Powershift transmission and method for shifting a powershift transmission

Abstract

Powershift transmission (1) with at least two powershift elements (11, 13, 15), wherein the powershift transmission (1) can assume different switching states, wherein each switching state of the switching states is assigned a gear of at least three gears (G1, G2, G3, G4), wherein in each switching state of the switching states one powershift element of the at least two powershift elements (11, 13, 15) is closed, wherein one power shift element of the at least two power shift elements (11, 13, 15) is closed in the switching state associated with a lowest gear or a highest gear of the at least three gears (G1, G2, G3, G4) and is open in the switching states associated with the remaining gears of the at least three gears (G1, G2, G3, G4), characterized in that the powershift transmission (1) further comprises a first shaft (5), wherein the first shaft (5) is only in the power flow when the powershift transmission (1) is in the shifting state associated with the lowest gear, wherein the at least two load switching elements (11, 13, 15) have three load switching elements, and wherein the powershift transmission (1) further comprises a first shifting element (57) and a second shifting element (59), wherein the first shifting element (57) and the second shifting element (59) are arranged coaxially on an output shaft (9) and can each be connected to a corresponding spur gear by a common coupling element (61), so that the output shaft (9) is connected to the corresponding spur gear in a rotationally fixed manner.

Description

[0001] The present invention relates to a powershift transmission and a method for shifting a powershift transmission.

[0002] Powershift transmissions are known from the prior art. For example, powershift transmissions that have powershift elements can assume different shift states, with each shift state being assigned one of several gears, with one of the powershift elements being engaged in each shift state.

[0003] In general, it is desirable for powershift transmissions to provide a transmission that is overall weight-saving and particularly compact, in which the time required for a gear change is kept short.

[0004] DE 10 2021 211 734 B3 relates to a transmission comprising an input shaft, a first intermediate shaft, and a second intermediate shaft. According to DE 10 2021 211 734 B3, a first and a second fixed gear are arranged on the input shaft in a rotationally fixed manner, wherein the first fixed gear meshes with a first idler gear mounted on the first intermediate shaft, and the second fixed gear meshes with a second idler gear mounted on the first intermediate shaft, and wherein the first idler gear is connectable to the first intermediate shaft via a first shifting element, and the second idler gear via a second shifting element. One of the two idler gears comprising the first and second idler gears meshes with a third idler gear rotatably mounted on the second intermediate shaft, which third idler gear is connectable to the second intermediate shaft via a third shifting element, wherein the first and second intermediate shafts are rotationally fixedly connected to an output.

[0005] DE 25 35 700 A1 discloses a manual transmission having an equal number of forward and reverse gears shiftable under load. Each of the three shafts has a pair of selectively actuated clutches with respective input elements and a common output element. Gears are attached to the respective clutch elements of the first shaft, which mesh via intermediate gears with further gears attached to the respective clutch elements of the second shaft. These latter gears mesh directly with gears attached to the clutches of the third shaft. One of the intermediate gears is attached to an input shaft. One of the gears on the third shaft drives an output shaft.

[0006] DE 600 07 784 T2 discloses a parallel shaft transmission comprising: a first input shaft, a second input shaft, and a countershaft arranged parallel to one another. The parallel shaft transmission further comprises at least one set of a first gear ratio gear train, each set including a first gear ratio drive gear arranged on the first input shaft and a first gear ratio output gear arranged on the countershaft, the first gear ratio drive gear and the first gear ratio output gear meshing with each other; at least one first clutch means arranged on the first input shaft, the first clutch means rotationally connecting and disconnecting the first gear ratio drive gear to and from the first input shaft.The parallel shaft transmission also includes at least one set of second gear ratio gear trains, each set including a second gear ratio drive gear disposed on the second input shaft and a second gear ratio driven gear disposed on the countershaft, the second gear ratio drive gear and the second gear ratio driven gear meshing with each other; at least one second clutch means disposed on the second input shaft, the second clutch means rotationally connecting and disconnecting the second gear ratio drive gear from the second input shaft.The parallel shaft transmission finally comprises a connecting gear train which is used to transmit power from the first input shaft to the second input shaft, wherein the connecting gear train carries out the power transmission from the first input shaft to the second input shaft through a gear provided on the intermediate shaft which is arranged parallel to the first input shaft. A power take-off transmission for an agricultural utility vehicle is known from DE 10 2021 113 560 A1. The power take-off transmission comprises an input shaft, an output shaft, a first intermediate shaft, a second intermediate shaft and a first gear stage. The first gear stage is arranged such that the input shaft has a first fixed gear and the first intermediate shaft has a second fixed gear and the second intermediate shaft has a third fixed gear, wherein only the first fixed gear meshes with the second fixed gear and the first fixed gear meshes with the third fixed gear.

[0007] DE 10 2013 110 316 A1 discloses a power take-off transmission for an agricultural work machine, in particular for a tractor. The power take-off transmission comprises a first partial transmission, to which a first transmission shaft is assigned, and at least one further partial transmission, to which a further transmission shaft spaced from the first transmission shaft is assigned, wherein each of the transmission shafts can be brought into drive connection with a common power take-off shaft via at least one transmission gear stage, and wherein each of the transmission shafts can be brought into drive connection with an input shaft of the power take-off transmission (12) by closing a friction clutch assigned to the respective partial transmission.

[0008] US 2020 / 332 862 A1 describes a multi-speed turbomachine transmission that may include an input shaft and a plurality of input shaft gears arranged on the input shaft. The transmission may include one or more clutch shafts, one or more clutch shaft input gears arranged on the one or more clutch shafts and each meshing with at least one of the plurality of input shaft gears, at least one clutch shaft output gear attached to each clutch shaft, and a clutch connected to each clutch shaft and configured to selectively connect the one or more clutch shaft input gears to the at least one clutch shaft output gear. The transmission may further include an output shaft and at least one output shaft gear connected to the output shaft and meshing with the at least one clutch shaft output gear.

[0009] It is therefore the object of the present invention to provide an overall weight-saving and particularly compact transmission in which the time period for a gear shift is kept short.

[0010] According to a first aspect of the invention, the stated object is achieved by a powershift transmission having the features of patent claim 1. The powershift transmission has at least two powershift elements. The powershift transmission can assume different shifting states. Each shifting state of the shifting states is assigned to one of at least three gears, wherein in each shifting state of the shifting states, one powershift element of the at least two powershift elements is closed. One powershift element of the at least two powershift elements is closed in the shifting state assigned to a lowest gear or a highest gear of the at least three gears and is open in the shifting states assigned to the remaining gears of the at least three gears.

[0011] The powershift transmission has at least two powershift elements. Preferably, the powershift transmission has two powershift elements. Particularly preferably, the powershift transmission has three powershift elements. In other words, in this case, the at least two powershift elements have three powershift elements, namely a first powershift element, a second powershift element, and a third powershift element. Each of the powershift elements is preferably designed as a wet- or dry-running friction shift element. Each of the powershift elements can preferably be switched independently of the other powershift elements from a closed state to an open state and from an open state to a closed state, wherein a switching operation comprises an opening or a closing.Preferably, each of the powershift elements in the closed state provides a rotationally fixed connection between two components of the powershift transmission, such as a shaft and a selector shaft. This rotationally fixed connection can ensure a power flow or torque transmission between the two components. Preferably, in the open state, each of the powershift elements does not provide a rotationally fixed connection between the two components, so that no power flow or torque transmission occurs between the two components.

[0012] Each shift state of the shift states is assigned one of at least three gears. Thus, at least three gears are provided. It has been found that the present invention is particularly advantageous for powershift transmissions that can assume at least three shift states, each of these shift states being assigned a corresponding gear of at least three gears. Preferably, the powershift transmission can assume three shift states, each of the three shift states being assigned one of three gears. Particularly preferably, the powershift transmission can assume four shift states, each of the four shift states being assigned one of four gears.

[0013] In each switching state of the switching states, one load switching element of the at least two load switching elements is closed. Preferably, when one load switching element is closed, the other load switching element or the other load switching elements are open. For example, when a first load switching element is closed, a second load switching element and a third load switching element are open. Likewise, for example, when a second load switching element is closed, a first load switching element and a third load switching element are open. For example, when a third load switching element is closed, a first load switching element and a second load switching element are open.

[0014] As already described, one powershift element of the at least two powershift elements is closed in the switching state associated with a lowest gear or a highest gear of the at least three gears, and open in the switching states associated with the remaining gears of the at least three gears. Preferably, one powershift element of the at least two powershift elements is a first powershift element. In this case, the first powershift element is closed in the switching state associated with a lowest gear or a highest gear of the at least three gears, and open in the switching states associated with the remaining gears of the at least three gears.In this case, a second powershift element and / or a third powershift element is / are preferably open in the switching state assigned to a lowest gear or a highest gear of the at least three gears and closed in the switching states assigned to the remaining gears of the at least three gears. Preferably, at least the second powershift element or the third powershift element is / are each closed in at least one of the switching states assigned to the remaining gears of the at least three gears. For example, in a first gear, the first powershift element can be closed, in a second gear the second powershift element can be closed, in a third gear the third powershift element can be closed, and in a fourth gear the second powershift element can be closed again.

[0015] The present invention can relate to two alternatives, namely the lowest gear on the one hand and the highest gear on the other. When the powershift element is closed in the shift state associated with a lowest gear and open in the shift states associated with the other gears, the other gears are the gears immediately adjacent to the lowest gear and including the highest gear. In the event that three gears are provided and the lowest gear is first gear, the other gears are second gear and third gear. In the preferred case in which four gears are provided and the lowest gear is first gear, the other gears are second gear, third gear and fourth gear.When the powershift element is closed in the shift state associated with a highest gear and open in the shift states associated with the other gears, the other gears are the gears immediately adjacent to the highest gear and including the lowest gear. In the event that three gears are provided and the highest gear is the third gear, the other gears are the first gear and the second gear. In the preferred case that four gears are provided and the highest gear is the fourth gear, the other gears are the first gear, the second gear, and the third gear.

[0016] Because the powershift transmission is designed in such a way that one powershift element of the at least two powershift elements is closed in the shift state assigned to a lowest gear or a highest gear of the at least three gears and is open in the shift states assigned to the other gears of the at least three gears, in the event that the lowest gear is affected, those components can be designed to be mechanically robust which are only in the power flow when the powershift transmission is in the shift state assigned to the lowest gear and in the event that the highest gear is affected, those components can be designed to be mechanically less robust which are only in the power flow when the powershift transmission is in the shift state assigned to the highest gear.This mechanically more or less robust design allows the other components that are in the power flow when the shift states associated with the other gears are present to be dimensioned accordingly to the corresponding mechanical loads. If the lowest gear is affected, the other components can be designed to be less mechanically robust, and if the highest gear is affected, the other components can be designed to be more mechanically robust.Thus, in the powershift transmission, the components that are exposed to high torques can be designed to be particularly robust mechanically, and the components that are exposed to lower torques can be designed to be less robust, so that an overall weight-saving and particularly compact transmission can be provided, in which in particular the components that are exposed to lower torques can have low moments of inertia, which simplifies a change in the angular velocity of these components and thus the components can adapt their angular velocity particularly quickly during a gear shift, which in turn keeps the time period for a gear shift short.

[0017] In summary, it can be stated that an overall weight-saving and particularly compact transmission can be provided in which the time required for a gear change is kept to a minimum.

[0018] The powershift transmission preferably has an input shaft and an output shaft, wherein for each shifting state of the transmission, different components of the transmission are located in a power flow associated with the corresponding shifting state. Each power flow ensures that, viewed in the direction of power flow from the input shaft to the output shaft, a rotational movement of the input shaft causes a rotational movement of the output shaft, wherein the components that ensure the conversion of the rotational movement of the input shaft into the rotational movement of the output shaft are located in the power flow. Thus, a corresponding shifting state and a corresponding power flow are preferably provided for each gear.

[0019] The powershift transmission preferably has an additional transmission unit, such as a splitter transmission unit, which can condense the gear sequence of the powershift transmission by dividing the gears of the powershift transmission by small increments of the additional transmission unit, thus increasing the total number of available gears. Each of the at least three gears can thus be assigned to a corresponding driving range of at least three driving ranges. A first gear of four gears of the powershift transmission is preferably assigned to a first driving range, which is intended for the lowest driving speeds.

[0020] Preferably, the powershift transmission is configured such that, in the shift state associated with the lowest gear of the at least three gears, the powershift transmission can be operated within a slip range in which a tire coupled to the powershift transmission, with a surface on which the tire rolls, forms a slip that is equal to or greater than a predetermined minimum slip. Preferably, the slip range is limited by a predetermined minimum slip and a predetermined maximum slip, wherein the slip that the tire forms relative to the surface is equal to or greater than the predetermined minimum slip and equal to or less than the predetermined maximum slip.The slip that the tire creates with the ground is preferably defined by a speed difference between a speed of the tire and a speed of a fictitious tire that simulates a section of the ground in contact with the tire and whose movement simulates the movement of the section of the ground relative to the tire. Preferably, the slip is defined by a quotient of a difference between the speed of the tire and the speed of the fictitious tire and the speed of the tire, with the difference forming the dividend and the speed of the tire forming the divisor.

[0021] Situations can therefore arise in which the drive forces transferred to the tire are so great that slip occurs which is greater than the specified minimum slip, which in turn means that not the entire theoretically possible drive torque of the prime mover for driving the tire is available at the input shaft of the powershift transmission. These situations occur particularly in the gearshift state assigned to the lowest gear of at least three gears. In other words, it can also be said that the lowest gear, first gear or the first driving range is within the slip limit, i.e. the slip in first gear is equal to or greater than the specified minimum slip and equal to or less than the specified maximum slip. In this case, the maximum slip can even be 100%.Preferably, however, the maximum slip is specified so that it is below 100%, for example less than 30%. In particular, since the slip in first gear or in the first driving range assigned to first gear is equal to or greater than the specified minimum slip, it is ensured that the torque to be transmitted by the powershift transmission in the lowest gear is limited from above. The powershift element of the at least two powershift elements that is closed when assigned to the lowest gear is shifted is therefore only loaded up to a certain limit. The same applies to the components of the powershift transmission that are in the power flow in the lowest gear or in the first driving range, since the torque to be transmitted is limited.In particular, a gear ratio down to low speed in the direction of power flow from the drive engine to the tire seen in front of the powershift element of the at least two powershift elements which is engaged in the shift state assigned to the lowest gear, only influences the powershift element engaged in the lowest gear or the clutch for the first driving range up to the maximum main shaft torque, which can also be referred to as the maximum output shaft torque, i.e. the maximum torque applied to the output shaft due to the slip. In particular, when the powershift transmission provides a gear ratio down to low speed for the lowest gear, the specified minimum slip ensures that those components which are only in the power flow when the powershift transmission is in the shift state assigned to the lowest gear need to be designed to be less mechanically robust.

[0022] Preferably, the powershift transmission does not provide for a low-speed ratio for gears higher than the lowest gear, such as second gear, third gear, and fourth gear. If these gears are assigned corresponding driving ranges, these driving ranges preferably do not have a significant low-speed ratio, and the components in the power flow for these gears or driving ranges can thus be dimensioned smaller.

[0023] In one embodiment, one powershift element of the at least two powershift elements is closed in the shift state assigned to the lowest gear of the at least three gears and open in the shift states assigned to the remaining gears of the at least three gears. Preferably, the one powershift element is only in the power flow in the lowest gear and not in the remaining gears. Because one powershift element of the at least two powershift elements is closed in the shift state assigned to a lowest gear of the at least three gears and is open in the shift states assigned to the remaining gears of the at least three gears, the one powershift element and those components that are in the power flow when the powershift transmission is in the shift state assigned to the lowest gear can be designed to be mechanically robust.The remaining components of the powershift transmission, which are in the power flow when the powershift transmission is in the shift states assigned to the remaining gears of at least three gears and are not in the power flow when the powershift transmission is in the shift state assigned to the lowest gear, can be designed to be correspondingly less mechanically robust, allowing the powershift transmission to be designed to be lightweight and particularly compact overall. Furthermore, the remaining components can be designed to have particularly low moments of inertia, allowing the time span for a shifting operation in which these remaining components must change their angular velocity to be kept short.In particular, the transmission can thus provide components located in the power flow in a third gear of four gears with a low moment of inertia compared to the prior art, thereby simplifying a change in the angular velocity of these components.

[0024] In one embodiment, one powershift element of the at least two powershift elements is closed in the shift state associated with the highest gear of the at least three gears and open in the shift states associated with the remaining gears of the at least three gears. Preferably, the one powershift element is only in the power flow in the highest gear and not in the remaining gears. Because the one powershift element of the at least two powershift elements is closed in the shift state associated with the highest gear of the at least three gears and open in the shift states associated with the remaining gears of the at least three gears, the one powershift element and those components that are in the power flow when the powershift transmission is in the shift state associated with the highest gear can be designed to be mechanically less robust.The remaining components of the powershift transmission, which are in the power flow when the powershift transmission is in the shift states assigned to the other gears of the at least three gears and are not in the power flow when the powershift transmission is in the shift state assigned to the highest gear, can be designed to be correspondingly more mechanically robust, whereby the powershift transmission as a whole can be designed to be weight-saving and particularly compact. In addition, the one powershift element and those components which are in the power flow when the powershift transmission is in the shift state assigned to the highest gear can be designed such that they have particularly low moments of inertia, whereby the time span for a shifting operation in which these remaining components have to change their angular velocity can be kept short.In particular, the transmission for components located in the power flow in a second gear of four gears can be designed to be more mechanically robust than the state of the art, so that greater torques can be transmitted by these components.

[0025] In one embodiment, the powershift transmission further comprises a first spur gear stage, wherein the first spur gear stage is only in the power flow when the powershift transmission is in the shift state associated with the lowest gear. Therefore, the first spur gear stage is preferably only in the power flow when the powershift transmission is in the shift state associated with the lowest gear, and in the shift states associated with the other gears, the first spur gear stage is not in the power flow. Therefore, the first spur gear stage can be adapted to the loads occurring in the lowest gear and designed accordingly robustly.In particular, additional spur gear stages, such as a third spur gear stage, a fourth spur gear stage, a fifth spur gear stage, and / or a sixth spur gear stage, can be adapted, at least in sections, to the loads occurring in the remaining gears, such as a second gear, a third gear, and / or a fourth gear, and thus be dimensioned to be less mechanically robust and weight-saving. In particular, the transmission for a third gear can thus provide components located in the power flow with a lower moment of inertia compared to the prior art, thereby simplifying changes in the angular velocity of these components.

[0026] According to the first aspect of the invention, the powershift transmission further comprises a first shaft, wherein the first shaft is only in the power flow when the powershift transmission is in the shift state associated with the lowest gear. Therefore, the first shaft is preferably only in the power flow when the powershift transmission is in the shift state associated with the lowest gear, and in the shift states associated with the other gears, the first shaft is not in the power flow. Therefore, the first shaft can be adapted to the loads occurring in the lowest gear and designed to be correspondingly robust.In particular, additional shafts, such as a second shaft, can be adapted, at least in sections, to the loads occurring in the remaining gears, such as a second gear, a third gear, and / or a fourth gear, and thus be dimensioned to be less mechanically robust and weight-saving. In particular, the transmission for a third gear can thus provide components in the power flow with a lower moment of inertia compared to the prior art, which simplifies changing the angular velocity of these components.

[0027] In one embodiment, the powershift transmission additionally has a second spur gear stage, wherein the second spur gear stage is only fully in the power flow when the powershift transmission is in the shift state associated with the lowest gear. Preferably, a spur gear of the second spur gear stage, such as a third spur gear, is only in the power flow when the powershift transmission is in the shift state associated with the lowest gear, since, for example, a further spur gear of the second spur gear stage, such as a fourth spur gear, can be both a spur gear of the second spur gear stage and a spur gear of a further spur gear stage, such as a fifth spur gear stage, and the further spur gear stage is in the power flow when the powershift transmission is in a shift state associated with one of the remaining gears, such as a second gear.Therefore, the second spur gear stage is preferably only completely in the power flow or a spur gear of the second spur gear stage, such as the third spur gear, is preferably only in the power flow when the powershift transmission is in the shift state assigned to the first gear, and in the shift states assigned to the other gears, the second spur gear stage is not completely in the power flow because, for example, the third spur gear is not in the power flow, but, for example, the fourth spur gear is in the power flow because, for example, it is a spur gear of the fifth spur gear stage.Because the powershift transmission also has a second spur gear stage, the second spur gear stage being fully in the power flow only when the powershift transmission is in the shift state associated with the lowest gear, the second spur gear stage is preferably only in the power flow when the powershift transmission is in the shift state associated with the lowest gear, and in the shift states associated with the other gears, the second spur gear stage is not in the power flow. Therefore, the second spur gear stage can be adapted, at least in sections, to the loads occurring in the lowest gear and, at least in sections, can be designed to be correspondingly robust.In particular, additional spur gear stages, such as a third spur gear stage, a fourth spur gear stage, a fifth spur gear stage, and / or a sixth spur gear stage, can be adapted, at least in sections, to the loads occurring in the remaining gears, such as a second gear, a third gear, and / or a fourth gear, and thus be dimensioned to be less mechanically robust and weight-saving. In particular, the transmission for a third gear can thus provide components located in the power flow with a lower moment of inertia compared to the prior art, thereby simplifying changes in the angular velocity of these components.

[0028] In one embodiment, a section of a powershift element of the at least two powershift elements is connected in a rotationally fixed manner to a section of a spur gear stage of the powershift transmission and is connected in a rotationally fixed manner to a section of a further spur gear stage of the powershift transmission.Because a section of a powershift element of the at least two powershift elements is connected in a rotationally fixed manner to a section of a spur gear stage of the powershift transmission and is connected in a rotationally fixed manner to a section of a further spur gear stage of the powershift transmission, two different switching states of the powershift transmission can be provided by closing one of the powershift elements, namely, for example, the switching states assigned to one gear and the switching states assigned to another gear, wherein in the switching state assigned to one gear, a spur gear stage can be located in the power flow and in the switching state assigned to the other gear, another spur gear stage can be located in the power flow.

[0029] In one embodiment, the at least three gears comprise four gears. The advantages already described have proven particularly advantageous for a transmission with four gears. Because the at least three gears comprise four gears, a large spread can be provided with small gear steps.

[0030] According to the first aspect of the invention, the at least two powershift elements have three powershift elements. Three powershift elements are particularly advantageous for transmissions with four gears. With the help of three powershift elements, one of the powershift elements can be provided such that it is only closed in the lowest gear, with the other two powershift elements being open in the lowest gear. In the higher gears following the lowest gear, one of the other two powershift elements can then be closed, while the other of the other two powershift elements is open. When the other of the other two powershift elements is closed, one of the other two powershift elements can be open, so that shifting under load is also guaranteed between the higher gears or the remaining gears.

[0031] According to the first aspect of the invention, the powershift transmission additionally has a first shifting element and a second shifting element, wherein the first shifting element and the second shifting element are arranged coaxially on an output shaft and can each be connected to a corresponding spur gear by a common coupling element, such that the output shaft is connected to the corresponding spur gear in a rotationally fixed manner. The first shifting element and the second shifting element each preferably have a frictional connection unit and a form-locking unit and can each be referred to as a synchronizer. Preferably, the frictional connection unit is closed first when closing, so that two components rotating at different speeds are initially set in a rotational movement at the same speed.Preferably, the positive locking unit is then closed, so that a positive connection is established between the two components now rotating at the same speeds. The first switching element and the second switching element can each preferably be switched from a closed state to an open state and from an open state to a closed state, in particular independently of the corresponding other switching element, wherein a switching process comprises an opening or a closing. Because the first switching element and the second switching element are arranged coaxially on the output shaft, the first switching element and the second switching element can each rotationally fixedly couple a corresponding spur gear of two spur gears arranged coaxially on the output shaft to the output shaft.Because the first shifting element and the second shifting element can each be connected to a corresponding spur gear by a common coupling element, so that the output shaft is connected to the corresponding spur gear in a rotationally fixed manner, the number of components of the transmission can be kept to a minimum, enabling a simpler transmission design. Furthermore, the number of shifting operations can be reduced, as the coupling element simultaneously opens the second shifting element when it closes the first shifting element, and opens the first shifting element when it closes the second shifting element. This has the advantage of preventing both shifting elements from being closed at the same time. This helps prevent additional loads on the transmission.

[0032] According to a second aspect of the invention, the stated object is achieved by a method having the features of patent claim 8. The method is provided for shifting a powershift transmission, in particular a transmission according to the first aspect of the invention. The method comprises the following steps: closing one powershift element of at least two powershift elements so that a shifting state is established that is associated with a lowest gear or a highest gear of at least three gears, and opening one powershift element so that shifting states can be established that are associated with the remaining gears of the at least three gears, wherein one powershift element of the at least two powershift elements is open in the shifting states that are associated with the remaining gears of the at least three gears. The powershift transmission according to the first aspect of the invention can be shifted using the method.However, the method is not limited to shifting the transmission according to the first aspect of the invention. Rather, other transmissions can also be shifted using the method.

[0033] Using this method, if the lowest gear is affected, those transmission components can be designed to be mechanically robust that are only in the power flow when the powershift transmission is in the shift state associated with the lowest gear, and if the highest gear is affected, those transmission components can be designed to be mechanically less robust that are only in the power flow when the powershift transmission is in the shift state associated with the highest gear. This mechanically more or less robust transmission design allows the other components that are in the power flow when the shift states associated with the other gears are present to be dimensioned accordingly to suit the corresponding mechanical loads present.In the event that the lowest gear is affected, the other components of the transmission can be designed to be less mechanically robust, and in the event that the highest gear is affected, the other components of the transmission can be designed to be more mechanically robust.Thus, with the aid of the method in the powershift transmission, the components which are exposed to high torques can be designed to be particularly mechanically robust and the components which are exposed to lower torques can be designed to be less robust, so that an overall weight-saving and particularly compact transmission can be provided in which, in particular, the components which are exposed to lower torques can have low moments of inertia, whereby a change in the angular velocity of these components is simplified and thus the components can adapt their angular velocity particularly quickly during a gear shift, which in turn keeps the time period for a gear shift short.

[0034] In one embodiment, the method comprises the following steps: closing one powershift element of the at least two powershift elements so that the switching state associated with the lowest gear of the at least three gears is established, and opening one powershift element so that the switching states associated with the remaining gears of the at least three gears can be established, wherein one powershift element of the at least two powershift elements is open in the switching states associated with the remaining gears of the at least three gears. With the aid of the method, the one powershift element is preferably only in the lowest gear in the power flow and not in the remaining gears.Because one powershift element of the at least two powershift elements is closed in the switching state that is assigned to a lowest gear of the at least three gears and is open in the switching states that are assigned to the remaining gears of the at least three gears, the method can be used to design one powershift element and those components that are in the power flow when the powershift transmission is in the switching state that is assigned to the lowest gear to be mechanically robust.The remaining components of the powershift transmission, which are in the power flow when the powershift transmission is in the shift states assigned to the remaining gears of at least three gears and are not in the power flow when the powershift transmission is in the shift state assigned to the lowest gear, can be designed to be correspondingly less mechanically robust, allowing the powershift transmission to be designed to be weight-saving and particularly compact overall. Furthermore, using the method, the remaining components can be designed to have particularly low moments of inertia, allowing the time span for a shifting operation in which these remaining components must change their angular velocity to be kept short.In particular, the method can be used to provide the transmission for components located in a third gear of four gears in the power flow with a low moment of inertia compared to the prior art, thereby simplifying a change in the angular velocity of these components.

[0035] In one embodiment, the method comprises the following steps: closing one of the at least two powershift elements so that the switching state associated with the highest gear of the at least three gears is established, and opening one of the powershift elements so that the switching states associated with the remaining gears of the at least three gears can be established, wherein one of the at least two powershift elements is open in the switching states associated with the remaining gears of the at least three gears. Preferably, with the aid of the method, one of the powershift elements is only in the power flow in the highest gear and not in the remaining gears.Because the method closes one powershift element of the at least two powershift elements in the shift state associated with the highest gear of the at least three gears and opens it in the shift states associated with the remaining gears of the at least three gears, the method allows the one powershift element and those components that are in the power flow when the powershift transmission is in the shift state associated with the highest gear to be made mechanically less robust.The remaining components of the powershift transmission, which are in the power flow when the powershift transmission is in the shift states assigned to the other gears of the at least three gears and are not in the power flow when the powershift transmission is in the shift state assigned to the highest gear, can be designed to be correspondingly more mechanically robust using the method, whereby the powershift transmission as a whole can be designed to be weight-saving and particularly compact. Furthermore, using the method, the one powershift element and those components which are in the power flow when the powershift transmission is in the shift state assigned to the highest gear can be designed such that they have particularly low moments of inertia, whereby the time span for a shifting operation in which these remaining components have to change their angular velocity can be kept short.In particular, the transmission for components located in the power flow in a second gear of four gears can be designed to be more mechanically robust than the state of the art, so that greater torques can be transmitted by these components.

[0036] The features, technical effects and / or advantages described in connection with the powershift transmission according to the first aspect of the invention also apply at least analogously to the method according to the second aspect of the invention, so that a corresponding repetition is omitted at this point.

[0037] Further features, advantages, and possible applications of the present invention will become apparent from the following description of the exemplary embodiments and the figures. All described and / or illustrated features, individually and in any combination, constitute the subject matter of the invention, regardless of their composition in the individual claims or their references. In the figures, the same reference numerals continue to represent the same or similar objects. Fig. 1 shows a schematic representation of an embodiment of a load-shiftable transmission according to the invention, Fig. 2 shows an example shift diagram of the powershift transmission in Fig. 1, Fig. 3 to 6 show schematic representations of the embodiment of the load-shiftable transmission in Fig. 1 in different switching states, and Fig. Figure 7 shows a schematic representation of an embodiment of a method according to the invention, in particular for switching the Fig. 1 and 3 to 6 shown powershift transmission.

[0038] Fig. 1 shows a schematic representation of an embodiment of a powershift transmission 1 according to the invention. The transmission 1 is powershiftable, so that the gear ratio of the transmission 1 can be changed under load, i.e. while driving, without interrupting the torque. The transmission 1 has an input shaft 3, a first shaft 5, a second shaft 7, an output shaft 9, a first powershift element 11, a second powershift element 13, a third powershift element 15, a first shift shaft 17, a second shift shaft 19, and a third shift shaft 21. The transmission 1 therefore has at least two powershift elements 11, 13, 15, namely the first powershift element 11, the second powershift element 13, and the third powershift element 15. In other words, in the illustrated embodiment of the powershift transmission 1, the at least two powershift elements 11, 13, 15 have three powershift elements.The powershift capability of the transmission 1 is ensured by means of the at least two powershift elements 11, 13, 15. The first shift shaft 17 is a hollow shaft assigned to the first powershift element 11, the second shift shaft 19 is a hollow shaft assigned to the second powershift element 13, and the third shift shaft 21 is a hollow shaft assigned to the third powershift element 15.

[0039] The transmission 1 is intended for a motor vehicle, such as an agricultural machine, in particular a tractor, and in an installed state forms a section of a power drive train of the motor vehicle. For this purpose, the input shaft 3 is coupled to a prime mover, preferably an engine. In particular in the case of an agricultural machine, it can be provided that a further transmission unit, such as a splitter transmission unit, is arranged between the prime mover and the transmission 1, viewed in the direction of power flow. A splitter transmission unit can condense the gear sequence of the transmission 1 by dividing the gears of the transmission 1 by small step increments of the splitter transmission unit, thereby increasing the total number of representable gears. In the installed state, the output shaft 9 is coupled to a downstream differential gear, via which the tires of the motor vehicle can be driven.

[0040] The first powershift element 11, the second powershift element 13, and the third powershift element 15 can be designed as a wet-running or dry-running friction shift element. The powershift elements 11, 13, 15 can each be switched independently of one another from a closed state to an open state and from an open state to a closed state, with a switching operation comprising either an opening or a closing.

[0041] In the closed state, the first load switching element 11 provides a rotationally fixed connection between the first shaft 5 and the first switching shaft 17. This rotationally fixed connection ensures a power flow or a torque transmission between the first shaft 5 and the first switching shaft 17. In the open state, the first load switching element 11 does not provide a rotationally fixed connection between the first shaft 5 and the first switching shaft 17, so that there is no power flow or torque transmission between the first shaft 5 and the first switching shaft 17.

[0042] In the closed state, the second load switching element 13 ensures a rotationally fixed connection between the second shaft 7 and the second switching shaft 19. This rotationally fixed connection ensures a power flow or a torque transmission between the second shaft 7 and the second switching shaft 19. In the open state, the second load switching element 13 does not provide a rotationally fixed connection between the second shaft 7 and the second switching shaft 19, so that there is no power flow or torque transmission between the second shaft 7 and the second switching shaft 19.

[0043] In the closed state, the third load switching element 15 provides a rotationally fixed connection between the second shaft 7 and the third switching shaft 21. This rotationally fixed connection ensures a power flow or a torque transmission between the second shaft 7 and the third switching shaft 21. In the open state, the third load switching element 15 does not provide a rotationally fixed connection between the second shaft 7 and the third switching shaft 21, so that there is no power flow or torque transmission between the second shaft 7 and the third switching shaft 21.

[0044] Furthermore, the transmission 1 has a first spur gear stage 23, a second spur gear stage 25, a third spur gear stage 27, a fourth spur gear stage 29, a fifth spur gear stage 31, and a sixth spur gear stage 33. The first spur gear stage 23 has a first spur gear 35 and a second spur gear 37 meshing with the first spur gear 35. The first spur gear 35 is connected in a rotationally fixed manner to the input shaft 3, so that a torque can be transmitted from the input shaft 3 to the first spur gear 35. The second spur gear 37 is connected in a rotationally fixed manner to the first shaft 5, so that a torque can be transmitted from the second spur gear 37 to the first shaft 5. With the help of the first spur gear stage 23, a coupling of the input shaft 3 with the first shaft 5 is ensured, so that, viewed in the direction of power flow from the input shaft 3 to the output shaft 9, a rotational movement of the input shaft 3 causes a rotational movement of the first shaft 5.

[0045] The second spur gear stage 25 has a third spur gear 39 and a fourth spur gear 41 meshing with the third spur gear 39. The third spur gear 39 is connected in a rotationally fixed manner to the first selector shaft 17, so that a torque can be transmitted from the first selector shaft 17 to the third spur gear 39. The fourth spur gear 41 is rotatably mounted on the output shaft 9 and can be rotationally fixedly coupled to it, so that a torque can then be transmitted from the fourth spur gear 41 to the output shaft 9. With the help of the second spur gear stage 25, a coupling of the first selector shaft 17 to the output shaft 9 can be provided, so that, viewed in the direction of power flow from the input shaft 3 to the output shaft 9, a rotational movement of the first selector shaft 17 can bring about a rotational movement of the output shaft 9.

[0046] The third spur gear stage 27 has a fifth spur gear 43 and a sixth spur gear 45 meshing with the fifth spur gear 43. The fifth spur gear 43 is connected in a rotationally fixed manner to the input shaft 3 so that torque can be transmitted from the input shaft 3 to the fifth spur gear 43. The sixth spur gear 45 is connected in a rotationally fixed manner to the second shaft 7 so that torque can be transmitted from the sixth spur gear 45 to the second shaft 7. The third spur gear stage 27 thus ensures a coupling of the input shaft 3 to the second shaft 7 so that, viewed in the direction of power flow from the input shaft 3 to the output shaft 9, a rotational movement of the input shaft 3 causes a rotational movement of the second shaft 7. The fourth spur gear stage 29 has a seventh spur gear 47 and an eighth spur gear 49 meshing with the seventh spur gear 47.The seventh spur gear 47 is connected in a rotationally fixed manner to the third selector shaft 21, so that a torque can be transmitted from the third selector shaft 21 to the seventh spur gear 47. The eighth spur gear 49 is connected in a rotationally fixed manner to the output shaft 9, so that a torque can be transmitted from the eighth spur gear 49 to the output shaft 9. With the help of the fourth spur gear stage 29, a coupling of the third selector shaft 21 to the output shaft 9 is ensured, so that in the direction of power flow from the input shaft 3 to the output shaft 9, a rotational movement of the third selector shaft 21 causes a rotational movement of the output shaft 9.

[0047] The fifth spur gear stage 31 has a ninth spur gear 51 and the fourth spur gear 41 meshing with the ninth spur gear 51. The fourth spur gear 41 is thus both a spur gear of the second spur gear stage 25 and a spur gear of the fifth spur gear stage 31. The ninth spur gear 51 is connected in a rotationally fixed manner to the second selector shaft 19, so that a torque can be transmitted from the second selector shaft 19 to the ninth spur gear 51. As already described, the fourth spur gear 41 is rotatably mounted on the output shaft 9 and can be coupled thereto in a rotationally fixed manner, so that a torque can then be transmitted from the fourth spur gear 41 to the output shaft 9.With the aid of the fifth spur gear stage 31, a coupling of the second selector shaft 19 to the output shaft 9 can be provided, so that, viewed in the direction of force flow from the input shaft 3 to the output shaft 9, a rotational movement of the second selector shaft 19 can cause a rotational movement of the output shaft 9.

[0048] The sixth spur gear stage 33 has a tenth spur gear 53 and an eleventh spur gear 55 meshing with the tenth spur gear 53. The tenth spur gear 53 is connected in a rotationally fixed manner to the second selector shaft 19, so that a torque can be transmitted from the second selector shaft 19 to the tenth spur gear 53. The eleventh spur gear 55 is rotatably mounted on the output shaft 9 and can be rotationally fixedly coupled thereto, so that a torque can then be transmitted from the eleventh spur gear 55 to the output shaft 9. With the help of the sixth spur gear stage 33, a coupling of the second selector shaft 19 to the output shaft 9 can be provided, so that, viewed in the direction of power flow from the input shaft 3 to the output shaft 9, a rotational movement of the second selector shaft 19 can cause a rotational movement of the output shaft 9.

[0049] Furthermore, the transmission 1 has a first shifting element 57 and a second shifting element 59. The first shifting element 57 and the second shifting element 59 each preferably have a frictional engagement unit and a positive engagement unit, and can each be referred to as a synchronizer. During engagement, the frictional engagement unit is first engaged, so that two components rotating at different speeds are initially set in rotation at the same speed. The positive engagement unit is then closed, so that a positive engagement is established between the two components now rotating at the same speed.The first switching element 57 and the second switching element 59 can each be switched, in particular independently of the corresponding other switching element, from a closed state to an open state and from an open state to a closed state, wherein a switching operation comprises an opening or a closing.

[0050] In the closed state, the first switching element 57 ensures a rotationally fixed connection between the fourth spur gear 41 and the output shaft 9. This rotationally fixed connection ensures a power flow or torque transmission between the fourth spur gear 41 and the output shaft 9. In the open state, the first switching element 57 does not provide a rotationally fixed connection between the fourth spur gear 41 and the output shaft 9, so that there is no power flow or torque transmission between the fourth spur gear 41 and the output shaft 9. In the closed state of the first switching element 57, the first switching shaft 17 is coupled to the output shaft 9 via the second spur gear stage 25 such that a rotary movement can be transmitted from the first switching shaft 17 to the output shaft 9.Furthermore, when the first shifting element 57 is in the closed state, the second shifting shaft 19 is coupled to the output shaft 9 via the fifth spur gear stage 31 such that a rotary movement can be transmitted from the second shifting shaft 19 to the output shaft 9. In order to shift the first shifting element 57, which can also be referred to as carrying out a shifting operation on the first shifting element 57, the first shifting element 57 has a coupling element 61 in the form of a sliding sleeve, which can be moved from an open position to a closed position and from the closed position to the open position via an actuating actuator, the open position corresponding to the open state of the first shifting element 57 and the closed position corresponding to the closed state of the first shifting element 57.

[0051] In its closed state, the second switching element 59 connects the eleventh spur gear 55 in a rotationally fixed manner to the output shaft 9. This rotationally fixed connection ensures a power flow or a torque transmission between the eleventh spur gear 55 and the output shaft 9. In the open state, the second switching element 59 does not provide a rotationally fixed connection between the eleventh spur gear 55 and the output shaft 9, so that there is no power flow or torque transmission between the eleventh spur gear 55 and the output shaft 9. In the closed state of the second switching element 59, the second switching shaft 19 is coupled to the output shaft 9 via the sixth spur gear stage 33 such that a rotary movement can be transmitted from the second switching shaft 19 to the output shaft 9.In order to switch the second switching element 59, which can also be referred to as carrying out a switching operation on the second switching element 59, the second switching element 59 also has a coupling element 61 in the form of a sliding sleeve, which can be moved via the actuating actuator from an open position to a closed position and from the closed position to the open position, wherein the open position corresponds to the open state of the second switching element 59 and the closed position corresponds to the closed state of the second switching element 59.

[0052] In the illustrated embodiment, the first switching element 57 and the second switching element 59 are arranged coaxially on the output shaft 9, so that the first switching element 57 and the second switching element 59 can each couple a corresponding spur gear of two spur gears arranged coaxially on the output shaft 9 to the output shaft 9 in a rotationally fixed manner.

[0053] In the present exemplary embodiment, the first switching element 57 and the second switching element 59 have the same coupling element 61, which can also be referred to as a common coupling element 61, and the same actuating actuator, wherein the coupling element 61 and the actuating actuator are designed such that when the first switching element 57 is closed, the second switching element 59 is open, and when the second switching element 59 is closed, the first switching element 57 is open. The coupling element 61 brings about either the closed state of the first switching element 57 or the closed state of the second switching element 59. In a neutral position of the coupling element 61, both the first switching element 57 and the second switching element 59 are open. The common coupling element 61 allows the number of components of the transmission 1 to be kept low, thereby enabling a simpler design of the transmission 1.In addition, the number of switching operations is reduced because the coupling element 61 opens the second switching element 59 at the same time that it closes the first switching element 57. This has the advantage of preventing both switching elements 57, 59 from being closed at the same time. This can prevent additional loads on the transmission 1. In the exemplary embodiment shown, the first switching element 57 and the second switching element 59 are arranged coaxially on the output shaft 9 and can each be connected to a corresponding spur gear, namely the fourth spur gear 41 and the eleventh spur gear 55, by a common coupling element 61, so that the output shaft 9 is connected in a rotationally fixed manner to the corresponding spur gear, namely the fourth spur gear 41 or the eleventh spur gear 55.

[0054] In an alternative embodiment, the first shifting element 57 comprises a first coupling element and a first actuating actuator, and the second shifting element 59 comprises a second coupling element and a second actuating actuator. This has the advantage that the first coupling element and the second coupling element can be controlled independently of one another by the first actuating actuator and the second actuating actuator, thereby allowing the shifting states of the transmission 1 to be adjusted more flexibly.

[0055] The actuator of the shift elements 57, 59, via which the coupling element 61 is actuated, is controlled automatically via a transmission control unit of the transmission 1 (not shown here), so that the shift elements 57, 59 are shifted automatically. Likewise, the first powershift element 11, the second powershift element 13, and the third powershift element 15 are also automatically controlled via this transmission control unit.

[0056] Fig. 2 shows an exemplary shift pattern of the powershift transmission 1 in Fig. 1 and Fig. 3 to 6 show schematic representations of the embodiment of the load-shiftable transmission in Fig. 1 in different switching states. With the help of the gearbox 1, four different gear ratios can be set as gears G1 to G4 between the input shaft 3 and the output shaft 9, whereby each of the gears G1 to G4 is assigned a corresponding switching state of the gearbox 1 and the gears G1 to G4 and the corresponding switching states in Fig. 2 are shown in tabular form. The powershift transmission 1 can therefore assume different shift states, wherein each shift state of the shift states is assigned a gear of at least three gears G1, G2, G3, G4, wherein in each shift state of the shift states one powershift element of the at least two powershift elements 11, 13, 15 is closed. In the illustrated embodiment of the powershift transmission, the at least three gears G1, G2, G3, G4 have four gears, namely a first gear G1, a second gear G2, a third gear G3 and a fourth gear G4. For the first powershift element 11, the second powershift element 13 and the third powershift element 15 as well as for the first shift element 57 and the second shift element 59, an x ​​represents a closed state and an o represents an open state. x / o shows that either a closed state or an open state can exist.Each switching state of the transmission 1 is thus defined by closed and open states of the first powershift element 11, the second powershift element 13, the third powershift element 15, the first switching element 57 and the second switching element 59, wherein in the switching state of the third gear G3, depending on the switching state, the first switching element 57 and the second switching element 59 can be either in the closed state or in the open state.The fact that in the shift state of the third gear G3, depending on the shift state, the first shift element 57, the second shift element 59 and the second powershift element 13 can be in either the closed state or the open state ensures that, depending on the gear preselection, i.e. depending on which gear is to be engaged next, the shift elements 57, 59 can assume a closed or open state, so that when changing from gear to a gear to be engaged, the gear change can be carried out by switching the powershift elements 11, 13, 15, namely opening one of the powershift elements 11, 13, 15, in particular the second powershift element 13 or the third powershift element 15, and closing another of the loadshift elements 11, 13, 15, in particular the second loadshift element 13 or the third loadshift element 15.

[0057] The fact that a component of the powershift transmission 1, such as the input shaft 3, the first shaft 5, the second shaft 7, the output shaft 9, one of the powershift elements 11, 13, 15, one of the shift shafts 17, 19, 21, one of the spur gear stages 23, 25, 27, 29, 31, 33, one of the spur gears 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, or one of the shift elements 57, 59, is located in the power flow means in the context of the present invention that when a rotary movement of the input shaft 3 causes a rotary movement of the output shaft 9, the corresponding component is loaded, in particular completely, with a torque. If, for example, a certain power shift element is in the power flow, this power shift element is in the closed state and this power shift element is loaded with a corresponding torque which ensures that the rotational movement of the input shaft 3 causes the rotational movement of the output shaft 9.If a specific powershift element is in the open state, this powershift element is not in the power flow. If, for example, a specific spur gear stage is in the power flow, both spur gears of this spur gear stage are in the power flow and both spur gears are loaded with a corresponding torque, which ensures that the rotational movement of the input shaft 3 causes the rotational movement of the output shaft 9. For example, the first spur gear stage 23 and the second spur gear stage 25 are in the power flow when the first powershift element 11 is closed and the first switching element 57 is closed. The third spur gear stage 27 is in the power flow when either the second powershift element 13 and the first switching element 57, or the second loadshift element 13 and the second switching element 59, or the third loadshift element 15 are closed.The fourth spur gear stage 29 is in the power flow when the third powershift element 15 is closed. The fifth spur gear stage 31 is in the power flow when both the second powershift element 13 and the first shifting element 57 are closed. The sixth spur gear stage 33 is in the power flow when both the second powershift element 13 and the second shifting element 59 are closed.

[0058] A corresponding component is not in the power flow if it is merely driven but no torque is applied to it that ensures that the rotary movement of the input shaft 3 causes the rotary movement of the output shaft 9. For example, the first spur gear stage 23 is not in the power flow if the first powershift element 11 is open. The previously mentioned components can also only be in the power flow in sections. For example, the fourth spur gear 41 can be in the power flow when the second spur gear stage 25 is in the power flow or when the fifth spur gear stage 31 is in the power flow. The fifth spur gear stage 31 is therefore in the power flow in sections when the second spur gear stage 25 is in the power flow and the second spur gear stage 25 is in the power flow in sections when the fifth spur gear stage 31 is in the power flow.

[0059] As in the Fig. 2 and Fig. 3, the switching state of the first gear G1 is such that the first powershift element 11 and the first switching element 57 are each closed and the second and third powershift elements 13, 15 as well as the second switching element 59 are open. Due to this switching state, the power flow proceeds from the input shaft 3 via the first spur gear stage 23 to the first shaft 5 and from there through the closed first powershift element 11 to the first switching shaft 17 and from there via the second spur gear stage 25 and through the closed first switching element 57 to the output shaft 9. The switching state of the first gear G1 is in Fig. 2 and the corresponding power flow guidance or the set power flow is shown in Fig. 3 shown.

[0060] In Fig. 3 shows the power flow from the input shaft 3 to the output shaft 9 of the first gear G1. The first spur gear 35 is smaller than the second spur gear 37, so that the speed of the second spur gear 37 is lower than the speed of the first spur gear 35. If a spur gear is smaller or larger than another spur gear, this is to be understood as a different size, which in this context means that the number of teeth and / or the diameter is different. The fourth spur gear 41 is larger than the third spur gear 39, so that the speed of the fourth spur gear 41 is lower than the speed of the third spur gear 39. In the first gear G1, the speed is therefore reduced from the input shaft 3 to the output shaft 9, whereby the torque from the input shaft 3 to the output shaft 9 is increased, which can also be referred to as a reduction or slow gear ratio.

[0061] As in the Fig. 2 and Fig. 4, the switching state of the second gear G2 is such that the second powershift element 13 and the first switching element 57 are each closed and the first and third powershift elements 11, 15 as well as the second switching element 59 are open. Due to this switching state, the power flow runs from the input shaft 3 via the third spur gear stage 27 to the second shaft 7 and from there through the closed second powershift element 13 to the second switching shaft 19 and from there via the fifth spur gear stage 31 and through the closed first switching element 57 to the output shaft 9. The switching state of the second gear G2 is in Fig. 2 and the corresponding power flow guidance or the set power flow is shown in Fig. 4 shown.

[0062] In Fig. 4 shows the power flow from the input shaft 3 to the output shaft 9 of the second gear G2. The fifth spur gear 43 and the sixth spur gear 45 are the same size or differ only slightly in size, so that the speed of the fifth spur gear 43 and the speed of the sixth spur gear 45 are identical or at least approximately identical. In the context of the present invention, the term "identical size" means that the number of teeth and / or the diameter is identical. The fourth spur gear 41 is larger than the ninth spur gear 51, so that the speed of the fourth spur gear 41 is lower than the speed of the ninth spur gear 51. The speed is also reduced in the second gear G2 from the input shaft 3 to the output shaft 9, but less significantly than in the first gear G1, whereby the torque from the input shaft 3 to the output shaft 9 is increased, but also less significantly than in the first gear G1.

[0063] As in the Fig. 2 and Fig. 5, the switching state of the third gear G3 is such that the third powershift element 15 is closed and the first powershift element 11 and second powershift element 13 are each open. The first switching element 57 and the second switching element 59 can each be either open or closed. Preferably, the first switching element 57 and the second switching element 59 are open in the third gear G3. Due to the switching state of the third gear G3, the power flow runs from the input shaft 3 via the third spur gear stage 27 to the second shaft 7 and from there through the closed third powershift element 15 to the third switching shaft 21 and from there via the fourth spur gear stage 29 to the output shaft 9. The switching state of the third gear G3 is in Fig. 2 and the corresponding power flow guidance or the set power flow is shown in Fig. 5 shown.

[0064] In Fig. 5 shows the power flow from the input shaft 3 to the output shaft 9 of the third gear G3. As already described, the fifth spur gear 43 and the sixth spur gear 45 are the same size or differ only slightly in size, so that the speed of the fifth spur gear 43 and the speed of the sixth spur gear 45 are identical or at least almost identical. The seventh spur gear 47 is slightly smaller than the eighth spur gear 49, so that the speed of the seventh spur gear 47 is greater than the speed of the eighth spur gear 49. The speed is therefore reduced in the third gear G3 from the input shaft 3 to the output shaft 9, but less significantly than in the second gear G2, so that the torque from the input shaft 3 to the output shaft 9 is increased, but also less significantly than in the second gear G2.

[0065] Due to the design of the powershift transmission 1, the second powershift element 13 can be closed in third gear G3, in which case both shifting elements 57, 59 are open. This can be ensured by placing the common coupling element 61 in a neutral position, in which both shifting elements 57, 59 are open. This has the advantage that the mechanical load on the second powershift element 13 can be kept low during a subsequent shift into the second gear G2 or the fourth gear G4.

[0066] As in the Fig. 2 and Fig. 6, the switching state of the fourth gear G4 is such that the second powershift element 13 and the second switching element 59 are each closed and the first powershift element 11, the third powershift element 15 and the first switching element 57 are each open. Due to this switching state, the power flow proceeds from the input shaft 3 via the third spur gear stage 27 to the second shaft 7 and from there through the closed second powershift element 13 to the second switching shaft 19 and from there via the sixth spur gear stage 33 and through the closed second switching element 59 to the output shaft 9. The switching state of the fourth gear G4 is in Fig. 2 and the corresponding power flow guidance or the set power flow is shown in Fig. 6 shown.

[0067] In Fig. 6 shows the power flow from the input shaft 3 to the output shaft 9 of the fourth gear G4. As already described, the fifth spur gear 43 and the sixth spur gear 45 are the same size or differ only slightly in size, so that the speed of the fifth spur gear 43 and the speed of the sixth spur gear 45 are identical or at least almost identical. The tenth spur gear 53 is larger than the eleventh spur gear 55, so that the speed of the tenth spur gear 53 is lower than the speed of the eleventh spur gear 55. In fourth gear G4, the speed is therefore increased from the input shaft 3 to the output shaft 9, whereby the torque from the input shaft 3 to the output shaft 9 is reduced, which can also be referred to as gear shifting.

[0068] A successive shift between the gears G1 to G4 is possible without interruption of traction in that in the currently shifted state of the respective actual gear and before shifting into the following target gear, a pre-selection takes place if necessary by switching one or more of the switching elements 57, 59, ie are either opened or closed, and the gear change is then carried out by switching the power shift elements 11, 13, 15.

[0069] As already described, the speed in first gear G1 is reduced from the input shaft 3 to the output shaft 9, whereby the torque from the input shaft 3 to the output shaft 9 is increased. In particular, compared to the second gear G2, the third gear G3 and the fourth gear G4, the transmission 1 is loaded with greater torque in first gear G1. The powershift transmission 1 shown has the particular advantage over transmissions known from the prior art that one powershift element of the at least two powershift elements 11, 13, 15, namely the first powershift element 11, is closed in the shift state associated with a lowest gear, namely the first gear G1, and is open in the shift states associated with the remaining gears of the at least three gears G1, G2, G3, G4, namely the second gear G2, the third gear G3 and the fourth gear G4.Because the powershift transmission 1 is designed such that one powershift element of the at least two powershift elements 11, 13, 15 is closed in the shift state associated with a lowest gear of the at least three gears G1, G2, G3, G4 and is open in the shift states associated with the remaining gears of the at least three gears G1, G2, G3, G4, those components can be designed to be mechanically robust which are in the power flow when the powershift transmission 1 is in the shift state associated with the lowest gear.The remaining components of the powershift transmission 1, which are in the power flow when the powershift transmission 1 is in the shift states assigned to the remaining gears of the at least three gears G1, G2, G3, G4 and are not in the power flow when the powershift transmission 1 is in the shift state assigned to the lowest gear, can be designed to be correspondingly less mechanically robust, whereby the powershift transmission 1 can be designed to be weight-saving and particularly compact overall. In particular, the transmission 1 for the third gear G3 can thus provide components in the power flow with a low moment of inertia compared to the prior art, which simplifies changing the angular velocity of these components.

[0070] In the illustrated embodiment of the powershift transmission 1, the first powershift element 11 is closed in the shift state assigned to the first gear G1 and open in the shift states assigned to the second gear G2, the third gear G3, and the fourth gear G4. Therefore, the first powershift element 11 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the first gear G1, and in the shift states assigned to the second gear G2, the third gear G3, and the fourth gear G4, the first powershift element 11 is not in the power flow. Therefore, the first powershift element 11 can be adapted to the loads occurring in the first gear G1 and designed to be correspondingly robust.The second powershift element 13 and the third powershift element 15 can be adapted accordingly to the loads occurring in the second gear G2, the third gear G3, and the fourth gear G4, and can thus be dimensioned to be mechanically less robust and weight-saving. In particular, the transmission 1 for the third gear G3 can thus provide components in the power flow with a lower moment of inertia compared to the prior art, thereby simplifying the angular velocity changes of these components.

[0071] In an alternative embodiment, one powershift element of the at least two powershift elements 11, 13, 15 is closed in the shift state associated with a highest gear of the at least three gears G1, G2, G3, G4, and open in the shift states associated with the remaining gears of the at least three gears G1, G2, G3, G4. For example, by appropriately designing the spur gear stages 23, 25, 27, 29, 31, 33, the first powershift element 11 can be closed in the shift state associated with a fourth gear G4 of four gears G1, G2, G3, G4, and open in the shift states associated with the first gear G1, the second gear G2, and the third gear G3.In this case, the first powershift element 11 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the fourth gear G4, and in the shift states assigned to the first gear G1, the second gear G2, and the third gear G3, the first powershift element 11 is not in the power flow. Therefore, the first powershift element 11 can be adapted to the loads occurring in the fourth gear G4 and can be designed to be correspondingly less mechanically robust. This also means that in this alternative embodiment, the powershift transmission 1 can be designed to be weight-saving and particularly compact overall.

[0072] As already described, the transmission 1 has the first spur gear stage 23. The first spur gear stage 23 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the lowest gear, namely the first gear G1. Therefore, the first spur gear stage 23 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the first gear G1, and in the shift states assigned to the second gear G2, the third gear G3, and the fourth gear G4, the first spur gear stage 23 is not in the power flow. Therefore, the first spur gear stage 23 can be adapted to the loads occurring in the first gear G1 and designed accordingly robustly.In particular, the third spur gear stage 27, the fourth spur gear stage 29, the fifth spur gear stage 31, and the sixth spur gear stage 33 can be adapted, at least in sections, to the loads occurring in the second gear G2, the third gear G3, and the fourth gear G4, and thus be dimensioned to be less mechanically robust and weight-saving. In particular, the transmission 1 for the third gear G3 can thus provide components in the power flow with a lower moment of inertia compared to the prior art, thereby simplifying the angular velocity changes of these components.

[0073] As already described, the transmission 1 has the first shaft 5. The first shaft 5 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the lowest gear, namely the first gear G1. Therefore, the first shaft 5 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the first gear G1, and in the shift states assigned to the second gear G2, the third gear G3, and the fourth gear G4, the first spur gear stage 23 is not in the power flow. Therefore, the first shaft 5 can be adapted to the loads occurring in the first gear G1 and designed accordingly robustly. In particular, the second shaft 7 can be adapted accordingly to the loads occurring in the second gear G2, the third gear G3, and the fourth gear G4 and thus dimensioned to be mechanically less robust and weight-saving.In particular, the transmission 1 for the third gear G3 can thus provide components in the power flow with a low moment of inertia compared to the prior art, thereby simplifying a change in the angular velocity of these components.

[0074] As already described, the transmission 1 has the second spur gear stage 25. The second spur gear stage 25 is only fully in the power flow when the powershift transmission 1 is in the shift state assigned to the lowest gear, namely the first gear G1. In particular, the third spur gear 39 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the first gear G1, since, as already described, the fourth spur gear 41 is both a spur gear of the second spur gear stage 25 and a spur gear of the fifth spur gear stage 31, and the fifth spur gear stage 31 is in the power flow when the powershift transmission 1 is in the shift state assigned to the second gear G2. Therefore, the second spur gear stage 25 is only fully in the power flow.The third spur gear 39 is only in the power flow when the powershift transmission 1 is in the shift state assigned to the first gear G1, and in the shift states assigned to the second gear G2, the third gear G3, and the fourth gear G4, the second spur gear stage 25 is not completely in the power flow because the third spur gear 39 is not in the power flow, but the fourth spur gear 41 is in the power flow because it is a spur gear of the fifth spur gear stage 31. Therefore, the second spur gear stage 25 can be adapted to the loads occurring in the first gear G1 and designed accordingly robustly.In particular, the third spur gear stage 27, the fourth spur gear stage 29, the fifth spur gear stage 31, and the sixth spur gear stage 33 can be adapted, at least in sections, to the loads occurring in the second gear G2, the third gear G3, and the fourth gear G4, and thus be dimensioned to be mechanically less robust and weight-saving. In particular, the transmission 1 for the third gear G3 can thus provide components in the power flow with a lower moment of inertia compared to the prior art, thereby simplifying the angular velocity changes of these components.

[0075] As already described, the transmission 1 has the second powershift element 13. A section of the second powershift element 13 is rotationally fixedly connected to a section of the fifth spur gear stage 31 via the second shift shaft 19 and is also rotationally fixedly connected to a section of the sixth spur gear stage 33 via the second shift shaft 19. In the illustrated embodiment, a section of a powershift element of the at least two powershift elements 11, 13, 15 is rotationally fixedly connected to a section of a spur gear stage of the powershift transmission 1 and is rotationally fixedly connected to a section of another spur gear stage of the powershift transmission 1.Because a section of a powershift element of the at least two powershift elements 11, 13, 15 is connected in a rotationally fixed manner to a section of a spur gear stage of the powershift transmission 1 and is connected in a rotationally fixed manner to a section of a further spur gear stage of the powershift transmission 1, two different switching states of the powershift transmission 1 can be provided by closing this powershift element, wherein in one of the switching states the one spur gear stage is in the power flow and in the other of the switching states the further spur gear stage is in the power flow.Because in the illustrated embodiment a section of the second powershift element 13 is connected in a rotationally fixed manner to a section of the fifth spur gear stage 31 via the second selector shaft 19 and is also connected in a rotationally fixed manner to a section of the sixth spur gear stage 33 via the second selector shaft 19, two different switching states of the powershift transmission 1 can be provided by closing the second powershift element 13, namely the switching states assigned to the second gear G2 and the switching states assigned to the fourth gear G4, wherein in the switching state assigned to the second gear G2 the fourth spur gear stage 29 is in the power flow and in the switching state assigned to the fourth gear G4 the sixth spur gear stage 33 is in the power flow.The fifth spur gear stage 31 can be connected to the output shaft 9 by means of the first switching element 57 and the sixth spur gear stage 33 can be connected to the output shaft 9 by means of the second switching element 59.

[0076] Fig. Figure 7 shows a schematic representation of an embodiment of a method according to the invention, in particular for switching the Fig.1 and 3 to 6. The method comprises a first method step 101 and a second method step 102. In the first method step 101, one of the at least two powershift elements 11, 13, 15, namely the first powershift element 11, is closed, so that the switching state is established which is assigned to the lowest gear of the four gears G1, G2, G3, G4, namely the first gear G1.In the second method step 102, the one powershift element, namely the first powershift element 11, is opened so that the switching states can be established which are assigned to the remaining gears of the at least three gears G1, G2, G3, G4, namely the second gear G2, the third gear G3 and the fourth gear G4, wherein the one powershift element of the at least two powershift elements 11, 13, 15, namely the first powershift element 11, is opened in the switching states which are assigned to the remaining gears of the at least three gears G1, G2, G3, G4, namely the second gear G2, the third gear G3 and the fourth gear G4.

[0077] As already described, in the present embodiment the first powershift element 11 is closed in the shift state assigned to the first gear G1, which is why the first powershift element 11 is closed in the first method step 101. In the shift states assigned to the second gear G2, the third gear G3 or the fourth gear G4, the first powershift element 11 is open, which is why the first powershift element 11 is opened in the second method step 102. The first powershift element 11 is therefore only in the power flow when the powershift transmission 1 is in the shift state assigned to the first gear G1, and in the shift states assigned to the second gear G2, the third gear G3 and the fourth gear G4, the first powershift element 11 is not in the power flow. The first powershift element 11 can therefore be adapted to the loads occurring in the first gear G1 and designed to be correspondingly robust.The second powershift element 13 or the third powershift element 15 or further components of the transmission 1 can be adapted to the loads occurring in the second gear G2, the third gear G3 and the fourth gear G4 and can thus be dimensioned to be mechanically less robust and weight-saving.

[0078] In an alternative embodiment, the method comprises the following steps: closing the one powershift element 11, 13, 15 of the at least two powershift elements 11, 13, 15 so that the switching state is established which is assigned to the highest gear of the at least three gears G1, G2, G3, G4, and opening the one powershift element so that the switching states can be established which are assigned to the remaining gears of the at least three gears G1, G2, G3, G4, wherein the one powershift element of the at least two powershift elements 11, 13, 15 is open in the switching states which are assigned to the remaining gears of the at least three gears G1, G2, G3, G4.As already described in connection with the powershift transmission 1, for example, by appropriately designing the spur gear stages 23, 25, 27, 29, 31, 33, the first powershift element 11 can be closed in the shift state assigned to a fourth gear G4 of four gears G1, G2, G3, G4, which is why the first powershift element 11 is then closed in the first method step 101. In the shift states assigned to the first gear G1, the second gear G2, or the third gear G3, the first powershift element 11 is open, which is why the first powershift element 11 is opened in the second method step 102.The first powershift element 11 is therefore only in the power flow when the powershift transmission 1 is in the shift state assigned to the fourth gear G4, and in the shift states assigned to the first gear G1, the second gear G2, and the third gear G3, the first powershift element 11 is not in the power flow. Therefore, the first powershift element 11 can be adapted to the loads occurring in the fourth gear G4 and designed to be correspondingly less robust. The second powershift element 13 or the third powershift element 15 or other components of the transmission 1 can be adapted to the loads occurring in the first gear G1, the second gear G2, and the third gear G3 and can thus be dimensioned to be mechanically more robust than the first powershift element 11.

[0079] In general, it can therefore be stated that the method ensures that a switching state can be switched in which components of the powershift transmission 1 are in the power flow that are only in the power flow when the lowest gear or the highest gear of the at least three gears G1, G2, G3, G4 is engaged, so that these components can be designed for the mechanical loads present in the lowest gear or the highest gear with which the components are loaded. As already described, in the event that the components are only in the power flow in the switching state assigned to the first gear G1, it can be achieved that only those components that are only in the power flow when the powershift transmission 1 is in the switching state assigned to the first gear G1 need to be designed accordingly.The remaining components that are in the power flow when the powershift transmission 1 is in the shift states associated with the second gear G2, the third gear G3 and the fourth gear G4 and are not in the power flow when the powershift transmission 1 is in the shift state associated with the first gear G1 can be designed to be correspondingly less robust, whereby the transmission 1 can be designed to be lighter and more compact.

[0080] Additionally, it should be noted that "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features described with reference to one of the above embodiments can also be used in combination with other features of other embodiments described above. Reference signs in the claims are not to be considered as limitations. Reference symbol 1 Powershift transmission 3 Input shaft 5 first wave 7 second wave 9 Output shaft 11 first load switching element 13 second load switching element 15 third load switching element 17 first shift shaft 19 second shift shaft 21 third shift shaft 23 first spur gear stage 25 second spur gear stage 27 third spur gear stage 29 fourth spur gear stage 31 fifth spur gear stage 33 sixth spur gear stage 35 first spur gear 37 second spur gear 39 third spur gear 41 fourth spur gear 43 fifth spur gear 45 sixth spur gear 47 seventh spur gear 49 eighth spur gear 51 ninth spur gear 53 tenth spur gear 55 eleventh spur gear 57 first switching element 59 second switching element 61 coupling element 101 first procedural step 102 second procedural step

Claims

[1] Powershift transmission (1) with at least two powershift elements (11, 13, 15), wherein the powershift transmission (1) can assume different switching states, wherein each switching state of the switching states is assigned a gear of at least three gears (G1, G2, G3, G4), wherein in each switching state of the switching states one powershift element of the at least two powershift elements (11, 13, 15) is closed, wherein one power shift element of the at least two power shift elements (11, 13, 15) is closed in the switching state associated with a lowest gear or a highest gear of the at least three gears (G1, G2, G3, G4) and is open in the switching states associated with the remaining gears of the at least three gears (G1, G2, G3, G4), characterized bythat the powershift transmission (1) further comprises a first shaft (5), wherein the first shaft (5) is only in the power flow when the powershift transmission (1) is in the switching state associated with the lowest gear, wherein the at least two load switching elements (11, 13, 15) have three load switching elements, and wherein the powershift transmission (1) further comprises a first shifting element (57) and a second shifting element (59), wherein the first shifting element (57) and the second shifting element (59) are arranged coaxially on an output shaft (9) and can each be connected to a corresponding spur gear by a common coupling element (61), so that the output shaft (9) is connected to the corresponding spur gear in a rotationally fixed manner. [2] Powershift transmission (1) according to the preceding claim, wherein one powershift element of the at least two powershift elements (11, 13, 15) is closed in the shift state associated with the lowest gear of the at least three gears (G1, G2, G3, G4) and is open in the shift states associated with the remaining gears of the at least three gears (G1, G2, G3, G4). [3] Powershift transmission (1) according to claim 1, wherein one powershift element of the at least two powershift elements (11, 13, 15) is closed in the shift state associated with the highest gear of the at least three gears (G1, G2, G3, G4) and is open in the shift states associated with the remaining gears of the at least three gears (G1, G2, G3, G4). [4] Powershift transmission (1) according to one of the preceding claims, which further comprises a first spur gear stage (23), wherein the first spur gear stage (23) is only in the power flow when the powershift transmission (1) is in the shift state associated with the lowest gear. [5] Powershift transmission (1) according to claim 4, which further comprises a second spur gear stage (25), wherein the second spur gear stage (25) is only completely in the power flow when the powershift transmission (1) is in the shift state associated with the lowest gear. [6] Powershift transmission (1) according to one of the preceding claims, wherein a portion of a powershift element of the at least two powershift elements (11, 13, 15) is connected in a rotationally fixed manner to a portion of a spur gear stage of the powershift transmission (1) and is connected in a rotationally fixed manner to a portion of a further spur gear stage of the powershift transmission (1). [7] Powershift transmission (1) according to one of the preceding claims, wherein the at least three gears (G1, G2, G3, G4) have four gears. [8] Method for shifting a powershift transmission (1) according to one of the preceding claims, wherein the method comprises the following steps: closing one powershift element of at least two powershift elements (11, 13, 15) so that a shifting state is established which is associated with a lowest gear or a highest gear of at least three gears (G1, G2, G3, G4), and opening the one powershift element so that shifting states can be established which are associated with the remaining gears of the at least three gears (G1, G2, G3, G4), wherein the one powershift element of the at least two powershift elements (11, 13, 15) is open in the shifting states which are associated with the remaining gears of the at least three gears (G1, G2, G3, G4). [9] Method according to the preceding claim, wherein the method comprises the following steps: Closing one of the at least two power shift elements (11, 13, 15) so that the switching state is established which is assigned to the lowest gear of the at least three gears (G1, G2, G3, G4), and Opening the one power shift element so that the switching states can be established which are assigned to the remaining gears of the at least three gears (G1, G2, G3, G4), wherein the one power shift element of the at least two power shift elements (11, 13, 15) is open in the switching states which are assigned to the remaining gears of the at least three gears (G1, G2, G3, G4). [10] Method according to claim 8, wherein the method comprises the following steps: closing the one power shift element (11, 13, 15) of the at least two power shift elements (11, 13, 15) so that the switching state is established which is assigned to the highest gear of the at least three gears (G1, G2, G3, G4), and opening the one power shift element so that the switching states can be established which are assigned to the remaining gears of the at least three gears (G1, G2, G3, G4), wherein the one power shift element of the at least two power shift elements (11, 13, 15) is open in the switching states which are assigned to the remaining gears of the at least three gears (G1, G2, G3, G4).

Images