant amount of torque, since the gear sets 23, 25, 27, 29 of the gearbox then merely rotate with said input shaft 8 and output shaft 10 without being involved in the propulsion of the vehicle 1. This gear position is a high gear, i.e. a gear used when travelling at high and relatively uniform velocity, e.g. on motorways, and is a gear which heavy long-distance traffic uses to a very great extent, of the order of 90% of running time. In a traditional gearbox, in this gear position at least one gearwheel 22, 24, 26, 28 arranged on the countershaft 20 throws oil around in the gearbox 2 to lubricate the gear sets 23, 25, 27, 29 despite the fact that no great amount of lubrication of the gear sets 23, 25, 27, 29 is required in said gear position, since at least one of the gear set gearwheels 22, 24, 26, 28 arranged on the countershaft 20 of the gearbox dips down into the wet sump 16 which contains oil 18. This "unnecessary" lubrication is called splash losses and increases the fuel consumption of the vehicle 1 by several percent, which is disadvantageous, particularly for heavy long-distance traffic, which to a large extent uses this gear position, as mentioned above.
At least tooth flanks K of at least one gear set gearwheel 22, 24, 26, 28; 30, 32, 34, 36, preferably those of all the gear set gearwheels which are in engagement with other gearwheels arranged on the countershaft 20 of the gearbox, can thus dip down into and pass through the oil 18 provided in the wet sump 16 to achieve gear set lubrication, good lubrication and cooling of the gear sets thus being assured by the fact that said gearwheel splashes oil up towards the gear sets when it rotates. For good lubrication and cooling, the oil level should not be too low, but too high an oil level results in large splash losses. Preferably it is only the gear sets and their gearwheel flanks which are cooled by the aforesaid splash lubrication from the wet sump. The gear sets may be adapted to driving an oil pump P which lubricates various shaft bearings, e.g. taper needle bearings, in the gearbox by supplying them with oil under pressure from the wet sump via lines (not depicted) in a known manner, which is advantageous in that the bearings need oil and are not always reached by splash lubrication.
Figure 2 depicts schematically a longitudinal section of a gearbox 2 with main section 4 and high/low gear section 6, and with a device 38 for control of the oil temperature in the gearbox 2 according to a first embodiment of the invention, in which the device 38 for control of the oil temperature comprises a cooling device 40 adapted to cooling the oil 18 when a gear position is engaged in which at least some of the gear sets 23, 25, 27, 29 are involved in the propulsion of the vehicle 1 , particularly when a large amount of torque is extracted from the gearbox 2 over a long period, in order to minimise the damage which the gearbox 2 might suffer from high torque, e.g. on its gear teeth and bearings. Cooling the oil 18 increases its viscosity, thereby reducing, as mentioned above, the risk of surface damage to gear teeth and bearings. The device 38 for control of the oil temperature comprises also a warming device 42 adapted to warming the oil 18 when a gear position is engaged in which the input shaft 8 of the main section 4 is coupled to the output shaft 10 of the main section 4 so that these shafts rotate at the same speed in a "direct drive position" whereby the gear sets 23, 25, 27, 29 of the gearbox 2 do not transmit any significant torque but merely rotate with said input shaft 8 and output shaft 10 without being involved in the propulsion of the vehicle 1 , in order to minimise the slippage losses which occur in the gearbox 2. Warming the oil 18 reduces its viscosity, thereby, as mentioned above, reducing the slippage losses.
The oil 18 which circulates in the gearbox 2 is intended to be cooled and warmed by using the aforesaid cooling device 40 and warming device 42 respectively. According to this embodiment, the oil circulated by the pump P in the gearbox 2 is led to a heat exchanger 44, preferably a plate heat exchanger preferably situated outside the gearbox 2, and thereafter from the heat exchanger 44 to the lubrication points, e.g. bearings, situated in the gearbox 2. An oil loop 46 is connected to an inlet 48 and an outlet 50 of the heat exchanger 44. According to this embodiment, a temperature medium loop 52 is also connected to a further inlet 54 and a further outlet 56 in the heat exchanger 44, whereby the temperature of the temperature medium 58 in the temperature medium loop 52 can act upon the temperature of the oil 18 in the oil loop 46 in a manner known in heat exchangers.
The temperature medium 58 is preferably a liquid but may also be a gas, although the latter will be of lower efficiency in the heat exchanger.
The temperature of the temperature medium 58 may be lower or higher than the temperature of the oil 18, depending on whether it is intended to cool or warm the oil in the oil loop 46.
According to this embodiment, the temperature medium loop 52 is provided with a switching valve 60 whereby it is possible by switching the valve 60 to connect the temperature medium loop 52 either to a cooling device 40 or to a warming device 42 or steplessly to both the cooling device 40 and the warming device 42, depending on the temperature desired for the temperature medium 58. The warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature, and the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler.
A control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 60 for cooling device 40 and warming device 42, which switching unit 60 may for example be a valve.
Figure 3 depicts schematically a longitudinal section of a gearbox 2 with main section 4 and high/low gear section 6, and with a device 38 for control of the oil temperature in the gearbox 2 according to a second embodiment of the invention which differs from that depicted in Figure 2 in that the temperature medium loop is replaced by two temperature medium loops 51 , 53 connected to the heat exchanger 44 and each having a switching unit in the form of a flow control valve 59, 61 , one temperature medium loop 51 being connected to the cooling device 40 and the other temperature medium loop 53 to the warming device 42.
The warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature, and the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler. A control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 59, 61 for cooling device 40 and warming device 42, which switching unit 60 may for example be a valve as mentioned above.
Figure 4 depicts schematically a longitudinal section of a gearbox 2 with main section
4 and high/low gear section 6, and with a device 38 for control of the oil temperature in the gearbox 2 according to a third embodiment of the invention which differs from that depicted in Figure 2 in that the temperature medium loop 52 is adapted to passing the oil 18 into the wet sump 16, which does however entail lower efficiency in that the oil flow past the surfaces which are cooled/heated by the temperature medium 58 will be smaller. The temperature medium loop 52 serves as a primitive heat exchanger through which the oil 18 passes into the wet sump 16. Alternatively, a heat exchanger 44 may be provided in the wet sump 16.
The warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature, and the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler. A control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 60 for cooling device 40 and warming device 42, which switching unit 60 may for example be a valve.
Figure 5 depicts schematically a longitudinal section of a gearbox 2 with main section 4 and high/low gear section 6, and with a device 38 for control of the oil temperature in the gearbox 2 according to a fourth embodiment of the invention which differs from that depicted in Figure 4 in that the temperature medium loop is replaced by two temperature medium loops 51 , 53 each having a switching unit in the form of a flow control valve 59, 61 , which temperature medium loops 51 , 53 are connected to the cooling device 40 and the warming device 42 respectively and are adapted to passing the oil 18 into the wet sump 16, which does however entail lower efficiency in that the oil flow past the surfaces which are cooled/heated by the temperature medium 58 will be smaller. The temperature medium loops 51 , 53 serve as primitive heat exchangers through which the oil 18 passes into the wet sump 16. Alternatively, a heat exchanger 44 may be provided in the wet sump 16.
The warming device 42 preferably extracts heat from the exhaust gases of the vehicle engine 43 via, for example, a heat exchanger situated in the exhaust pipe or the manifold when it is preferably desired to raise the temperature above the radiator liquid temperature, and the cooling device 40 preferably extracts cold from the vehicle's ordinary cooling package 41 comprising, for example, engine radiator, intercooler and what is preferably an air-type oil cooler or two-stage water cooler. A control unit 62 is provided to control the connection and disconnection of the cooling device 40 and the warming device 42 on the basis of current gear position, by receiving input signals from a gear position detector 64 and sending control signals to at least one switching unit 59, 61 for cooling device 40 and warming device 42, which switching unit 59, 61 may for example be a valve as mentioned above.
Figure 6 depicts schematically a flowchart of a method according to an embodiment of the invention. The method comprises the steps:
- of connecting the cooling device 40 to cool the oil when a gear position is engaged in which at least some of the gear sets 23, 25, 27, 29 are involved in the propulsion of the vehicle 1 , in order to increase the viscosity of the oil and hence reduce the risk of the gearbox suffering damage from the torque transmitted via at least one gear set 23, 25, 27, 29, and
- of connecting the warming device 42 to warm the oil when a gear position is engaged in which the input shaft 8 of the main section 4 is directly coupled to the output shaft 10 of the main section 4 so that these shafts rotate at the same speed while the gear sets 23, 25, 27, 29 are uninvolved in the propulsion of the vehicle 1 , in order to reduce the viscosity of the oil and hence reduce the slippage losses which occur in the gearbox.
The invention comprises a device for control of the oil temperature whereby either the oil in the gearbox is led out from the gearbox for cooling/warming of the oil, or a temperature medium is led into the gearbox to cool/warm the oil, or these media transfer cold/heat through the gearbox wall, e.g. by means of a heat exchanger arranged at the gearbox wall.

Claims

Claims
1. A device for control of oil temperature in a gearbox (2), the device (38) comprising a cooling device (40) and a warming device (42) which are thermally associated with the oil (18) in the gearbox (2) via at least one temperature medium loop (51 ,
52, 53), characterised in that the gearbox (2) comprises at least one main section (4) with input shaft (8), output shaft (10), countershaft (20) and gear sets (23, 25, 27, 29) which can connect the input shaft (8) and the output shaft (10) together via the countershaft (20), that the cooling device (40) is adapted to cooling the oil when a gear position is engaged in which at least some of the gear sets (23, 25, 27, 29) are involved in the propulsion of the vehicle (1 ), in order to increase the viscosity of the oil and hence reduce the risk of the gearbox suffering damage from the torque transmitted via at least one gear set (23, 25, 27, 29), and that the warming device (42) is adapted to warming the oil when a gear position is engaged in which the input shaft (8) of the main section (4) is directly coupled to the output shaft (10) of the main section (4) so that these shafts rotate at the same speed while the gear sets (23, 25, 27, 29) are uninvolved in the propulsion of the vehicle (1 ), in order to reduce the viscosity of the oil and hence reduce the slippage losses which occur in the gearbox.
2. A device for control of oil temperature according to claim 1 , characterised in that the oil circulating in the gearbox (2) is intended to be led in an oil loop (46) to a heat exchanger (44) and thereafter from the heat exchanger (44) to the lubrication points situated in the gearbox (2), and that a temperature medium loop (52) is connected to the heat exchanger (44) and to the cooling device (40) and the warming device (42) so that the temperature of the temperature medium (58) in the temperature medium loop (52) can act upon the temperature of the oil (18) in the oil loop (46).
3. A device for control of oil temperature according to claim 2, characterised in that the temperature medium loop (52) is provided with a switching unit (60) whereby it is possible by switching the switching unit (60) to connect the temperature medium loop (52) to the cooling device (40) or the warming device (42).
4. A device for control of oil temperature according to claim 1 , characterised in that the oil circulating in the gearbox (2) is intended to be led in an oil loop (46) to a heat exchanger (44) and thereafter from the heat exchanger (44) to the lubrication points situated in the gearbox (2), that a temperature medium loop (51 ) is connected to the heat exchanger (44) and to the cooling device (40) and that a further temperature medium loop (53) is connected to the heat exchanger (44) and to the warming device (42) so that the temperature of the temperature medium (58) in the respective temperature medium loop (51 , 53) can act upon the temperature of the oil (18) in the oil loop (46).
5. A device for control of oil temperature according to claim 1 , characterised in that a temperature medium loop (52) is connected to the cooling device (40) and the warming device (42) and that the temperature medium loop (52) is adapted to passing the oil (18) into the wet sump (16), whereby the temperature medium loop (52) serves as a heat exchanger through which the oil (18) passes into the wet sump (16).
6. A device for control of oil temperature according to claim 1 , characterised in that a temperature medium loop (51 ) is connected to the cooling device (40) and that a further temperature medium loop (53) is connected to the warming device (42), which temperature medium loops (51 , 53) are adapted to passing the oil (18) into the wet sump (16), whereby the temperature medium loops (51 , 53) serve as heat exchangers through which the oil (18) passes into the wet sump (16).
7. A device for control of oil temperature according to any one of the foregoing claims, characterised in that a control unit (62) is adapted to controlling the connection and disconnection of the cooling device (40) and the warming device
(42) on the basis of current gear position, by receiving input signals from a gear position detector (64) and sending control signals to at least one switching unit (59, 60, 61 ) for cooling device (40) and warming device (42).
8. A device for control of oil temperature according to any one of the foregoing claims, characterised in that the warming device (42) extracts heat from the exhaust gases of the vehicle engine (43) and that the cooling device (40) extracts cold from the vehicle's ordinary cooling package (41 ).
9. A device for control of oil temperature according to any one of the foregoing claims, characterised in that the temperature medium (58) is a liquid or a gas.
10. A gearbox characterised in that the gearbox (2) comprises a device for control of oil temperature in a gearbox (2) according to any one of the foregoing claims.
11.A gearbox according to claim 10, characterised in that the gearbox (2) comprises a main section (4) and a high/low gear section (6).
12.A method for control of oil temperature in a gearbox (2), whereby a device (38) for control of oil temperature in a gearbox (2) comprises a cooling device (40) and a warming device (42) which are thermally associated with the oil (18) in the gearbox (2) via at least one temperature medium loop (51 , 52, 53), which gearbox (2) comprises at least one main section (4) with input shaft (8), output shaft (10), countershaft (20) and gear sets (23, 25, 27, 29) which can connect the input shaft (8) and the output shaft (10) together via the countershaft (20), characterised by the steps:
- of connecting the cooling device (40) to cool the oil when a gear position is engaged in which at least some of the gear sets (23, 25, 27, 29) are involved in the propulsion of the vehicle (1 ), in order to increase the viscosity of the oil and hence reduce the risk of the gearbox suffering damage from the torque transmitted via at least one gear set (23, 25, 27, 29), and
- of connecting the warming device (42) to warm the oil when a gear position is engaged in which the input shaft (8) of the main section (4) is directly coupled to the output shaft (10) of the main section (4) so that these shafts rotate at the same speed while the gear sets (23, 25, 27, 29) are uninvolved in the propulsion of the vehicle (1 ), in order to reduce the viscosity of the oil and hence reduce the slippage losses which occur in the gearbox (2).
PCT/SE2009/050574 2008-05-23 2009-05-20 Device and method for control of oil temperature in a gearbox, and a gearbox WO2009142593A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0801213-0 2008-05-23
SE0801213A SE532421C2 (en) 2008-05-23 2008-05-23 Apparatus and method for controlling the oil temperature of a gearbox and a gearbox

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CN107061707A (en) * 2017-04-11 2017-08-18 成都工业学院 A kind of gear-box with cooling device
CN114645934A (en) * 2022-03-17 2022-06-21 安徽理工大学 Heat dissipation device for automatic gearbox and use method thereof
CN117967769A (en) * 2024-04-01 2024-05-03 江苏顺丰铝业有限公司 Anti-loosening strong-heat-dissipation gear box shell and heat dissipation method thereof

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CN107061707A (en) * 2017-04-11 2017-08-18 成都工业学院 A kind of gear-box with cooling device
CN114645934A (en) * 2022-03-17 2022-06-21 安徽理工大学 Heat dissipation device for automatic gearbox and use method thereof
CN117967769A (en) * 2024-04-01 2024-05-03 江苏顺丰铝业有限公司 Anti-loosening strong-heat-dissipation gear box shell and heat dissipation method thereof
CN117967769B (en) * 2024-04-01 2024-05-28 江苏顺丰铝业有限公司 Anti-loosening strong-heat-dissipation gear box shell and heat dissipation method thereof

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