NL2021574B1 - Continuously variable transmission and transmission system - Google Patents

Continuously variable transmission and transmission system Download PDF

Info

Publication number
NL2021574B1
NL2021574B1 NL2021574A NL2021574A NL2021574B1 NL 2021574 B1 NL2021574 B1 NL 2021574B1 NL 2021574 A NL2021574 A NL 2021574A NL 2021574 A NL2021574 A NL 2021574A NL 2021574 B1 NL2021574 B1 NL 2021574B1
Authority
NL
Netherlands
Prior art keywords
pump
gear pump
gear
volume
fluid
Prior art date
Application number
NL2021574A
Other languages
Dutch (nl)
Inventor
Johannes Buijsman Petrus
Original Assignee
Hcvtransmission B V
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 Hcvtransmission B V filed Critical Hcvtransmission B V
Priority to NL2021574A priority Critical patent/NL2021574B1/en
Application granted granted Critical
Publication of NL2021574B1 publication Critical patent/NL2021574B1/en

Links

Abstract

The invention relates to a continuously variable transmission comprising a first gear pump and a second gear pump, wherein the pump volume of the first gear pump and the pump volume of the second gear pump are adjusted in an inverse correlation. to each other. According to a first aspect of the invention, the transmission comprises channels to supply and evacuate fluid to and from cavities between meshing gear teeth. According to a second aspect, the invention provides buffer elements to absorb pressure differences in the respective pump volumes. According to a third. aspect, the invention. provides pressure sensors, a pressurization element and a control unit to control the pressurization element in response to pressure signals from the one or more pressure sensors, in particular to prevent cavitation. According to a fourth aspect, the pump volume of one of the gear pumps may be reduced to zero, to function as a clutch.

Description

Continuously variable transmission and transmission system
BACKGROUND
The invention relates to a continuously variable transmission, in particular for a vehicle, and a transmission system comprising said continuously variable transmission.
Push belts have been widely applied because of their ability to provide a simple yet effective continuously variable transmission. However, push belts are prone to slipping, especially in heavy load applications, e.g. in trucks. Hence, push belt transmissions are only used in relatively light applications.
FR 1.230.990 A discloses a hydraulic variator gear that is operable as a motor. The hydraulic variator gear comprises two rotors which are in mesh with each other between two planes which limit the portion of active teeth. One of the planes is formed at the end of a sleeve which has complimentary inner teeth from those of the rotor, in which the rotor is slidable to increase or decrease the length of the teeth that mesh. A spring is provided to allow for automatic operation of the hydraulic variator gear.
FR 1.230.990 A further discloses the use of two of the variators in an automatic transmission between an engine and a set of wheels of a vehicle. The engine comprises a drive shaft that includes a set of planetary gears. The annulus of said planetary gears is engaged by a first variator that operates as a hydraulic motor. The first variator is hydraulically connected to and drives a second variator that functions as a hydraulic pump. The second variator is mechanically coupled to the drive shaft of the engine to deliver more torque if the resistive torque on the wheels decreases and to deliver more speed if the resistive torque on the wheels increases. The known automatic transmission provides a continuous range of speed and torque which are automatically adapted to difficulties encountered. The second variator can be manually operated to introduce speed ratios or additional torque for exceptional roads, e.g. steep slopes or all terrain.
In said known automatic transmission, only a portion of the power of the engine travels through the variators and is affected by their performance. Moreover, the transmission ratio between the rotational speed of the engine and the rotational speed of the wheels is limited to the gear ratios as defined by the planetary gears. Hence, although the speed and torque may be continuously adjusted, the choice of transmission ratios is limited.
It is an object of the present invention to provide an alternative continuously variable transmission and a transmission system comprising said continuously variable transmission.
SUMMARY OF THE INVENTION
According to a first aspect, the invention provides a continuously variable transmission comprising a first gear pump and a second gear pump, wherein each gear pump comprises a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, wherein each gear pump further comprises a first gear rotatable within the respective pump volume about a first gear axis and a second gear rotatable within the respective pump volume about a second gear axis and meshing with the first gear over an overlap distance in an overlap direction parallel to the first gear axis for displacing fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, wherein the fluid outlet of the first gear pump is arranged in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump is arranged in fluid communication with the fluid inlet of the first gear pump, wherein each gear pump further comprises an adjustment member for adjusting the pump volume of the respective gear pump, wherein the adjustment member of the first gear pump and the adjustment member of the second gear pump are interconnected by a connecting member that is arranged for adjusting the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation to each other, wherein the first gear pump is provided with a supply channel that extends along a path that allows for fluid communication from the respective pump volume to a cavity between the meshing teeth of the gears of the first gear pump when said cavity increases in volume and an evacuation channel that extends along a path that allows for fluid communication from the cavity between the meshing teeth of the gears of the first gear pump to the respective pump volume when said cavity decreases in volume .
By adjusting the pump volumes in an inverse correlation to each other, with the pump volumes being in fluid communication with each other, the transmission ratio between the rotational speed of the first gear pump and the rotational speed of the second gear pump can be effectively adjusted. By using a fluid as the medium to transmit power in a substantially closed hydraulic circuit, slipping can be reduced, prevented or even eliminated. The transmission according to the present invention can thus be used in a particularly effective and/or efficient manner in both light and heavy load applications, e.g. in vehicles such as trucks. The transmission according to the present invention can further be used to optimize a power source, e.g. a combustion engine or an electrical engine, to run at its optimal rotational speed.
As the gears of the first gear pump are rotated a cavity is formed between the meshing teeth of the gears that, at some point during the rotation, is closed off from the pump volume and subsequently decreases in volume and ultimately increases in volume again before opening up to the pump volume. The trapped fluid slows down of even prevents rotation of the gears. The supply channel and the evacuation channel cooperate to prevent that fluid is trapped between the teeth of the gears of the first gear pump.
In an embodiment thereof the second gear pump is provided with a supply channel that extends along a path that allows for fluid communication from the respective pump volume to a cavity between the meshing teeth of the gears of the second gear pump when said cavity increases in volume and an evacuation channel that extends along a path that allows for fluid communication from the cavity between the meshing teeth of the gears of the second gear pump to the respective pump volume when said cavity decreases in volume. Hence, the same technical advantage can be obtained in the second gear pump. According to a second aspect, the invention provides a continuously variable transmission comprising a first gear pump and a second gear pump, wherein each gear pump comprises a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, wherein each gear pump further comprises a first gear rotatable within the respective pump volume about a first gear axis and a second gear rotatable within the respective pump volume about a second gear axis and meshing with the first gear over an overlap distance in an overlap direction parallel to the first gear axis for displacing fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, wherein the fluid outlet of the first gear pump is arranged in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump is arranged in fluid communication with the fluid inlet of the first gear pump, wherein each gear pump further comprises an adjustment member for adjusting the pump volume of the respective gear pump, wherein the adjustment member of the first gear pump and the adjustment member of the second gear pump are interconnected by a connecting member that is arranged for adjusting the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation to each other, wherein the transmission is provided with one or more buffer elements to absorb pressure differences in the respective pump volumes.
The transmission preferably is a closed system. Hence, the buffer elements can absorb small pressure fluctuations in the closed system and prevent that the system malfunctions as a result of said pressure fluctuations. Pressure fluctuations may be caused by temperature variations and/or cavitation.
In an embodiment thereof the one or more buffer elements are formed by small chambers with variable volumes that are in direct communication with the respective pump volumes, wherein the variable volume of the chambers is biased to the smallest volume. The provision of biased variable volumes can be relatively simple, yet effective way of absorbing pressure fluctuations in the pump volumes.
According to a third aspect, the invention provides a continuously variable transmission comprising a first gear pump and a second gear pump, wherein each gear pump comprises a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, wherein each gear pump further comprises a first gear rotatable within the respective pump volume about a first gear axis and a second gear rotatable within the respective pump volume about a second gear axis and meshing with the first gear over an overlap distance in an overlap direction parallel to the first gear axis for displacing fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, wherein the fluid outlet of the first gear pump is arranged in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump is arranged in fluid communication with the fluid inlet of the first gear pump, wherein each gear pump further comprises an adjustment member for adjusting the pump volume of the respective gear pump, wherein the adjustment member of the first gear pump and the adjustment member of the second gear pump are interconnected by a connecting member that is arranged for adjusting the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation to each other, wherein the transmission is provided with one or more pressure sensors to detect the pressure in the respective pump volumes, a pressurization element to adjust the pressure in the respective pump volumes and a control unit that is operationally connected to the one or more pressure sensors and the pressurization element to control the pressurization element in response to pressure signals from the one or more pressure sensors.
The previously mentioned buffer elements were passive elements. In contrast, the pressurization element can be actively controlled by the control unit based on the measurement signals of the pressure sensors. Consequently, the transmission is able to react more accurately to pressure changes and possibly predict and/or act proactively to prevent pressure differences.
In an embodiment thereof the control unit is arranged for controlling the pressurization element to increase the pressure in the gear pumps to a level that reduces cavitation. At some point, the gear pumps may run so fast that the fluid used in the continuously variable transmission is unable to flow through the teeth of the gears fast enough. This can cause cavitation. When fluid starts to cavitate, thermal energy is released and the temperature of the fluid will locally rise. The temperature can reach the boiling point of the fluid. When the fluid cools down, implosions can occur that can damage the transmission, even the hard-metal parts thereof. By increasing the pressure, the fluid is forced through the gear pumps more consistently and the risk of cavitation can be reduced.
According to a fourth aspect, the invention provides a continuously variable transmission comprising a first gear pump and a second gear pump, wherein each gear pump comprises a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, wherein each gear pump further comprises a first gear rotatable within the respective pump volume about a first gear axis and a second gear rotatable within the respective pump volume about a second gear axis and meshing with the first gear over an overlap distance in an overlap direction parallel to the first gear axis for displacing fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, wherein the fluid outlet of the first gear pump is arranged in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump is arranged in fluid communication with the fluid inlet of the first gear pump, wherein each gear pump further comprises an adjustment member for adjusting the pump volume of the respective gear pump, wherein the adjustment member of the first gear pump and the adjustment member of the second gear pump are interconnected by a connecting member that is arranged for adjusting the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation to each other, wherein the pump volume
of one of the gear ; pumps is reducable to zero .
In this manner, the continuously variable
transmission can effectively be used as a
coupling/decoupling between an engine and wheels, thus eliminating the need for a conventional, separate clutch.
In an embodiment thereof the transmission further comprises a bypass channel that is arranged to bypass the pump volume of said one gear pump when its pump volume is reduced to zero. The bypass channel ensures that the other gear pump can keep running. Hence, the other gear pump can be coupled to a running engine that can keep running while the transmission functions as a clutch.
The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications .
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be elucidated on the basis of an exemplary embodiment shown in the attached schematic drawings, in which:
figure 1 shows an isometric view of a continuously variable transmission according to a first embodiment of the invention;
figure 2 shows an exploded view of the continuously variable transmission according to figure 1;
figure 3 shows an isometric view of the continuously variable transmission of figure 1 without its housing;
figure 4 shows a partial cross section of the continuously variable transmission according to line IV-IV in figure 1, with the transmission in a first transmission position;
figure 5 shows the partial cross section of the transmission according to figure 4, with the continuously variable transmission in a second transmission position;
figures 6 and show cross sections of the continuously variable transmission according to line VI-VI in figure 4 and line VII-VII in figure 5, respectively;
figure 8 shows a cross section of the continuously variable transmission according to line VIIIVIII in figure 1;
figures 9 and 10 show a cross section of an alternative continuously variable transmission according to a second embodiment of the invention;
figure 11 shows a cross section of a further alternative continuously variable transmission according to a third embodiment of the invention; and figure 12 shows a cross section of a further alternative continuously variable transmission according to a fourth embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Figures 1-8 show a continuously variable transmission 1 according to a first exemplary embodiment of the invention. Said transmission 1 can be used as a continuously variable transmission in a transmission system for a vehicle, for an elevator, for a hoisting crane or for another transmission purpose.
As shown in figures 1-7, said continuously variable transmission 1 comprises a first gear pump 2 and a second gear pump 3 which, in this example, are external gear pumps 2, 3. As best seen in figure 2, the first gear pump 2 comprises a first housing part 20 with a fluid inlet 21 and a fluid outlet 22. As shown in figure 8, the first gear pump 2 comprises a pump volume VI extending between the fluid inlet 21 and the fluid outlet 22. The first gear pump 2 further comprises a first gear 23 that is rotatable within the pump volume VI of the first gear pump 2 about a first gear axis Al and a second gear 24 that is rotatable within the pump volume VI of the first gear pump 2 about a second gear axis A2 . The first gear 23 and the second gear 24 are external gears. The second gear axis A2 is parallel to and spaced apart from the first gear axis Al such that the teeth of the second gear 24 engage and/or mesh with the teeth of the first gear 23. As best seen in figures 3-7, the first gear 23 and the second gear 24 are in meshing overlap with each other over an overlap distance XI in an overlap direction Dl parallel to the first gear axis Al . Fluid, e.g. oil or another suitable medium, is displaced through the pump volume VI of the first gear pump 2 from the respective fluid inlet 21 to the respective fluid outlet 22 by the meshing teeth of the first gear 23 and the second gear 24.
As shown in figures 2-7, the first gear pump 2 further comprises a holding member 4 and an adjustment member 5 that together with the first housing part 20 bound and/or define the pump volume VI of the first gear pump 2. In particular, the holding member 4 and the adjustment member 5 define the pump volume VI in a direction parallel to the overlap direction Dl while the first housing part 20 defines the pump volume VI in a circumferential direction about the first gear axis Al and/or the second gear axis A2. The adjustment member 5 is movable in the overlap direction Dl towards and away from the holding member 4 to adjust the pump volume VI of the first gear pump 2.
As best seen in figure 2, the holding member 4 is provided with a base 41 for holding the first gear 23 and a receptacle 42 for at least partially receiving the second gear 24. The base 41 is stationary while the receptacle 42 is rotatable with respect to said base 51 about the second gear axis A2. As shown in figures 3-7, the base 41 and the receptacle 42 form a first surface section 43 and a second surface section 44, respectively. Together, said surface sections 43, 44 form a first sealing surface 45 for sealing the pump volume VI of the first gear pump 2 in the overlap direction Dl at the side of the holding member 4. The second surface section 44 is rotatable with respect to the first surface section 43 about the second gear axis A2 together with the second gear 24 and is provided with an opening 46 with a contour that is a negative of the contour of the second gear 24. Preferably, the tolerance between the opening 46 and the contour of the second gear 24 is so small that it does not allow fluid inside the pump volume VI to escape through said opening 46. Most preferably, the second surface section 44 sealingly abuts the second gear
24. Hence, the second gear 24 can be at least partially received through said opening 46 in the overlap direction DI while the second surface section 44 effectively seals the pump volume VI at said second gear 24.
As best seen in figures 5 and 7, the receptacle 42 of the holding member 4 has a receiving space 47 that has the same shape as the opening 46 in the second surface section 44. More in particular, as shown in figure 2, the receptacle 42 comprises a plurality of fingers 48 defining said receiving space 47 and extending in the overlap direction DI between the teeth of the second gear 24 to seal the intermediate spaces between said teeth. The second surface section 44 is formed at the distal ends of said fingers 4 8.
As best seen in figure 2, the adjustment member 5 comprises a base 51 for holding the second gear 24 and a receptacle 52 for at least partially receiving the first gear 23. The base 51 is stationary while the receptacle 52 is rotatable with respect to said base 51 about the first gear axis Al. As shown in figures 3-7, the base 51 and the receptacle 52 form a first surface section 53 and a second surface section 54, respectively. Together, said surface sections 53, 54 form a second sealing surface 55 for sealing the pump volume VI of the first gear pump 2 in the overlap direction DI at the side of the adjustment member
5. The second surface section 54 is rotatable with respect to the first surface section 53 about the first gear axis Al together with the first gear 23 and is provided with an opening 56 with a contour that is a negative of the contour of the first gear 23. Preferably, the tolerance between the opening 56 and the contour of the first gear 23 is so small that it does not allow fluid inside the pump volume VI to escape through said opening 56. Most preferably, the second surface section 54 sealingly abuts the first gear 23. Hence, the first gear 23 can be at least partially received through said opening 55 in the overlap direction DI while the second surface section 54 effectively seals the pump volume VI at said first gear 23.
As best seen in figures 5 and 7, the receptacle 52 of the adjustment member 5 has a receiving space 57 that has the same shape as the opening 56 in the second surface section 54. More in particular, as shown in figure 2, the receptacle 52 comprises a plurality of fingers 58 defining said receiving space 57 and extending in the overlap direction Dl between the teeth of the first gear 23 to seal the intermediate spaces between said teeth. The second surface section 54 is formed at the distal ends of said fingers 58.
As shown in figures 3-7, the pump volume VI of the first gear pump 2 is defined in the overlap direction Dl between the aforementioned first sealing surface 45 at the holding member 4 and the aforementioned second sealing surface 55 at the adjustment member 5. The adjustment member 5 is movable towards the holding member 4 in the overlap direction Dl, thereby providing a relative movement of the second gear 24 with respect to the first gear 23 in said overlap direction Dl . In particular, the second gear 24 is at least partially moved out of the meshing overlap with the first gear 23, wherein the part of the second gear 24 that is no longer in meshing overlap with the first gear 23 is passed through the opening 46 in the first sealing surface 45. Hence, said part of the second gear 24 is effectively sealed off from the pump volume VI of the first gear pump 2. Similarly, the first gear 23, which is held by the holding member 4, is at least partially received in the opening 56 of the approaching second sealing surface 55. Again, the part of the first gear 23 that is received through said opening 56 is effectively sealed off from the pump volume VI of the first gear pump 2.
As a result of the movement of the adjustment member 5 in the overlap direction DI between the positions as shown in figures 4 and 6, the meshing overlap distance XI between the first gear 23 and the second gear 24 of the first gear pump 2 can be adjusted. In figures 3, 4 and 6, the meshing overlap distance XI in the first gear pump 2 is relatively small. In figures 5 and 7, the meshing overlap distance XI has been increased by a factor of at least four, preferably at least six and most preferably at least seven. In other words, the capacity of the first gear pump 2 has been at least quadrupled.
As best seen in figure 2, the second gear pump 3, like the first gear pump 2, comprises a second housing part 30, a fluid inlet 31 and a fluid outlet 32. As shown in figures 3-7, a pump volume V2 is defined that extends between the fluid inlet 31 and the fluid outlet 32 of figure 2. In this exemplary embodiment, the first housing part 20 and the second housing part 30 are arranged to be mounted together to form a single housing 10 for both gear pumps 2, 3, as for example shown in figure 1. The housing 10 comprises a first duct 11 that connects the fluid outlet 22 of the first gear pump 2 in fluid communication to the fluid inlet 31 of the second gear pump 3 and a second duct 12 that connects the fluid outlet 32 of the second gear pump 3 in fluid communication to the fluid inlet 21 of the first gear pump 2. As such, the ducts 11, 12 of the housing 10 form a closed hydraulic circuit between the two pump volumes VI, V2. Hence, a fluid flow Fl, F2 can be generated through the first gear pump 2 and subsequently through the second gear pump 3, as schematically show in figures 3-5 and 8 .
As shown in figures 2-7, the second gear pump 3 further comprises a first gear 33 and a second gear 34 which are rotatable about a first gear axis Bl and a second gear axis B2, respectively. Like the gears 23, 24 of the first gear pump 2, the teeth of the gears 33, 34 of the second gear pump 3 are meshing over an overlap distance X2 in an overlap direction D2 to displace fluid through the pump volume V2 of the second gear pump 3 from the respective fluid inlet 31 to the respective fluid outlet
32. In this exemplary embodiment, the first gear axis Al of the first gear pump 2 and the second gear axis B2 of the second gear pump 3 are coaxial, collinear or aligned and the second gear axis A2 of the first gear pump 2 and the first gear axis Bl of the second gear pump 3 are coaxial, collinear or aligned.
The second gear pump 3 essentially operates in the same way as the first gear pump 2 and - as such - has substantially the same parts. Said parts will only be briefly introduced hereafter as there operation and interaction is the same as operation and interaction of their counterparts in the first gear pump 2. The second gear pump 3, like the first gear pump 2, is provided with a holding member 6 and an adjustment member 7 that together with the second housing part 30 bound and/or define the pump volume V2 of the second gear pump 3. Also like the first gear pump 2, the adjustment member 7 is movable in the overlap direction D2 of the second gear pump 3 towards and away from the holding member 6 to adjust the pump volume V2 of the second gear pump 3.
As best seen in figures 2-6, the holding member 6 of the second gear pump 3 is provided with a base 61 and a receptacle 62 forming a first surface section 63 and a second surface section 64, respectively. Together, said surface sections 63, 64 form a first sealing surface 65 for sealing the pump volume V2 of the second gear pump 3 in the overlap direction D2 at the side of the holding member 6. The second surface section 64 is rotatable with respect to the first surface section 63 about the second gear axis B2 together with the second gear 34 and is provided with an opening 66 and a receiving space 67 with a contour that is a negative of the contour of the second gear 34.
As best seen in figures 2, 3 and 6, the adjustment member 7 comprises a base 71 and a receptacle 72 forming a first surface section 73 and a second surface section 74, respectively. Together, said surface sections 73, 74 form a second sealing surface 75 for sealing the pump volume V2 of the second gear pump 3 in the overlap direction D2 at the side of the adjustment member 7. The second surface section 74 is rotatable with respect to the first surface section 73 about the first gear axis Bl together with the first gear 33 and is provided with an opening 7 6 and a receiving space 77 with a contour that is a negative of the contour of the first gear 33.
As shown in figure 3-7, the pump volume V2 of the second gear pump 3 is defined in the overlap direction D2 between the aforementioned first sealing surface 65 at the holding member 6 and the aforementioned second sealing surface 75 at the adjustment member 7. The adjustment member 7 is movable towards the holding member 6 in the overlap direction D2. As a result of the movement of the adjustment member 7 in the overlap direction D2, the meshing overlap distance X2 between the first gear 33 and the second gear 34 of the second gear pump 3 can be adjusted. In figures 3, 4 and 6 the meshing overlap distance X2 in the second gear pump 3 is larger than the meshing overlap distance XI of the first gear pump 2. In figures 5 and 7, the meshing overlap distance X2 has been decreased by a factor of at least four, preferably at least six and most preferably at least seven. In other words, the capacity of the second gear pump 3 has been reduced by a factor of at least four.
As shown in figures 3-7, the continuously variable transmission 1 is provided with a connecting member 8 that connects the adjustment member 5 of the first gear pump 2 and the adjustment member 7 of the second gear pump 3 to each other. In this exemplary embodiment, the connecting member 8 is a connecting body 80 that extends between and/or is integral with the adjustment member 5 of the first gear pump 2 and the adjustment member 7 of the second gear pump 3. Hence, any movement of the adjustment member 5 of the first gear pump 2 is directly transmitted onto and/or converted into a movement of the adjustment member 7 of the second gear pump 3. In particular, the connecting member 8 is connected to the respective adjustment members 5, 7 such that the pump volume VI of the first gear pump 2 and the pump volume V2 of the second gear pump 3 are adjusted in an inverse correlation to each other. This means that when the pump volume VI of the first gear pump 2 is decreased, the pump volume V2 of the second gear pump 3 is increased and that when the pump volume VI of the first gear pump 2 is increased, the pump volume V2 of the second gear pump 3 is decreased.
More specifically, in this exemplary embodiment, the inverse correlation is an inverse proportionality, meaning that the movement of the adjustment member 5 of the first gear pump 2 relates to the movement of the adjustment member 7 of the second gear pump 3 in a fixed ratio and/or with a certain coefficient. In this example, the inverse proportionality is such that the ratio between an increase of one of the first pump volume VI and the second pump volume V2 and a decrease of the other of the first pump volume VI and the second pump volume V2 is 1:1 and/or the coefficient of the inverse proportionality is minus one. By having said ratio or said coefficient, the combined capacity of the pump volumes VI, V2 of both the first gear pump 2 and the second gear pump 3 remains constant. Hence, the gear pumps 2, 3 can be operated in a closed hydraulic circuit in which the decrease in volume of one of the two pump volumes VI, V2 is absorbed by an equal increase in
volume of the other of the two pump volumes VI, . V2.
By changing the pump volumes VI, V2 of both gear
pumps 2, 3 in an inverse correlation, one of the two gear
pumps 2, 3 will run faster than the other of the two gear
pumps 2, 3. In particular, in a closed hydraulic system in
which the fluid inlets 21, 31 of each of the gear pumps 2,
is connected in fluid communication to fluid outlet 22, 32 of the other of the gear pumps 2, 3, the volumetric amount of fluid pumped through both gear pumps 2, 3 is the same. Hence, the gear pump 2, 3 with the smallest pump volume VI, V2 will tend to rotate the fastest to maintain the same volumetric flow rate with a reduced capacity. Similarly, the gear pump 2, 3 with the largest pump volume VI, V2 will tend to rotate the slowest to maintain the same volumetric flow rate with an increased capacity. Hence, the transmission ratio, i.e. the ratio between the pump volume VI of the first gear pump 2 and the pump volume V2 of the second gear pump 3 can be changed effectively by simply moving the adjustment members 5, 7 of both gear pumps 2, 3 in the aforementioned inverse correlation to each other.
Preferably, the adjustment members 5, 7 of both gear pumps 2, 3 are movable in the respective overlap directions Dl, D2 to obtain a transmission ratio range of at least 1:4 to 4:1, i.e. one revolution of the first gear pump 2 equates to four revolutions of the second gear pump 3 and vice versa. More preferably the adjustment members 5, 7 of both gear pumps 2, 3 are movable in the respective overlap directions Dl, D2 to obtain a transmission ratio range of at least 1:6 to 6:1 and most preferably at least 1:7 to 7:1. Essentially, any transmission ratio can be obtained in which the volumetric amount of fluid being pumped through the smallest pump volume VI, V2 is still effective and/or efficient in driving the rotation of the respective gear pump 2, 3. It is noted that the adjustment member 5 of the first gear pump 2 and the adjustment member 7 of the second gear pump 3 are steplessly movable in the respective overlap directions Dl, D2. Hence, a continuously and/or steplessly variable transmission 1 can be obtained in which any transmission ratio within the range of the adjustment members 5, 7 can be selected.
As schematically shown in figure 1, the continuously variable transmission further comprises a control member 9 that is operationally coupled to the adjustment member 5 of the first gear pump 2, the adjustment member 7 of the second gear pump 3 or the connecting member 8 in figure 2 to control the adjustment of the pump volumes VI, V2 of the first gear pump 2 and the second gear pump 3. The control member 9 may be mechanical component that is suitable connected to one of the aforementioned parts of the transmission 1 to move in unison with said part. Preferably, the control member 9 is arranged on the outside of the housing 10 for manual operation, e.g. a gear lever or a gear stick that connects to the connecting member 8 through a suitably shaped slot (not shown) in the housing 10.
As shown in figures 1-7, one of the gears 23, 24 of the first gear pump 2 is connectable to or provided with an input axle or input shaft 25 for mechanically inputting a rotary motion into the continuously variable transmission
1. In this exemplary embodiment, the first gear 23 is provided with said input shaft 25. Hence, said first gear 23 can be regarded as the drive gear of the first gear pump
2, while the second gear 24 is can be regarded as the idler gear of the first gear pump 2. As further shown in figures and 4-7, one of the gears 33, 34 of the second gear pump is connectable to or provided with an output axle or output shaft 35 for mechanically outputting a rotary motion out of the continuously variable transmission 1. In this exemplary embodiment, the first gear 33 is provided with said output shaft 35. Hence, said first gear 33 can be regarded as the drive gear of the second gear pump 3, while the second gear 34 can be regarded as the idler gear of the second gear pump 3.
The input shaft 25 can be connected directly or indirectly to a source of energy, preferably a source of mechanical energy, e.g. an output shaft of a vehicle engine (only schematically shown with arrow E in figure 1) . The output shaft 35 can be connected directly or indirectly to parts to be driven, e.g. the wheels of a vehicle (only schematically shown with arrow W in figure 1) . In the example of a vehicle, the transmission 1 according to the invention thus forms a continuously variable mechanicalhydraulic transmission 1 that is arranged for hydraulically converting the mechanical rotation of an engine into a mechanical rotation of the wheels according to a continuously variable transmission ratio.
Figures 9 and 10 show an alternative continuously variable transmission 101 according to a second embodiment of the invention. The alternative continuously variable transmission 101 differs from the previously discussed continuously variable transmission 1 in that it is provided with a supply channel 191 and an evacuation channel 192 that cooperate to prevent that fluid is trapped between the
teeth of the gears 22, 23 of the first gear pump 2. The
same channels 191, 192 may be provided in a similar manner
at the second gear pump 3 .
As the gears 22, 23 of the first gear pump 2 are
rotated in the direction as shown with the arrows in figures 9 and 10, a cavity is formed between the meshing teeth of the gears 22, 23 that, at some point during the rotation, is closed off from the pump volume VI, as shown in figure 9, and subsequently decreases in volume and ultimately increases in volume again, as shown in figure 10, before opening up to the pump volume VI. The trapped fluid slows down of even prevents rotation of the gears 23,
24. The evacuation channel 192 extends along a path that allows for fluid communication from the cavity between the meshing teeth of the gears 22, 23 to the pump volume VI when said cavity decreases in volume, i.e. when the cavity is closing, as shown in figure 9. The supply channel 191 extends along a path that allows for fluid communication from the pump volume VI to a cavity between the meshing teeth of the gears 22, 23 when said cavity increases in volume, i.e. when the cavity is opening up, as shown in figure 10.
Figure 11 shows a further alternative continuously variable transmission 201 according to a third embodiment of the invention. The further alternative continuously variable transmission 201 differs from the previously discussed continuously variable transmissions 1,
101 in that it is provided with one or more buffer elements 291, 292 to absorb pressure differences, in particular as a result of cavitation between the teeth of the gears 23, 24. In this exemplary embodiment, the one or more buffer elements 291, 292 are formed by small chambers with variable volumes that are in direct communication with the volumes VI, V2 of the gear pumps 2, 3, e.g. via the ducts 11, 12. The variable volume of the chambers is biased, e.g. by a spring, to the smallest volume, but may increase when the pressure in the volumes VI, V2 is greater than the bias on the chambers. Hence, the volumes VI, V2 can be slightly expanded into the one or more buffer elements 291, 292 in response to pressure variations.
Figure 12 shows a further alternative continuously variable transmission 301 according to a fourth embodiment of the invention. At some point, the gear pumps 2, 3 may run so fast that the fluid used in the continuously variable transmission 301 is unable to flow through the teeth of the gears 23, 24 fast enough. This can cause cavitation. When fluid starts to cavitate, thermal energy is released and the temperature of the fluid will locally rise. The temperature can reach the boiling point of the fluid. When the fluid cools down, implosions can occur that can damage the transmission 301, even the hardmetal parts thereof.
The further alternative continuously variable transmission 301 differs from the previously discussed continuously variable transmissions 1, 101, 201 in that it is provided with one or more pressure sensors 391 to detect the pressure in the volumes VI, V2 of the gear pumps 2, 3, a pressurization element 392 to adjust the pressure in the respective volumes VI, V2 and a control unit 393 that is operationally connected to the one or more pressure sensors 391 and the pressurization element 392 to control the pressurization element 392 in response to pressure signals from the one or more pressure sensors 391. By measuring the pressure with the one or more pressure sensors 391, variations in pressure in the gear pumps 2, 3 as a result of the cavitation can be detected and the pressurization element 392 can be controlled accordingly to compensate and keep the pressure more constant. Additionally or alternatively, the pressurization element 392 may be used to increase the pressure in the gear pumps 2, 3 up to a level at which cavitation is decreased or does not occur at all.
Optionally, the continuously variable transmission 1, 101, 201, 301 according to the invention may allow for the second pump 3 to be completely closed,
i.e. the pump volume V2 essentially becomes zero and the transmission ratio is zero as well. Hence, the gears 33, 34 of the second gear pump 3 will no longer be rotated and the output shaft 35 will no longer provide an output to the wheels W. Preferably, a bypass channel (not shown) is provided that bypasses the second gear pump 3. The bypass channel preferably is only in fluid communication with the ducts 11, 12 when the second gear pump 3 is completely closed to ensure that the fluid flow Fl through the first gear pump 2 can be maintained without any significant build-up of pressure. In particular, the first gear pump 2 should be able to keep running at the same speed as the input shaft 25 that is driven by the engine E. In this manner, the continuously variable transmission 1, 101, 201, 301 can effectively be used as a coupling/decoupling between the engine E and the wheels W, thus eliminating the need for a conventional, separate clutch.
It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention.
In particular, it will be apparent to one skilled in the art that the gear pumps of the previously described embodiment do not necessarily need to be placed in a single housing. When the gear pumps are arranged in separate housings, the connecting member can connect the adjustment members in said separate housings mechanically, hydraulically or even electronically, e.g. with the use of controlled servo motors. Consequently, the overlap directions Dl, D2 do not necessarily need to be parallel. The connecting member may provide for a change in direction between the overlap direction Dl of the first gear pump and the overlap direction D2 of the second gear pump.
More in particular, it will be apparent to one skilled in the art that generic features of one embodiment can be applied to the other embodiments as well. Each of the embodiments can for example be controlled mechanically or hydraulically, depending on the requirements of the continuously variable transmission. Moreover, the gear pumps in each of the embodiments can be housed in the same or a single housing, or in separate housings interconnected by the connecting member. Finally, it will be apparent that the switching capability introduced by the control member of the fourth embodiment can be applied just as well to the other embodiments when one provides the required additional ducts and one or more switching elements for switching between the previously disclosed ducts and said additional ducts .
Other variations are envisioned, including different types of gears, i.e. colloidal gears, worm gears, internal gears, external gears, gerotor gears or a combination thereof.

Claims (8)

CONCLUSIESCONCLUSIONS 1. Continu variabele transmissie omvattend een eerste tandradpomp en een tweede tandradpomp, waarbij elke tandradpomp een fluïduminlaat, een fluïdumuitlaat en een pompvolume tussen de fluïduminlaat en de fluïdumuitlaat omvat, waarbij elke tandradpomp verder een eerste tandrad omvat dat roteerbaar is binnen het respectievelijke pompvolume rond een eerste tandradhartlijn en tweede tandrad dat roteerbaar is binnen het respectievelijke pompvolume rond een tweede tandradhartlijn en ingrijpend op het eerste tandrad over een overlapafstand in een overlaprichting evenwijdig aan de eerste tandradhartlijn voor het verplaatsen van een fluïdum door het respectievelijk pompvolume van de respectievelijke fluïduminlaat naar de respectievelijke fluïdumuitlaat, waarbij de fluïdumuitlaat van de eerste tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de tweede tandradpomp en waarbij de fluïdumuitlaat van de tweede tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de eerste tandradpomp, waarbij elke tandradpomp verder een insteldeel omvat voor het instellen van het pompvolume van de respectievelijke tandradpomp, waarbij het insteldeel van de eerste tandradpomp en het insteldeel van de tweede tandradpomp onderling verbonden zijn door een verbindingsdeel dat is ingericht voor het instellen van het pompvolume van de eerste tandradpomp en het pompvolume van de tweede tandradpomp in een omgekeerde correlatie ten opzichte van elkaar, waarbij de eerste tandradpomp is voorzien van een toevoerkanaal dat zich uitstrekt langs een baan dat vloeistofverbinding toelaat van de respectievelijke pompvolume naar een holte tussen de in elkaar grijpende tanden van de tandwielen van de eerste tandradpomp wanneer de holte in volume toeneemt en een evacuatiekanaal dat zich uitstrekt langs een baan dat Continuously variable transmission comprising a first gear pump and a second gear pump, each gear pump comprising a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, each gear pump further comprising a first gear which is rotatable within the respective pump volume about a first cog axis and second cog rotatable within the respective pump volume about a second cog axis and engaging the first cog over an overlap distance in an overlap direction parallel to the first cog axis to displace a fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, the fluid outlet of the first gear pump being in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump being in fluid communication with the fluid inlet t of the first gear pump, each gear pump further comprising an adjusting part for adjusting the pump volume of the respective gear pump, the adjusting part of the first gear pump and the adjusting part of the second gear pump being interconnected by a connecting part arranged for adjusting of the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation with each other, the first gear pump having a supply channel extending along a path allowing fluid communication from the respective pump volume to a cavity between the interlocking teeth of the gears of the first gear pump as the cavity increases in volume and an evacuation channel extending along a path that 2 4 vloeistofverbinding toelaat van de holte tussen de in elkaar grijpende tanden van de tandwielen van de eerste tandradpomp naar het respectievelijke pompvolume wanneer de holte in volume afneemt.2 4 allows fluid connection from the cavity between the interlocking teeth of the gears of the first gear pump to the respective pump volume as the cavity decreases in volume. 2. Continu variabele transmissie volgens conclusie 1, waarbij de tweede tandradpomp is voorzien van een toevoerkanaal dat zich uitstrekt langs een baan dat vloeistofverbinding toelaat van het respectievelijke pompvolume naar een holte tussen de in elkaar grijpende tanden van de tandwielen van de tweede tandradpomp wanneer de holte in volume afneemt en een evacuatiekanaal dat zich uitstrekt langs een baan dat vloeistofverbinding toelaat vanuit de holte tussen de in elkaar grijpende tanden van de tandwielen van de tweede tandradpomp naar het respectievelijke pompvolume wanneer de holte in volume afneemt.Continuously variable transmission according to claim 1, wherein the second gear pump comprises a feed channel extending along a path allowing fluid communication from the respective pump volume to a cavity between the interlocking teeth of the gears of the second gear pump when the cavity decreases in volume and an evacuation channel extending along a path allowing fluid communication from the cavity between the interlocking teeth of the gears of the second gear pump to the respective pump volume as the cavity decreases in volume. 3. Continu variabele transmissie omvattend een eerste tandradpomp en een tweede tandradpomp, waarbij elke tandradpomp een fluïduminlaat, een fluïdumuitlaat en een pompvolume tussen de fluïduminlaat en de fluïdumuitlaat omvat, waarbij elke tandradpomp verder een eerste tandrad omvat dat roteerbaar is binnen het respectievelijke pompvolume rond een eerste tandradhartlijn en tweede tandrad dat roteerbaar is binnen het respectievelijke pompvolume rond een tweede tandradhartlijn en ingrijpend op het eerste tandrad over een overlapafstand in een overlaprichting evenwijdig aan de eerste tandradhartlijn voor het verplaatsen van een fluïdum door het respectievelijk pompvolume van de respectievelijke fluïduminlaat naar de respectievelijke fluïdumuitlaat, waarbij de fluïdumuitlaat van de eerste tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de tweede tandradpomp en waarbij de fluïdumuitlaat van de tweede tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de eerste tandradpomp, waarbij elke tandradpomp verder een insteldeel omvat voor het instellen van het pompvolume van de respectievelijke tandradpomp, waarbij het insteldeel van de eerste tandradpomp en het insteldeel van de tweede tandradpomp onderling verbonden zijn door een verbindingsdeel dat is ingericht voor het instellen van het pompvolume van de eerste tandradpomp en het pompvolume van de tweede tandradpomp in een omgekeerde correlatie ten opzichte van elkaar, waarbij de transmissie is voorzien van een of meer bufferelementen teneinde drukverschillen in de respectievelijke pompvolumes te absorberen.Continuously variable transmission comprising a first gear pump and a second gear pump, each gear pump comprising a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, each gear pump further comprising a first gear which is rotatable within the respective pump volume about a first cog axis and second cog rotatable within the respective pump volume about a second cog axis and engaging the first cog over an overlap distance in an overlap direction parallel to the first cog axis to displace a fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, the fluid outlet of the first gear pump being in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump being in fluid communication with the fluid inlet t of the first gear pump, each gear pump further comprising an adjusting part for adjusting the pump volume of the respective gear pump, the adjusting part of the first gear pump and the adjusting part of the second gear pump being interconnected by a connecting part arranged for adjusting of the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation with each other, the transmission being provided with one or more buffer elements to absorb pressure differences in the respective pump volumes. 4. Continu variabele transmissie volgens conclusie 3, waarbij de een of meer bufferelementen gevormd zijn door kleine kamers met variabele volumes die in directe verbinding staan met de respectievelijke pompvolumes, waarbij het variabele volume van de kamers voorbelast is naar het kleinste volume.Continuously variable transmission according to claim 3, wherein the one or more buffer elements are formed by small chambers of variable volumes which are in direct communication with the respective pump volumes, the variable volume of the chambers being preloaded to the smallest volume. 5. Continu variabele transmissie omvattend een eerste tandradpomp en een tweede tandradpomp, waarbij elke tandradpomp een fluïduminlaat, een fluïdumuitlaat en een pompvolume tussen de fluïduminlaat en de fluïdumuitlaat omvat, waarbij elke tandradpomp verder een eerste tandrad omvat dat roteerbaar is binnen het respectievelijke pompvolume rond een eerste tandradhartlijn en tweede tandrad dat roteerbaar is binnen het respectievelijke pompvolume rond een tweede tandradhartlijn en ingrijpend op het eerste tandrad over een overlapafstand in een overlaprichting evenwijdig aan de eerste tandradhartlijn voor het verplaatsen van een fluïdum door het respectievelijk pompvolume van de respectievelijke fluïduminlaat naar de respectievelijke fluïdumuitlaat, waarbij de fluïdumuitlaat van de eerste tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de tweede tandradpomp en waarbij de fluïdumuitlaat van de tweede tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de eerste tandradpomp, waarbij elke tandradpomp verder een insteldeel omvat voor het instellen van het pompvolume van de respectievelijke tandradpomp, waarbij het insteldeel van de eerste tandradpomp en het insteldeel van de tweede tandradpomp onderling verbonden zijn door een verbindingsdeel dat is ingericht voor het instellen van het pompvolume van de eerste tandradpomp en het pompvolume van de tweede tandradpomp in een omgekeerde correlatie ten opzichte van elkaar, waarbij de transmissie is voorzien van een of meer druksensoren teneinde de druk in de respectievelijke pompvolumes te detecteren, een op druk breng element teneinde de druk in de respectievelijke pompvolumes aan te passen en een regeleenheid die operationeel verbonden is met de een of meer druksensoren en het op druk breng element teneinde het op druk breng element te regelen in reactie op druksignalen van de een of meer druksensoren.Continuously variable transmission comprising a first gear pump and a second gear pump, each gear pump comprising a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, each gear pump further comprising a first gear which is rotatable within the respective pump volume about a first cog axis and second cog rotatable within the respective pump volume about a second cog axis and engaging the first cog over an overlap distance in an overlap direction parallel to the first cog axis to displace a fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, the fluid outlet of the first gear pump being in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump being in fluid communication with the fluid inlet t of the first gear pump, each gear pump further comprising an adjusting part for adjusting the pump volume of the respective gear pump, the adjusting part of the first gear pump and the adjusting part of the second gear pump being interconnected by a connecting part arranged for adjusting of the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation with each other, the transmission comprising one or more pressure sensors to detect the pressure in the respective pump volumes, a pressurizing element to adjust pressure in the respective pump volumes and a control unit operatively connected to the one or more pressure sensors and the pressurizing element to control the pressurizing element in response to pressure signals from the one or more pressure sensors. 6. Continu variabele transmissie volgens conclusie 5, waarbij de regeleenheid is ingericht voor het regelen van het op druk breng element teneinde de druk in de tandradpompen te laten toenemen tot een niveau dat cavitatie vermindert.Continuously variable transmission according to claim 5, wherein the control unit is adapted to control the pressurizing element in order to increase the pressure in the gear pumps to a level that reduces cavitation. 7. Continu variabele transmissie omvattend een eerste tandradpomp en een tweede tandradpomp, waarbij elke tandradpomp een fluïduminlaat, een fluïdumuitlaat en een pompvolume tussen de fluïduminlaat en de fluïdumuitlaat omvat, waarbij elke tandradpomp verder een eerste tandrad omvat dat roteerbaar is binnen het respectievelijke pompvolume rond een eerste tandradhartlijn en tweede tandrad dat roteerbaar is binnen het respectievelijke pompvolume rond een tweede tandradhartlijn en ingrijpend op het eerste tandrad over een overlapafstand in een overlaprichting evenwijdig aan de eerste tandradhartlijn voor het verplaatsen van een fluïdum door het respectievelijk pompvolume van de respectievelijke fluïduminlaat naar de respectievelijke fluïdumuitlaat, waarbij de fluïdumuitlaat van de eerste tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de tweede tandradpomp en waarbij de fluïdumuitlaat van de tweede tandradpomp is aangebracht in fluïdumverbinding met de fluïduminlaat van de eerste tandradpomp, waarbij elke tandradpomp verder een insteldeel omvat voor het instellen van het pompvolume van de respectievelijke tandradpomp, waarbij het insteldeel van de eerste tandradpomp en het insteldeel van de tweede tandradpomp onderling verbonden 5 zijn door een verbindingsdeel dat is ingericht voor het instellen van het pompvolume van de eerste tandradpomp en het pompvolume van de tweede tandradpomp in een omgekeerde correlatie ten opzichte van elkaar, waarbij het pompvolume van een van de tandradpompen verminderbaar is tot nul.Continuously variable transmission comprising a first gear pump and a second gear pump, each gear pump comprising a fluid inlet, a fluid outlet and a pump volume between the fluid inlet and the fluid outlet, each gear pump further comprising a first gear which is rotatable within the respective pump volume about a first cog axis and second cog rotatable within the respective pump volume about a second cog axis and engaging the first cog over an overlap distance in an overlap direction parallel to the first cog axis to displace a fluid through the respective pump volume from the respective fluid inlet to the respective fluid outlet, the fluid outlet of the first gear pump being in fluid communication with the fluid inlet of the second gear pump and the fluid outlet of the second gear pump being in fluid communication with the fluid inlet t of the first gear pump, each gear pump further comprising an adjusting part for adjusting the pump volume of the respective gear pump, the adjusting part of the first gear pump and the adjusting part of the second gear pump being interconnected by a connecting part adapted for the setting the pump volume of the first gear pump and the pump volume of the second gear pump in an inverse correlation with each other, the pump volume of one of the gear pumps being reducible to zero. 10 8. Continu variabele transmissie volgens conclusie 7, waarbij de transmissie verder een bypass kanaal omvat dat is ingericht teneinde een omleiding te verschaffen om het pompvolume van de ene tandradpomp wanneer het pompvolume gereduceerd is tot nul.The continuously variable transmission of claim 7, wherein the transmission further comprises a bypass channel arranged to provide a bypass around the pump volume of the one gear pump when the pump volume is reduced to zero.
NL2021574A 2018-09-06 2018-09-06 Continuously variable transmission and transmission system NL2021574B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
NL2021574A NL2021574B1 (en) 2018-09-06 2018-09-06 Continuously variable transmission and transmission system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL2021574A NL2021574B1 (en) 2018-09-06 2018-09-06 Continuously variable transmission and transmission system

Publications (1)

Publication Number Publication Date
NL2021574B1 true NL2021574B1 (en) 2020-04-30

Family

ID=70549862

Family Applications (1)

Application Number Title Priority Date Filing Date
NL2021574A NL2021574B1 (en) 2018-09-06 2018-09-06 Continuously variable transmission and transmission system

Country Status (1)

Country Link
NL (1) NL2021574B1 (en)

Similar Documents

Publication Publication Date Title
US4272993A (en) Hydraulically controlled differential
KR101454057B1 (en) Power split transmission
US3033333A (en) Transmission
US5971880A (en) Infinitely variable ratio transmission
US3123975A (en) Ebert
US5839985A (en) Differential apparatus having a thrust washer
US5669761A (en) Discharge control apparatus of hydraulic pump for automatic transmission
WO2009049514A1 (en) Mechanical-hydraulic continuously variable transmission, and the method thereof, and vehicle mechanical-hydraulic continuously variable transmission
US4729261A (en) Stepless transmission
NL2011584C2 (en) Transmission.
NL2021574B1 (en) Continuously variable transmission and transmission system
US20150292617A1 (en) Control mechanism for a continuously variable transmission
KR20100015712A (en) A continuous variable transmission assembly
KR20140140011A (en) Variable displacement gear pump
US11280402B2 (en) Continuously variable transmission and transmission system
WO2011158167A2 (en) Fluidic gear machine with flow rate regulation
KR100335600B1 (en) Stepless transmission for vehicles
JP4217549B2 (en) Hydraulic-mechanical transmission
US20120297758A1 (en) Large Displacement Variator
US2897688A (en) Hydraulic transmission mechanism
US7025700B1 (en) Closed-loop hydraulic adjustable slip differential
CN104981607A (en) Hydraulic gear motor, gear pump and gearbox with continuously variable parameters
US11668381B2 (en) Transmission structure
NL2003726C2 (en) DISPLACEMENT PUMP WITH ADJUSTABLE BATTLE VOLUME AND A DRIVE AND VEHICLE PROVIDED WITH THAT, AND METHOD FOR THE APPLICATION THEREOF.
BE1026790B1 (en) Variable speed drive for a fluid pump and fluid pump equipped with it