SEMIAUTOMATIC TRANSMISSION

Abstract: Semiautomatic transmission for vehicles, construction machines or similar equipment, in one embodiment of the invention the semiautomatic transmission comprises a synchro-mesh transmission (16), which has an electrically controlled gear shift mechanism (4), an electric control unit (2) for controlling the gear shift mechanism (4), and sensors (12, 20a and 20b) for measuring the torque of the engine (10), the rotating speed of the output shaft (18a) of the transmission and the driving speed. The sensors (12, 20a, 20b) are arranged to transmit signals corresponding to measured quantities to the electric control unit (2) for selecting a gear suiting the actual driving situation. Between the output shaft (18a) of the transmission and the drive shaft (18b), with which the power is transmitted to the drive gear (22), there is, in accordance with the invention, a bidirectionally engaging overrunning clutch (21) to connect said shafts (18a, 18b) with each other. The engaging circuit of the transmission is an electric power circuit that is opened and closed by means of the accelerator pedal (11) of the engine (10) or with a similar power regulator.

Description: Saniaiitαnatic transmission The present invention relates to a semiautcmatic -transmission for vehicles, construction inac-hines and similar, which semiautomatic transmission cαπprises a syrκ_hro-_nesh transmission, -which has an electrically controlled gear shift meci-_-nism, a sensor for measuring the engine torque, and sensors for measuring the rotating speeds of drive line shafts located immediately before the transmission or after the transmission, -which sensors transmit signals corres¬ ponding to measured quantities to the electric control unit for selecting a gear suiting the actual driving situation. Semiautcmatic transmissions are kncwn in the prior art, and they are widely used in the drive line systems of motor vehicles and similar equipment. Conventional semiautomatic transmissions are arranged in such a way that the clutch and the t_rar___-_issi<_a are specially designed in order to make the dutch pedal or similar unnecessary. On the other hand, these systems have a normal gear shift selector for selecting the desired driving gear. In these systems the clutch and the -transmission must be specially designed, and the clutch is usually a kind of centrifugal clutch by which the engagement of the drive line depends on the engine speed of revolutions. Usually there is also a torque converter between the clutcih and the transmission for evening up the jerks due to the engagement of the gear thus protecting the transmission. From the point of view of the driver, a conventional system such as this, when installed for instance in a vehicle, differs fr n a usual manual transmission only in that the clutch pedal has been emitted or that it is not necessary to use the clutch pedal when shifting the gear. Therefore it is the driver of the vehicle who always selects the desired driving gear. Thus the driver must concentrate on the selection of the gear and distract his attention from the actual driving. The object of the present invention is to provide a new type of semiautcmatic transmission, which eliminates the drawbacks prevalent in the solutions of the prior art. A characteristic feature of the iπventicn is that the transmission is connected with the rest of the drive line with an σveirrunning clutch and that the engaging circuit of the transmission is an electric pcwer circuit that is opened and closed by means of the accelerator pedal of the engine or with a similar pcwer regulator. According to one embodiment of the invention the overt-unning clutch may engage in both rotating directions (a bidirectionally engaging oven_unnirig clutch), and it is installed between the output shaft of the tran__mission and the drive shaft, with which the power is transmitted to the driver gear, in order to connect these shafts together, and that said sensors measuring the rotating speeds are installed an the cutput shaft of the transmission and on the drive shaft for measuring their rotating speeds. An essential feature of this embodiment is that the electric power circuit of the transmission is arranged to be closed when the rotating speeds of the output shaft of the transmission and the drive shaft differ, in other words when the accelerator pedal is lifted up and the engine pcwer has been essentially reduced, or when the speed of the vehicle, i.e. the rotating speed of the drive shaft is zero, and that at other times said electric pcwer circuit is arranged to be open. According to another embodiment of the invention, the σve_-χu-_ning clutch is installed between the clutch shaft and the input shaft of the transmission to connect said shafts with each other, and that sεdd sensors measuring the rotating speeds are installed onto the clutch shaft and the input shaft of the transmission to measure the rotating speeds of these shafts. It is characteristic to this second e__bod__t_errt of the invention that the electric pcwer circuit of the transmission is arranged to be closed when the rotating speeds of the clutch shaft and the input shaft of the transmission differ, in other words when the accelerator pedal is lifted up and the engine pcwer has been essen¬ tially reduced, or when the speed of the vehicle, i.e. the rotating speed of the drive shaft is zero, and that at other time said electric pcwer circuit is arranged to be open. Several advantages are attained with the invention when compared with the transmission of the prior art. When using a transmission in accordance with the invention, the vehicle is always driven in the optimum gear. Driving at too lew or too high revs will be avoided which reduces the wear of the engine and the fuel con¬ sumption. The driver of the vehicle may better concentrate en observing the traffic, as he need not "think" about shifting gears, and he need not loosen his hold of the steering wheel. A semi- automatic transmission in accordance with the invention can easily be applied both to front wheel drive and rear vftieel drive vehicles, as the oven_unning clutch can be installed onto the clutch shaft or onto the drive shaft after tiransmission. The σveixunning clutch may in one embodiment of the invention be a conventional unidirec- tiαnally engaging ovei-j-unning clutch if the ove_ .unning clutch is installed onto the clutch shaft, because, as we knew, the clutch shaft rotates to one direction only. However, in order to provide the possibility of engine braking, a unidi-rectiαnal clutch must have a locking feature. The σvennjnning clutch can also be a bi- directionally engaging σve_-__unning clutch for providing engine braking without a separate locking device. The invention will new be described by the help of an example with reference to the figures in the accompanying drawing, which sche- matically illustrate a drive-line system of a vehicle or similar, in whic a semiautomatic transmission in accordance with the in¬ vention is used. Fig. 1 illustrates the first ernbodiment of the invention. Fig. 2 illustrates the second erabodiment of the invention. Fig. 1 of the drawing schematically illustrates a drive-line system which comprises a motor 10, a clutch 14, a transmission 16, a two- section drive shaft coming out of the transmission comprising an output shaft lδa of the transmission 16 and a drive shaft lδb, an oveπ-urming clutch 21, and a drive gear 22. The σvenπaning clutch 21 is bidirectionally engaging, and it is installed between the output shaft 18a of the transmission 16 and drive shaft 18b to connect said shafts 18a and lδb to each other. The clutch 14 is a conventional clutc vised in association with manual t_ransmissions, and transmission 16 is quite a normal syrκ_hro-mesh transmission. The only difference of the transmission 16 from conventional trans¬ missions is in its shifting mechanism. In a transmission in accord¬ ance with the invention, the shifting mechanism 4 is electric or electrically controlled, and the gear shifting elements may be solenoids, linear motors, electrically controlled hydraulic or pneumatic valves or similar. The pcwer of the engine 10 is regulated in the normal way with a pcwer regulator such as a so called accelerator pedal 11 or similar, and the engine 10 is also equipped with a sensor 12 that measures the Bcanentary torque of the engine. In association with the output shaft lδa of the txansmissiαn 16 there is one sensor 20a, which measures the rotating speed of said output shaft lδa, and in associ¬ ation with the drive shaft lδb there is another sensor 20b, which measures the rotating speed of the drive shaft 18b. The sensor 20b may of course be installed in another suitable place after the output shaft lδa of the transmission 16 and the cverrrt-nning clutch 21, vfaere it measures a quantity that is directly μtxportiαnal to the driving speed of the vehicle. As was said above, the clutch 14 s gμite a normal clutch used in the drive line of a motor vehicle and manoeuvred with a clutch pedal 6 or similar. For engaging gears the transmission is equipped with an electric engaging circuit v_hose design will be described belcw. In associ- atiαn with the electric engaging circuit there is an electric control unit 2, which, in the embodiment illustrated in Fig. 1, receives the torque information frcm the sensor 12 and signals coming frcm the sensors 20a and 20b carrying information about the rotating speeds of the output shaft lδa of the tiransmission 16 and the drive shaft iδb. The control unit 2 has a memory for storing necessary set values for the engine torque and the rotation speed of the drive shaft or the driving speed of the vehicle for each gear. The set values are not exact values of the torque and speed but ranges on which the vehicle may operate in different gears. The control unit 2 compares the signals received frcm sensors 12, 20a and 20b with the set values stored in the memory and transmits a necessary pulse to the shifting inechanism 4 of the transmission 16 for selecting the gear that best suits the current driving situation. The engaging circuit also comprises a control unit δ with necessary switches such as keys 9 for manual selection of the driving direc¬ tion (forward 1, reverse R) and the neutral position V. The keyboard control unit δ transmits the manually issued __nstructiαns into the electric control unit 2, which transmits pulses in accordance with these i_nstructiαns to the shifting inechanism 4 of the -transmission 16. The keyboard control unit 8 also has a switch (key 0) with which it is possible to shift down for instance for fast acceler¬ ation. Pushing dcwn key 0 makes the system by-pass the control pulse generated by the electric control unit 2. A pcwer source 7 is of course connected to the engaging circuit for providing the necessary electric pcwer for ti-ansπ tting the pulses. The special feature of the electric engaging circuit is that in the normal situation the electric pcwer circuit of the engaging circuit is cpen, which means that the shifting inechanism 4 of the transmission 16 cannot engage a new gear. The engaging circuit is turned on vΛien one of the sensors 20b reports that the speed of the vehicle is zero or when both sensors 20a and 20b report that the rotating speeds of the output shaft i8a of the t-remsmissicn 16 and the drive shaft lδb differ. The rotating speeds of the shafts lδa and lδb are different when the drive line is out of gear, i.e. when the accelerator pedal is lifted up. When the accelerator pedal 11 is lifted up, the over¬ running clutch 21 disengages the cutput shaft lδa of the trans¬ mission 16 from the drive shaft lδb. New the electric pcwer circuit of the engaging circuit is closed and the shifting mechanism of the transmission engages a new gear. Therefore, regardless of the driving situation, the driver himself always selects the driving gear by using the accelerator pedal 11. r jhe drive line system illustrated in Fig. 2 of the drawing is mostly analogous to the one illustrated in Fig. 1, and the same cc-πpαneπts are referred to by same item numbers. In Fig. 2, the system comprises the engine 10, the clutch 14, a two-section drive shaft between the clutch 14 and the transmission 16 comprising a clutch shaft 25a and an input shaft 25b of the transmission 16, an ove__rttnning clutch 27, the transmission 16, a drive shaft 28 and the drive gear 22. As distinct frcm the embodiment of Fig. 1, the σve]__n_nn__ng clutch may be either of the conventional x_nidireσtional type or bidirectional (engaging to both rotating directions), and it is installed between the clutch shaft 25a and the input shaft 25b of the transmission 16 to connect said shafts 25a and 25b with each other. If the σve_ * τur_ni_ng clutch 27 is unidirectional (engages in one direction only), it must, in order to provide the possibility of engine braking, have a locking feature. Even in -this embodiment the clutch 14 is a conventional clutch in association with manual transmissions, and the transmission 16 is quite a normal synchro- mesh transmission. The shifting mechanism 4 of the transmission 16 is similar to one illustrated in Fig. 1; also the gear shifting elements are analogous. m the same way as described in the context of Fig. 1, the engine pwer is regulated with a pcwer regulator such as a so called accelerator pedal 11 or similar, and the engine 10 is also equipped with a sensor 12 that measures the mementary torque of the engine. The arrangerneπt of components differs from the embodiment of Fig. 1 in the following way. In association with the clutch shaft 25a there is a third sensor 26a for measuring the rotating speed of said clutch shaft 25a, and in association with the input shaft 25b of the tetnsmissiαn 16 there is a fourth sensor 26b for measuring the rotating speed of the input shaft 25b of the transmission 16. There can be a fifth sensor 30 on the drive shaft 2δ or in another suitable place for measuring a quantity that is directly pro¬ portional to the driving speed of the vehicle. In Fig. 2 the sensor 30 is indicated with dotted lines. As was said above, the clutch 14 is quite a normal clutch used in the drive line of a motor vehicle and manoeuvred with a clutch pedal 6 or similar. In the embodiment of Fig. 2, the design of the electric engaging circuit is as follcws. In association with the electric engaging circuit there is an electric control unit 2, which receives the torque information frcm the sensor 12 and signals co ing from the sensors 26a and 26b carrying information abcut the rotating speeds of the drive shaft 25a and the input shaft 25b of the transmission 16 and from the possible sensor 30 measuring the rotating speed of the drive shaft 28. The control unit 2 has a similar memory as in Fig. 1 for storing set values in a way analogous with Fig. 1. The control unit 2 compares the signals received frcm sensors 12,26a and 26b and 30 with the set values stored in the memory and trans- mits a necessary pulse to the shifting mec___u * _ism 4 of the trans¬ mission 16 for selecting the gear that best suits the current driving situation. The engaging circuit also comprises a control unit δ whose design and function are described in the context of Fig. 1. In the em¬ bodiment of Fig. 2, the engaging circuit is turned on when the fourth sensor 26b and the fifth sensor 30 report that the speed of the vehicle is zero or tdien the third and the fcurth sensors 26a and 26b report that the rotating speeds of the clutch shaft 25a and the input shaft 25b of the tr_-nsmissiαn 16 differ. The rotating speeds of shafts 25a and 25b are different when the drive line is δ out of gear, i.e. when the accelerator pedal is lifted up. When the accelerator pedal 11 is lifted up, the cveirrunning clutch 27 disengages the clutch shaft 25a frcm the input shaft 25b of the transmission 16. New the electric pcwer circuit of the engaging circuit is closed and the shifting icechanism of the transmission engages a new gear. Therefore, also in the case of Fig. 2, the driver himself always selects the driving gear by using the accel¬ erator pedal 11, regardless of the driving situation. The follcwing is a more detailed description of hew a semiautomatic transmission in accordance with the invention works. When starting out a journey, the first thing is, as usually, to turn on the pcwer. When this is done, the keyboard control unit 8 and the electric control unit 2 gets a signal carrying the message that the driving speed is zero. In the et-bcx≤Limeπt of Fig. 1, this signal is transmitted by the rotating speed sensor 20b, in the embodiment of Fig. 2, this signal comes frcm the fourth rotation speed sensor 26b and or the fifth rotation speed sensor 30. This will close the current circuit, and the function pulse transmitted by the electric control unit 2 goes to the shifting inechanism 4 of the -transmission 16 which disengages the gear if the t__ansmission has been left in gear (and not in neutral) after last driving. Now the engine 10 can be started. When beginning to back up the vehicle, the clutch pedal 6 is pressed down in the normal way which disengages the engine 10 from the drive line. The clutch 6 need to be operated only vΛien starting off and stopping, as the σverninning clutch 21 or 27 takes care of the other disengagements of the drive line. After disengaging the engine 10, the driver pushes the key R of the keyboard 9 of the control unit 2. An instruction issued by the key R by-passes the electric control unit 2 and proceeds to the shifting mechanism 4 of the transmission 16 which shifts the transmission to reverse. New the clutch pedal 6 is lifted up in the normal way and the backing up may start. The backing up is interrupted by pressing down the clutch pedal. When the speed of the vehicle is zero, the electric control unit 2 shifts the transmission to neutral by means of the shifting inechanism 4 of the transmission 16. When beginning to drive forwards the procedure is the same as above except that new the driver pushes the key 1 of the keyboard 9 of the control unit 2. If the driving is interrupted by pressing the clutch pedal 6 down and braking the speed of the vehicle to zero, the electric control unit 2 shifts the transmission to neu¬ tral. In the embodiment of Fig. 1, if the speed is increased, the electric control unit selects frcm the shift mechanism 4 of the transmission 16, by signals ccming frcm one rotation speed sensor 20b and the torque sensor 12 and by the information stored in the rotation speed memory, a gear shifting element matching the actual driving speed ready to operate. In the embodiment of Fig. 2, if the speed is increased, the electric control unit selects from the shift mechanism 4 of the transmission 16, by signals ccming from the fourth rotation speed sensor 26b and/or the fifth sensor 30 and the torque sensor 12 and by the information stored in the rotation speed memory, a gear -shifting element matching the actual driving speed ready to operate. In the embodimei-t of Fig. 1, when the accelerator pedal 11 is new lifted, the overrunning clutch disengages the output shaft lδa of the transmission 16 frcm the drive shaft lδb. This results in a speed difference between said shafts lδa and 18b, which is recorded by the control unit 2 by signals arriving from the sensors 20a and 20b. Said difference in the rotating speeds closes the current circuit which makes the gear shifting element engage the right gear. When the vehicle is being driven, the rotation speed sensor 20a continuously measures the rotating speed of the drive shaft lδb and the -torque sensor 12 contiπucusly measures the engine torque, and these sensors transmit appropriate signals to the electric control unit 2 and the keyboard control unit δ. m association with the keyboard control unit β there can favcurably be an alarm such as an alarm lamp shewing when the gear should be shifted. This alarm lamp does not necessarily need to shew which gear is needed; it is enough to shew that a wrong gear is on with respect to the driving speed. The situation is corrected by lifting up the accelerator pedal 11, whereat the right gear is __mmediately engaged. When desired, the electric control unit 2 may be by-passed by means of the key 0 of the keyboard control unit δ, whic makes a so-called overtaking gear be engaged. Pushing the 0-key and lifting the accelerator 11 up will shift one gear down, which is often necessary for instance in overtaking situations. Similarly the vehicle can be made coast by shifting to neutral by pushing the key V. In the embodiment of Fig. 2, if the accelerator pedal is lifted in a similar situation, the cverrunning clutch will disengage the clutch shaft 25a frcm the input shaft 25b of the transmission 16. This results in a rotation speed difference between shafts 25a and 25b, which is recorded by the control unit by means of signals arriving frcm the third and the fourth sensors 26a and 26b. This difference in rotation speeds closes the electric circuit vftiereat the correct gear is engaged. When driving, the fourth rotating speed sensor 26b continuously measures the rotating speed of the input shaft 25b of the transmission 16, which speed is, in the ratio determined by the reduction ratio of the tran__missiαn, di¬ rectly prcportioneϋ. to the driving speed, and/or the fifth rotation speed sensor 30 continuously measures the rotating speed of the drive shaft vftiich is also directly proportional to the driving speed, and the torque sensor 12 measures the engine torsion and t-ransmits appropriate signals to the electric control unit 2 and the keyboard control unit δ. In the embodiment of Fig. 2, too, there can favcurably be an alarm device equivalent to the alarm device of the erobodiment of Fig. 1. A .system in accordance with the invention can be used in all " types of vehicles and construction machines. In heavy equipment such as trucks several alternative rotating speed and torque ranges for the same gear should be stored in the memory of the electric control unit 2. Then the range can be .selected according to for instance load, terrain and other conditions. A system in accordance with the invention may be installed afterwards in ∞rrventional manual transmissions. m order to change a conventional manual transmission to a semi¬ autcmatic transmission in accordance with the ecibodiment of Fig. 1, the follcwing must be performed: The engine 10 must be fitted with a torque sensor, and rotating speed sensors must be fitted in association with the output shaft of the transmission and the drive shaft. The output shaft of the transmission and the drive shaft must be connected to each other by means of a bidirectionally engaging σverrui-ning clutch. In order to change the transmission to a semiautcmatic transmission in accordance with the embodiment of Fig. 2, the follcwing must be performed: The engine 10 must be equipped with a torque sensor, and rotating speed sensors must be fitted in association with the clutch shaft 25a, the input shaft 25b of the transmission 16 and the drive shaft 2δ. The clutch shaft and the input shaft of the transmission must be connected to each other with an overrunning clutch. In addition to this, an electric control unit 2 and a keyboard control unit δ will be installed and connected to said sensors in accordance with the invention. The normal mechanical shifting mechanism will be removed and replaced with an electrically con¬ trolled shifting mes-hanism in accordance with the invention. No other changes need be made to conventional transmissions. In a system in accordance with the invention the selection of gears is automated, but the actual shifting is made by the driver by means of the accelerator pedal. The invention is by no means restricted to ernbodijneπts as per the favourable examples described above and illustrated in the figures of the drawing; it may be varied within the framework of the in- veπtiαnal idea as defined in the accctπpanying claims.

Claims: Claims 1. A ses autcmatic transmission for vehicles, construction machines and similar, which serπiaiitcmatic transmission comprises a synchro- mesh transmission (16), which has an electrically cxartrolled gear shift mechanism (4), an electric control unit (2) for controlling the gear shift mechanism (4), a sensor (12) for measuring the torque of the engine (10), and sensors (20a,20b or 26a,26b) for measuring the rotating speeds of the drive line shafts (lδa,lδb or 25a,25b) located immediately before the transmission or after the transmission, whic sensors transmit signals corresponding to measured quantities to the electric control unit (2) for selecting a gear suiting the actual driving situation, wherein the trans¬ mission is connected with the rest of the drive line with an over- running clutch (21;27) and that the engaging circuit of the trans¬ mission is an electric pcwer circuit that is opened and closed by means of the accelerator pedal (11) of the engine (10) or with a similar pcwer regulator. 2. A semiautomatic transmission in accordance with claim 1, wherein the overrunning clutch (21) may engage in both rotating directions (a bidirectionally engaging σve_ * τunning clutch) , and is installed between the output shaft (lδa) of the transmission (16) and the drive shaft (lδb), with which the pcwer is transmitted to the driver gear (22), in order to connect these shafts (lδa,lδb) to¬ gether, and that said sensors (20a,20b) measuring the rotating speeds are installed on the output shaft (lδa) of the transmission (16) and on the drive shaft (18b) for measuring the rotating speeds of these shafts (lδa,lδb) . 3. A semiautcmatic transmission in accordance with claims 1 and 2, wherein the electric pcwer circuit of the transmission is arranged to be closed when the rotating speeds of the output shaft(18a) of the transmission and the drive shaft (lδb) differ, in other words wh n the accelerator pedal (11) is lifted up and the pcwer of the engine (10) has been essentially reduced, or when the speed of the vehicle, i.e. the rotating speed of the drive shaft (lδb) is zero, and that at other times said electric pcwer circuit is arranged to be open. 4. A semiautomatic transmission in accordance with claim 1, wherein the overrunning clutch (27) is installed between the clutch shaft (25a) and the input shaft (25b) of the transmission (16) to connect said shafts (25a and 25b) with each other, and that said sensors (26a,26b) measuring the rotating speeds are installed onto the clutch shaft (25a,25b) and the input shaft (25b) of the transmission (16) to measure the rotating speeds of these shafts. 5. A semiautcmatic transmission in accordance with claims l and 4, wherein said σveixunning clutch (27) is bidirectionally engaging in order to provide an engine braking feature. 6. A semiautcmatic transmission in accordance with claims 1 and 4, wherein said σve__ru_-_ιing clutch (27) has a locking device in order to provide an engine braking feature. 7. A semiautcmatic tø_r___mission in accordance with one of claims 1 and 4 to 6, wherein a sensor (30) is installed in association with the engaging circuit onto the drive shaft (2δ) between the trans¬ mission (16) and the drive gear (22) for measuring the driving speed and for transmitting a signal corresponding to the driving speed to said electric control unit (2) . δ. A semiautcmatic transmission in accordance with one of claims 1 and 4 to 7, wherein the electric pcwer circuit of the transmission is arranged to be closed vήien the rotating speeds of the clutch shaft (25a) and the input shaft (25b) of the transmission differ, in other words when the accelerator pedal (11) is lifted up and the pcwer of the engine (19) has been essentially reduced, or vftien the speed of the vehicle, i.e. the rotating speed of the drive shaft (2δ) is zero, and that at other times said electric pcwer circuit is arranged to be open. 9. A semiautcmatic -transmission in accordance with one of claims 1 to 3 or 1 and 4 to δ, wherein the electric control unit (2) is arranged to carry out the selection of gears by comparing the set values of the driving speed and the engine torque stored in its memory to mcmentary values transmitted by said sensors (12,20a and 20b;26a and 26b) and by selecting frcm the .shifting mechanism (4) of the transmission (16) a gear matching the driving speed, whic gear will be shifted on when the accelerator pedal (11) is lifted up thus essentially reducing the power of the engine (10). 10. A semiautcmatic transmission in accordance with one of claims 1 to 9, wherein there is a control unit (δ) in association with the engaging circuit, which has keys (9) or similar switches, with which the driver, when starting the vehicle, can manually select the driving direction, and with which he can by-pass the electric control unit (2) in order to shift to neutral and/or to at least one step lower gear. 11. A semiautcmatic transmission in accordance with claim 11, wherein in association with the control unit (δ) there is an alarm device such as an alarm lamp arranged to give an alarm signal when engaged is a gear that does not suit the driving situation.

Inventors: SASSI KARI, TAMMISTO ERKKI, SASSI, KARI, TAMMISTO, ERKKI
Applicants: KONEJUKKA OY
Application year: 1986
Main classification: B60K41
IPC codes: B60W10, B60W30, F16H61