SE537473C2 - System for lubricating and cooling a gearbox and method for controlling a flow of gearbox oil of such a system - Google Patents

Abstract

SUMMARY System for lubrication and cooling of a gearbox (1) provided with synchronizing couplings, which system (10) comprises: - an oil line (11) connected to oil channels (12) in the gearbox, - an oil pump arranged in the oil line (13), - a cooling device (14) connected to the oil line, - an electric motor (19) for driving the oil pump, and - an electronic control device (20) for controlling the speed of the electric motor. When a gear shift for changing gear in the gearbox has been initiated or is intended to be initiated, the electronic control device controls the speed of the electric motor to temporarily increase from a normal speed level to an increased speed level in order to achieve a temporary increased volume flow of gear oil and thereby a temporarily increased cooling effect of the gear oil flowing through the oil channels. The invention also relates to a method for controlling a flood of gear oil in such a system.

Description

FIELD OF THE INVENTION AND PRIOR ART The present invention relates to a system according to the preamble of claim 1 for lubrication and cooling of a gearbox provided with synchronization with synchronization. a method for controlling a flood of gear oil in such a system. The invention also relates to a computer program and a computer program product comprising computer program code for implementing a method according to the invention, as well as an electronic control unit.

In order to reduce the grouting and thereby prolong the life of various components in a gearbox, these components are lubricated with the help of gearbox oil. The oil system of a gearbox in a motor vehicle usually comprises an oil pump in the form of a rotor-type displacement pump which is connected to a side shaft of the gearbox to be driven by it, the oil pump pump rotor being driven to rotate at the same speed as the side shaft. From an oil sump at the bottom of the gearbox, the gear oil is sucked up by the oil pump to be fed through oil channels in the gearbox, after which the gear oil flows back down into the oil sump. Some types of gearboxes are provided with synchronizing couplings which are activated in connection with a change of gearbox in the gearbox to achieve a synchronous rotational speed having two components which are to be brought into rotationally engaged engagement with each other in the gearing operation. These synchronizing couplings emit frictional heat when they are active and they need to be cooled to reduce wear and thereby extend the life of the synchronizing couplings. The required cooling of the synchronizing couplings takes place with the aid of the circulating gear oil, which is caused to flow past the synchronizing couplings in order to dissipate heat from them. To improve the cooling shape of the transmission oil, the transmission oil can be passed through an oil cooler before it is led into the oil channels in the transmission. OBJECT OF THE INVENTION The object of the present invention is to provide a new and advantageous way of controlling the flow of gearbox oil in a gearbox which is provided with synchronizing couplings.

SUMMARY OF THE INVENTION According to the present invention, said object is achieved with the aid of a system having the features defined in claim 1.

The system according to the invention comprises: - an oil line connected to oil channels in the gearbox to allow gear oil to be supplied from the oil line to said oil channels for lubrication and cooling of bearings and synchronizing connections inside the gearbox, - an oil pump for generating a wax oil through flow the oil line in the direction of said oil ducts, - a cooling device connected to the oil line for cooling the gear oil, - an electric motor for driving the oil pump, and 2 - an electronic control device for controlling the speed of the electric motor.

The electronic control device is arranged to control the speed of the electric motor to temporarily increase from a normal speed level to an increased speed level when it receives information indicating that a shifting process for changing gear in the gearbox has been initiated or is intended to be initiated. The increase in speed of the electric motor leads to a corresponding increase in speed of the oil pump and thus to a temporary increased volume flow of alternating oil in the oil line and in said oil channels during the shifting process, whereby a temporary cooling effect of the alternating oil flowing through the oil channels. The increased volume flow of gearbox oil during the shifting process causes the gearbox oil to be able to dissipate frictional heat from the synchronizing couplings inside the gearbox, which in turn provides an improved cooling of the synchronizing couplings and thereby an increased service life of these.

According to an embodiment of the invention, the electronic control device is arranged to control the electric motor at said temporary increase in speed to assume a speed corresponding to a predetermined fixed drilling value. As a result, the solution according to the invention can be implemented in a relatively simple manner.

According to another embodiment of the invention, the electronic control device is arranged to control the electric motor at said temporary increase in speed to assume a speed corresponding to a drilling value calculated by the electronic control device based on a predetermined calculation model. As a result, the speed of the electric motor and thereby the speed of the oil pump can be regulated on the basis of pre-determined criteria so that the volume flow of gear oil during different shifting processes is adjusted depending on the cooling effect required for each shifting process.

Other advantageous features of the system according to the invention appear from the dependent claims and the following description.

The invention also relates to a method having the features defined in claim 7 for controlling a flood of gearbox oil in a system for lubrication and cooling of a gearbox provided with synchronizing couplings.

Other advantageous features of the method according to the invention appear from the dependent claims and the following description.

The invention also relates to a computer program having the features defined in claim 13, a computer program product having the features defined in claim 14 and an electronic control unit having the features defined in claim 15. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with the aid of exemplary embodiments, with reference to the accompanying drawings. It is shown in: Fig. 1 a schematic diagram of a system according to an embodiment of the present invention, Fig. 2 a schematic diagram of an electronic control unit for implementing a method according to the invention, and Fig. 3 a river diagram illustrating a method according to an embodiment of the invention. DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION Fig. 1 very schematically illustrates a gearbox 1 for a motor vehicle. The gearbox 1 is provided with synchronizing couplings 2, 2 ', 2 "of a per se known type which are controlled by an electronic control unit 3.

The gearbox 1 can for instance comprise a number of synchronizing couplings 2, each of which is arranged for coupling a rotating shaft in the gearbox 1 with a gear which is rotatably mounted on the current shaft. When such a synchronizing clutch 2 is activated by the control unit 3 in connection with a shifting process, the gearbox is changed in the gearbox 1, the synchronizing clutch 2 is arranged to provide a synchronous rotational speed of a rotating shaft and a gear rotatably mounted on the shaft before they are engaged in rotatable engagement. together. Said shaft may, for example, constitute an input shaft, a side shaft or a main shaft of the gearbox 1.

The gearbox 1 may also comprise a synchronizing coupling 2 '30 which is arranged for inboard connection of an integral shaft and a main shaft of the gearbox when in connection with a change of gear in the gearbox a direct connection is to be established between these shafts. When this synchronizing clutch 2 'is activated by the control unit 3 in connection with a shifting process of changing gear in the gearbox 1, the synchronizing clutch 2' is arranged to achieve a synchronous rotational speed of the input shaft and the main shaft before they are brought into rotational engagement with each other.

In the case where the gearbox 1 comprises a range gear unit with a planetary gear, the gearbox 1 may also comprise a synchronizing clutch 2 "which is arranged to act on a ring gear of said planetary gear in connection with a change of gear bearing in the range gear unit between a bearing range shaft bearing and a high range shaft bearing. the ring gear is rotatably coupled to a first coupling member which is rotatably connected to the gearbox housing of the gearbox and in the hogrange shaft layer the ring gear is rotatably coupled to a second coupling member which is rotatably connected to the main shaft of the gearbox. When this synchronizing coupling 2 gear bearing in the range gear unit from the bearing gear shaft bearing to the high gear shaft bearing, the synchronizing clutch 2 "is arranged to provide a synchronous rotational speed of the ring gear and said other coupling means before they are brought into rotationally engaged engagement with each other.

When this synchronizing clutch 2 "is activated by the control unit 3 in connection with a change of gear bearing in the range gear unit from the hagrange shaft layer to the bearing range shaft, the synchronizing clutch 2" is arranged to brake the ring gear to a standstill before the ring wheel is brought into torque with said first coupling means. The gearbox 1 has an input shaft 4 which can be connected via a coupling device 5 to a drive shaft 6 of a drive motor 7. With the aid of the coupling device 5 the input shaft 4 of the gearbox can be brought into force-transmitting connection with and disconnected from said drive shaft 6. The drive motor 7 can is caused by an internal combustion engine.

Fig. 1 illustrates a system 10 for lubricating and cooling the gearbox 1. This system 10 comprises an oil line 11 which is connected to oil channels 12 in the gearbox to allow gear oil 6 to be fed from the oil line 11 to said oil channels 12 for lubrication. and cooling of bearings and synchronizing couplings 2, 2 ', 2 "inside the gearbox 1. The system 10 further comprises an oil pump 13 in the form of a rotor-type displacement pump for generating a flow of gear oil through the oil line 11 in the direction of said oil channels 12. A cooling device 14 in the form of a conventional oil cooler is connected to the oil line 11 for cooling the gear oil.The cooling device 14 is connected in the oil line 11 between the oil pump 13 and said oil ducts 12. A thermostat 15 is arranged in the oil line 11 between the oil pump 13 and the cooling device 14. Depending on the temperature of the gearbox oil flowing in the oil line 11, the thermostat 15 directs the gearbox oil to the cooling device a 14 for cooling in it before the gear oil is passed on to the oil channels 12 in the gearbox or directly to these oil channels 12 via a bypass line 16 without passage through the cooling device 14. An oil filter 17 of conventional type is arranged in the oil line 11 between the oil pump 13 and the thermostat 15 for filtering the gear oil flowing through the oil line 11. An oil sump 18 is arranged at the bottom of the gearbox 7 1. From this oil sump 18, gear oil is sucked up by the oil pump 13 to be fed through the oil line 11. After its passage through the oil channels 12 in the gearbox 1, the gear oil runs back down into the oil sump 18.

The system 10 comprises an electric motor 19 for driving the oil pump 13 and an electronic control device 20 for controlling the speed of the electric motor 19. The electronic control device 20 is arranged to receive, for example from the control unit 3, information indicating when a shifting process for replacement of gear in gearbox 1 has been initiated or is intended to be initiated.

In a normal case, when the electronic control device 20 has not received any information indicating that a changeover process for changing gear in the gearbox 1 has been initiated or is intended to be initiated, the electronic control device 20 is arranged to control the speed of the electric motor 19 according to a speed level which has the name normal speed level. When the electronic control device 20 controls the electric motor 19 according to the normal variable level, the electronic control device 20 may, for example, be arranged to determine the desired speed N for the electric motor 19 according to the following formula: NN = 9 Rs days: N is the desired speed for the electric motor 19, N 'g is the speed of the drive shaft 6 of the drive motor, and Rs is the gear ratio of a split gear unit included in the gearbox 1. When the electronic control device 20 from the control unit 3 receives information indicating that a shifting process of changing gear in the gearbox 1 has been initiated or is intended to be initiated, the electronic control device 20 is arranged to generate a temporal speed increase of the electric motor 19 as that the speed of the electric motor temporarily increases from the normal speed level to an increased speed level in order to thereby produce a temporary increased volume flow of gear oil in the oil line 11 and in said oil channels 12 during the shifting process and thereby a temporarily increased cooling effect in the cooling channel. 12 flowing gear oil. As a result, an improved cooling of the synchronizing couplings 2, 2 ', 2 "is obtained during the switching process.

According to a first alternative, the electronic control device 15 is arranged to control the electric motor 19 at said temporary increase in speed to assume a speed corresponding to a predetermined fixed drilling value, which advantageously corresponds to a predetermined value of the maximum permitted speed of the electric motor 19. .

According to a second alternative, the electronic control device 20 is arranged to control the electric motor 19 at said temporary speed increase to assume a speed corresponding to a drill value N calc which is calculated by the electronic control device 20 starting from a predetermined calculation model. The electronic control device 20 may, for example, be arranged to determine the latter drilling value Ncaic according to the following form !: 9 / max (Neng 1 - R „IIN„ 9 Rsp IIR „• Rum Dref Nma,„ D Ncatc = min max N er Nina, min (Rsp, Rs71) 1I days: Ncalc is the calculated drill value for the speed of the electric motor 19, N e „g is the speed of the drive shaft of the drive motor 6, N main is the speed of the main shaft of the gearbox, Nina, is the maximum permissible speed for the electric motor the motor 19, R „is the gear ratio of the split gear unit for the new gear intended to be engaged during the current gearing process, Rsp is the gear ratio of the split gear unit for the last gear engaged, is the gear ratio of the main gear unit of the gear unit for the new gear intended to be engaged in during the current shifting process, and D, 1 is a predetermined reference speed difference, which may be set to 1000 rpm, for example.

The above formulas are based on a case where the oil pump 13 is driven by the electric motor 19 without an intermediate gear unit, i.e. where the oil pump pump rotor rotates at the same speed as the output shaft 21 of the electric motor 19. In a case where a gear unit is arranged between the electric motor 19 and the oil pump 13, the above formulas can be supplemented with a constant representing the gear ratio between the output shaft of the electric motor and the pump rotor of the oil pump.

After the above speed increase is performed, the electronic control device 20 is arranged to control the speed of the electric motor 10 to be reduced from the increased speed level to the normal speed level when the electronic control device 20 determines that a predetermined condition is met. According to a first alternative, the electronic control device 20 is arranged to control the speed of the electric motor to be reduced from the elevated speed level to the normal speed level when the electronic control device 20 determines that a given time has elapsed since the time when the electronic control device 20 initiated the temporary the speed increase. According to a second alternative, the electronic control device 20 is arranged to control the speed of the electric motor to be reduced from the increased speed level to the normal speed level when the electronic control device 20 has determined that the current shifting process has been completed, for example by receiving information indicating this.

The above-mentioned electronic control device 20 may be implemented by means of a single electronic control unit of the motor vehicle, as illustrated in Fig. 1. However, the electronic control device 20 could alternatively be implemented by means of two or more interacting electronic control units of the motor vehicle.

Fig. 3 shows a surface diagram illustrating an embodiment of a method according to the present invention for controlling a flood of gearbox oil of a system 10 of the type described above. In a first step Si, the electronic control device 20 determines whether a shifting process of changing gear in the gearbox 1 has been initiated. If the electronic control device 20 in step Si has determined that no shifting process has been initiated, this step Si is repeated after a certain time delay. If the electronic control device 20 in step S1 determines that a shifting process has been initiated, the electronic control device 20 calculates in a subsequent second step S2 a drilling value N 1 /, for an increased speed of the electric motor 19. In a third step S3 the electric motor is controlled 19 of the electronic control device 20 to assume a speed corresponding to said drill value N. /, so that the speed of the electric motor 19 decreases from a normal speed level 6 to an increased speed level. In a fourth step S4, the electronic control device 20 determines whether the shifting process has been completed. If the electronic control device 20 in step S4 has determined that the switching process has not been completed, this step S4 is repeated after a certain time delay. If the electronic control device 20 in step S4 determines that the shifting process has been completed, the electronic control device 20 in a subsequent fifth step S5 controls the speed of the electric motor to be reduced from the increased speed level to the normal speed level. Then the above-mentioned first step Si is repeated.

Computer program code for implementing a method according to the invention is suitably included in a computer program which can be loaded into the internal memory of a computer, such as the internal memory of an electronic control unit of a motor vehicle. Such a computer program is suitably provided via a computer program product, including a computer storage medium which can be read by a computer, which data storage medium has been stored by the computer program. Said data storage medium is, for example, an optical data storage medium in the form of a CD-ROM, a DVD disc, etc., a magnetic data storage medium in the form of a hard disk, a floppy disk, a cassette tape, etc., or a flash memory or a ROM type memory. PROM, EPROM or EEPROM.

Fig. 2 very schematically illustrates an electronic control unit comprising an execution means 31, such as a central processor unit (CPU), for executing computer software. The execution means 31 communicates with a memory 32, for example of the RAM type, via a data bus 33. The control unit 30 also comprises data storage medium 34, for example in the form of a Flash memory or a memory of the type ROM, PROM, EPROM or EEPROM. The execution means 31 communicates with the data storage medium 34 via the data bus 33. A computer program comprising computer program code for implementing a method according to the invention, for example in accordance with the embodiment illustrated in Fig. 3, is stored on the data storage medium 34.

The system and method according to the invention are particularly intended for use with a heavy motor vehicle, such as, for example, a bus, a towing vehicle or a truck.

The invention is of course not limited in any way to the embodiments described above, but a number of possibilities for modifications thereof should be obvious to a person skilled in the art, without this deviating from the basic idea of the invention as defined in the appended claims. 13

Claims (15)

PATENT REQUIREMENTS A system for lubricating and cooling a gearbox (1) provided with synchronizing couplings (2, 2 ', 2 "), which system (10) comprises: - an oil line (11) connected to oil channels (12) in gearbox to allow gear oil to be supplied from the oil line (11) to said oil channels (12) for lubrication and cooling of bearings and synchronizing couplings (2, 2 ', 2 ") inside the gearbox (1), - an oil pump (13) for generating a flood of gear oil through the oil line (11) in the direction of said oil channels (12), and - a cooling device (14) connected to the oil line (11) for cooling the gear oil, characterized in that: - that the system (10) comprises an electric motor ( 19) for driving the oil pump (13), and an electronic control device (20) for controlling the speed of the electric motor (19), and - that the electronic control device (20), when it receives information indicating that a shifting process for replacement of gear in the gearbox (1) has been initiated e is intended to be initiated, is arranged to control the speed of the electric motor to temporarily increase from a normal speed level to an increased speed level in order to thereby produce a temporary increased volume flow of gear oil in the oil line (11) and in said oil channels (12) below the changeover process and thereby a temporarily increased cooling effect of the gearbox oil flowing through the oil channels (12). 14 2. A system according to claim 1, characterized in that the electronic control device (20) is arranged to control the electric motor (19) to assume a speed corresponding to a predetermined fixed drill value during said temporary speed increase. A system according to claim 2, characterized in that said fixed drilling value corresponds to a maximum permitted speed of the electric motor (19). A system according to claim 1, characterized in that: - that the electronic control device (20) is arranged to calculate a drill value (Nca / c) for the temporary increased speed of the electric motor based on a predetermined calculation model, and - that the electronic control device (20 ) is arranged to control the electric motor (19) at said temporary increase in speed to assume a speed corresponding to said calculated bar value (N./c). A system according to any one of claims 1-4, characterized in that the electronic control device (20) is arranged to control the speed of the electric motor to be reduced from the increased speed level to the normal speed level when the electronic control device (20) determines that a given time elapsed since the time cla the electronic control device (20) initiated said temporary speed increase. System according to any one of claims 1-4, characterized in that the electronic control device (20) is arranged to control the speed of the electric motor to be reduced from the elevated speed level to the normal speed level when the electronic control device (20) has determined that the shifting process has end-cont. Method for controlling a flood of gearbox oil of a system (10) for lubricating and cooling a gearbox (1) provided with synchronizing couplings (2, 2 ', 2 "), the system 10. comprising: - an oil line (11 ) which are connected to oil channels (12) in the gearbox may allow gear oil to be fed from the oil line 11. to said oil channels (12) for lubrication and cooling of bearings and synchronizing couplings (2, 2 ', 2 ") inside the gearbox (1 ), - an oil pump (13) for generating a flood of alternating oil through the oil line (11) in the direction of said oil channels (12), and - a cooling device (14) connected to the oil line (11) for cooling the alternating oil, the method being characterized in that: - that the oil pump (13) is driven by an electric motor (19), the speed of which is controlled by an electronic control device (20), and - that the electronic control device (20), when it receives information indicating that a shifting process for replacement of gear in the gearbox (1) has in initiated or is intended to be initiated, the speed of the electric motor controls to temporarily increase from a normal speed level to an increased speed level so as to provide a temporary increased volume flow of gear oil in the oil line (11) and in the said oil ducts (12) during the gear cycle. and thereby a temporarily increased cooling effect of the gearbox oil flowing through the oil channels (12). Method according to claim 7, characterized in that the electronic control device (20) during said temporary speed increase controls the electric motor (19) to assume a speed corresponding to a predetermined fixed drill value. A method according to claim 8, characterized in that said fixed drill value corresponds to a maximum to Met speed for the electric motor (19). Method according to claim 7, characterized in that: - that the electronic control device (20) calculates a bar value (Nca / c) for the temporary increased speed of the electric motor based on a predetermined calculation model, and - that the electronic control device (20) during said temporary speed increase, the electric motor (19) controls to assume a speed corresponding to said calculated drill value (AT calc) • A method according to any one of claims 7-10, characterized in that the electronic control device (20) controls the speed of the electric motor to be reduced from the elevated speed level to the normal speed level when the electronic control device (20) determines that a given time has elapsed since the time when the electronic control device (20) initiated said temporary speed increase. 17 A method according to any one of claims 7-10, characterized in that the electronic control device (20) controls the speed of the electric motor to be reduced from the increased speed level to the normal speed level when the electronic control device (20) has determined that the shifting process has been completed. A computer program comprising computer program code may cause a computer to implement a method according to any of claims 7-12 when the computer program is executed on the computer. A computer program product comprising a computer storage medium readable by a computer, the computer program code of a computer program according to claim 13 being stored on the data storage medium. An electronic control unit of a motor vehicle comprising an execution means (31), a memory (32) connected to the execution means and a data storage medium (34) connected to the execution means, the computer program code of a computer program according to claim 13 being stored on said data storage medium (34). 18 liz CO o2 / 2,