Method for heating transmissions

Abstract

A method for heating a transmission (3) having a torque converter (11), wherein different gears (R1, R2, R3, V1, V2, V3) can be engaged by selectively manipulating clutches (K1, K2, K3, KR, KV), wherein the transmission (3) is locked on the output side, thereby fixing the turbine shaft (12) of the torque converter (11) during the introduction of drive power into the transmission (3) by drive element (2), characterized in that the locking is achieved by manipulating clutches (K1, K2, K3, KR, KV) such that two different gears (R1, R2, R3, V1, V2, V3) in one direction of travel are engaged simultaneously.

Description

Technical Field

[0001] This invention relates to a method for effectively heating a transmission and the transmission fluid contained therein. The transmission can be, for example, an automatic / power-shift transmission, a dual-clutch transmission, an automated shift transmission (e.g., with an intermediate shaft structure), or a (hydrostatic mechanical) power-split transmission (CVT). This method is primarily used for transmissions in working machinery, but can also be applied to transmissions in other vehicles. Background Technology

[0002] At lower temperatures, the viscosity of the transmission fluid can significantly reduce shifting comfort and efficiency. Furthermore, it can be difficult to supply sufficient amounts of transmission fluid where lubrication is required, such as in bearings, shift elements, and gears. Uneven temperature distribution within the transmission is also detrimental to component wear and lifespan.

[0003] To overcome this, a preheating function is known to be provided, particularly for heating the transmission after a cold start. For example, US 2016 / 0084371A1 discloses a preheating function for an automatic transmission or the transmission fluid contained therein, incorporating a method for checking fluid levels. Here, the engine speed is increased, and the turbine shaft on the output side of the transmission's torque converter is rotatably fixed relative to the transmission housing by engaging the clutch and brake. Summary of the Invention

[0004] The objective of this invention is to provide an improved method for heating a transmission and the transmission fluid contained therein.

[0005] This task is solved using the method according to the invention. Here, the clutch of the transmission with a torque converter is selectively operated to engage different gears. Engaged gears are understood to adjust the transmission ratio between the input and output ends of the transmission. Within the scope of this method, the transmission is locked on the output side. This means that the turbine shaft of the torque converter is fixed during the introduction of drive power into the transmission via the drive element. Consequently, power loss is generated in the torque converter as heat. The drive element can be implemented as an internal combustion engine or an electric motor. Hybrid embodiments are also conceivable, wherein the drive power is generated by an internal combustion engine and / or an electric motor. According to the invention, the transmission is locked in such a way that two different gears in one direction of travel are engaged simultaneously. Depending on the embodiment of the transmission, the transmission can have multiple forward and reverse gears. Therefore, the method can be performed identically whether different forward gears or different reverse gears are engaged simultaneously.

[0006] In the first step of this method, the relevant clutch is operated to engage two different gears. Here, the clutch can be implemented as a form-locking or friction-locking shifting element. In particular, these shifting elements are operated hydraulically or mechanically (electromechanically). In the case of hydraulic operation, the clutch is pressure-loaded for operation, thereby closing the clutch and transmitting torque or rotational motion. For example, first and second gears can be engaged. Alternatively, in addition to locking the output side by means of the clutch, the vehicle's service brake and / or parking brake and / or the transmission's parking lock can also be operated. However, locking achieved by engaging two different gears can support higher input torque, thereby introducing higher drive power, generating higher power loss, and thus achieving higher heat input. Therefore, this results in faster and more efficient heating of the transmission. The clutch is typically operated by a transmission control unit, and thus this method can also be implemented by this control unit.

[0007] In the second step, the driving direction clutch is operated. Typically, a transmission has two driving direction clutches, one for forward travel and the other for reverse travel. This allows for the generation of the same number of forward and reverse gears. After operating the clutches as described above, the third step increases the speed of the drive element, particularly from idle speed to warm-up speed.

[0008] After maintaining the adjusted speed for a limited duration, the speed is reduced again in the fourth step, and then the previously engaged driving direction clutch is disengaged in the fifth step. The duration of the speed increase of the drive element can be preset in a fixed manner, or it can be determined individually according to other parameters. In particular, the duration of the speed increase must be limited to avoid overheating. In the sixth step, a flushing process is initiated to flush the disengaged clutch and circulate the transmission fluid. This results in a more uniform heat distribution.

[0009] At the end of the process, temperature can be measured directly or indirectly using sensors to check whether the predetermined target temperature has been reached or even exceeded. The heating method then terminates. If the target temperature has not been reached, steps two through six are repeated. Here, the sequence of steps two through six corresponds to a cycle.

[0010] In the improved scheme, the cycle duration may vary, especially decreasing as the number of cycles increases. The cycle duration can also be determined based on the known temperature of the transmission. The duration may also decrease as the temperature increases. However, a fixed number of cycles can also be preset, or the number of cycles can be determined from the temperature at the start of the method.

[0011] As the target temperature is reached at the end of the relevant cycle, in the seventh step, the relevant driving direction clutch is also disengaged, and the method terminates.

[0012] Advantageously, two adjacent gears are engaged simultaneously for locking on the output side of the transmission. Here, for example, these gears are the first and second gears. However, any other combination is conceivable. Engaging adjacent gears has the advantage that similarly high torque can be supported or transmitted. The further apart the engaged gears are (e.g., first and third gears), the greater the imbalance in the supported torque.

[0013] Optionally, monitoring of the output speed is configured. This is used to ensure that the vehicle does not move in an unacceptable manner during the method used to heat the transmission. Therefore, no speed is allowed on the output side. Once an unacceptable speed is detected, the method is interrupted and the transmission is shifted to a safe state. For this purpose, the controlled driving direction clutch and / or all clutches can be disengaged.

[0014] This method can be enabled either manually by the operator or automatically. For automatic activation, environmental and / or transmission parameters (temperature) can be considered. Alternatively, it can be set to prompt the operator to activate the method upon vehicle startup.

[0015] According to another aspect of the invention, a vehicle having a drive element and a transmission having a clutch and a torque converter is provided. The transmission also has control devices, such as a transmission control unit. The control devices are adapted and configured for implementing the method according to the invention. The control devices can be implemented separately, integrated into a transmission control unit, an engine control unit, or a higher-level control unit. Attached Figure Description

[0016] The invention is described in detail with reference to the following figures. Herein:

[0017] Figure 1 A flowchart over time is shown when implementing the method;

[0018] Figure 2 A schematic diagram of the transmission is shown;

[0019] Figure 3 An embodiment of a vehicle having a control device for implementing the method is shown;

[0020] Figure 4 It shows the method of manipulation based on Figure 2 The shift matrix of the transmission;

[0021] Figure 5 A schematic diagram of the method steps is shown. Detailed Implementation

[0022] Figure 1 The process of heating the transmission 3 according to the invention is illustrated in a very simplified, non-scaled diagram over time. Time t is plotted on the horizontal axis, while rotational speed n and pressure p are shown on the vertical axis. Furthermore, the change in pressure pK12 is shown by dashed lines, corresponding to the operating pressures of the first and second clutches K1 and K2. These clutches are simultaneously engaged and engaged at the same pressure pK12. The change in rotational speed nA of the drive element 2 is shown by dashed lines. The change in pressure pKV is illustrated by solid lines, corresponding to the operating pressure of the forward (driving direction) clutch KV. In the embodiment of the method shown here, the reverse (driving direction) clutch KR remains in an unengaged state, which can operate in the same manner as the forward clutch KV to implement the method. According to the invention, the transmission 3 is now locked on the output side by engaging clutches K1, K2, and K3, causing targeted power losses in the torque converter 11 in the form of heat, which heat the transmission 3.

[0023] At time t0, drive element 2 is in a deactivated state, therefore, the rotational speed nA has a value of n0. At time t1, drive element 2 is activated, and subsequently (jumping) to the rotational speed n1. This corresponds, for example, to the idle speed of drive element 2, provided that the drive element is implemented as an internal combustion engine. Until time t2, pressures pKV and pK12 have a pressure p0. Therefore, the first and second clutches K1, K2, and clutch KV are not pressured.

[0024] At time t2, pressure is applied to the first and second clutches K1 and K2, with the pressure increase occurring at a first gradient. At time t3, pressure pK12 reaches a value p1, corresponding to fully engaged clutches K1 and K2. Therefore, maximum torque transmission is possible. As pressure pK12 reaches its value p1, clutch KV is loaded with pressure. Thus, pressure pKV increases. A time offset (not shown) can also be set between reaching pressure pK12 at its value p1 and the start of pressure increase with respect to pressure pKV, such that this does not occur precisely at the same time point t3. Here, pressure is applied at a second gradient, which may be different from or the same as the first gradient. At time t4, pressure pKV also reaches its value p1. At the same time point or optionally with a time offset (not shown), rotational speed nA increases from its value n1 to its value n2 at time t5. Here, this is performed using a third gradient, which is typically different from the first and second gradients. Until time point t6, the rotational speed nA remains at value n2, and then decreases to value n1 during the interval between time points t6 and t7. This can be done using a negative third gradient or any other arbitrary gradient. At time point t7, the pressure pKV is reduced until it regains a value p0 at time point t8. This can be done using a second gradient or any other arbitrary gradient. Optionally, the time offset can also be set again here. Until time point t9, the rotational speed nA remains at value n1, and the pressure pKV remains at value p0. During this interval, a flushing process occurs to distribute heated transmission fluid in transmission 3 and flush clutches K3, KV, and KR.

[0025] The interval between time points t3 and t9 describes the first cycle I for heating the transmission 3. If the target temperature of the transmission 3 or the transmission fluid has not yet been reached, then the same second cycle II and possibly a third cycle III follow the first cycle I. Here, the pressure pKV increases from time point t9 to time point t10 as it has already done in the first cycle I. At time point t10, the rotational speed nA increases until it reaches time point t11. In the interval between time points t12 and t13, the rotational speed nA decreases, and in the interval from time point t13 to time point t14, the pressure pKV drops again to the value p0. A flushing process then proceeds until time point t15 is reached.

[0026] The third cycle, III, corresponds to the flow of the first and second cycles, I and II. At time t15, the pressure pKV increases, and at time t16, the rotational speed nA increases. Until time t18, the rotational speed nA and the pressure pKV remain constant. During the interval from t19 to t20, before the pressure pKV drops back to the value p0, the rotational speed nA first drops back to the value n1 during the interval from t18 to t19. The third cycle III terminates as the flushing process ends at time t21.

[0027] In the example shown here, the target temperature is reached at the end of the third cycle, III. Since no further cycles I, II, and III are required, the pressure pK12 drops to the value p0 during the interval from t21 to t22. Here, from time point t3 to time point t21, the pressure pK12 remains at a constant value p1. At time point t22, the method ends. Regular operation of vehicle 1 can then begin.

[0028] For example, an increase of 0.8 bar / s can be set for the first and second gradients, so that the rated pressure of p1 = 16 bar is reached after approximately 20 seconds. Furthermore, rotational speeds such as n1 = 800 l / min and n2 = 1500 l / min can be set.

[0029] In an improved embodiment (not shown), the pressure loading of clutch KV can also be configured not only to occur at time point t3, i.e., when the pressure pK12 reaches the value p1, but also at an earlier time point. Specifically, this can occur halfway through the interval between time points t2 and t3. This is because at that time point, the first and second clutches K1 and K2 have already been loaded with pressure sufficient to counteract the torque transmitted by clutch KV.

[0030] When vehicle 1 is equipped with a motor as the drive element 2, the rotational speed n1 can also be the same as the rotational speed n0. In other words, it is not necessary to start or maintain the idle speed. In other respects, this method can be implemented in the same way using this adjustment.

[0031] Figure 2The transmission 3 is illustrated schematically. Rotational motion or torque is introduced from a drive element 2 (not shown) via a drive shaft 4. The transmission 3 currently has a torque converter 11, which is supported on a housing G and uses a turbine shaft 12 to introduce rotational motion into the transmission 3 for gear shifting. Gear Z1 is connected to the turbine shaft 12 in a rotationally inert manner. Gear Z1 meshes with gear Z2, which is supported on a shaft W1 in a rotationally inert manner. Gear Z2 can be connected via a clutch KR to gear Z4, which is rotatably arranged on the shaft W1. Gear Z4 meshes with gear Z5, indicated by the arrow shown by the dashed line. Gear Z5 is arranged on the shaft W2 in a rotationally inert manner. Furthermore, gear Z3 is rotatably arranged on the turbine shaft 12 and also meshes with gear Z5. Gear Z3 can be connected to gear Z1 via a clutch KV. In other words, rotational motion is transmitted to gear Z5 either when clutch KR is actuated or when clutch KV is actuated.

[0032] Gear Z6 is also arranged on shaft W2, but rotatably arranged on shaft W2 compared to gear Z5. Gear Z6 can be connected to gear Z5 via clutch K1. Gear Z7 is rotatably arranged on output shaft 5, and gears Z8 and Z10 are arranged on output shaft 5 with resistance to relative rotation. Gears Z7 and Z8 can be connected to each other via clutch K2. Gear Z7 meshes with gear Z5, while gear Z8 meshes with gear Z6.

[0033] Gear Z7 also meshes with gear Z9, which is mounted on shaft W3 in a way that resists relative rotation. Additionally, gear Z11 is rotatably mounted on shaft W3 and meshes with gear Z10. Gears Z11 and Z9 can be interconnected via clutch K3.

[0034] Gears Z1 to Z11 are typically implemented as spur or helical cylindrical gears. The anti-relative rotation arrangement can be understood as the associated gears Z1, Z2, Z5, Z8, Z9, and Z10 being implemented as fixed gears, and therefore rotating at the same speed in the same direction of rotation as the associated shafts 12, 5, W1, W2, and W3. Conversely, the rotatable arrangement can be understood as the associated gears Z3, Z4, Z6, Z7, and Z11 being implemented as loose gears, thus allowing relative movement between the loose gears and the associated shafts 12, 5, W1, W2, and W3. In other words, the loose gears and the associated shafts 12, 5, W1, W2, and W3 can rotate freely relative to each other. Anti-relative rotation connection between the loose gears and shafts 12, 5, W1, W2, and W3 or the fixed gears can be established by manipulating clutches K1, K2, K3, KV, and KR.

[0035] Figure 3A simplified illustration shows an embodiment of vehicle 1 in which the method according to the invention is implemented. Currently, vehicle 1 is implemented as a working machine, particularly as a wheeled loader. The application of the method according to the invention is not limited to wheeled loaders or working machines; rather, this embodiment is described in more detail here only by way of example.

[0036] Vehicle 1 has a drive element 2 and a transmission 3. The drive element 2 and transmission 3 are interconnected via a drive shaft 4. In other words, the rotational motion or torque of the drive element 2 is introduced into the transmission 3 via the drive shaft 4. Depending on the corresponding gear ratio, the torque or rotational motion of the drive element 2 is amplified or weakened by the transmission 3 and transmitted to the axles 7 and 8 via the output shaft 5. This drives the wheels 6 of the axles 7 and 8. Here, one or more axles 7 and 8 can be driven. In addition, vehicle 1 has an accessory 9, which is currently configured as a lifting frame with a bucket.

[0037] In the embodiment shown here, vehicle 1 has a separate control device 10, which is connected to drive element 2 and transmission 3 in a signal transmission manner. The signal transmission connection is... Figure 3 The diagram is shown with dashed lines. Alternatively, the control device 10 can also be integrated into the transmission 3 or the drive element 2, for example, into a transmission control unit or an engine control unit. The method according to the invention is implemented in the control device 10, and corresponding signals for operating the drive element 2 and the transmission 3 are generated and transmitted. In the same manner, signals, for example, regarding the operating state or parameters that vary depending on the device, can be forwarded from the drive element 2 and / or the transmission 3 to the control device 10 and processed by the control device.

[0038] Figure 4 The shift matrix for operating the transmission 3 is shown. Here, X represents the operated clutches KV, KR, K1, K2, and K3. By alternately operating clutches KV, KR, K1, K2, and K3, the transmission 3 can achieve a total of six different gears V1, V2, V3, R1, R2, and R3. Here, they are correspondingly divided into three forward gears V1, V2, and V3 and three reverse gears R1, R2, and R3. To provide the first forward gear V1, the forward (driving direction) clutch KV and the first clutch K1 are in the operating state. The second forward gear V2 is achieved by operating the forward (driving direction) clutch KV and the second clutch K2. The third forward gear V3 is achieved using the operated forward (driving direction) clutch KV and the third clutch K3.

[0039] Three reverse gears, R1, R2, and R3, can be generated in the same way. Similar to forward gears V1, V2, and V3, the reverse (driving direction) clutch KR is operated using the corresponding clutches K1, K2, and K3. Therefore, in order to generate gears V1, V2, V3, R1, R2, and R3, the (driving direction) clutches KV and KR and the (gear) clutches K1, K2, and K3 are simultaneously in operation.

[0040] Figure 5 A schematic diagram of steps S1, S2, S3, S4, S5, S6, and S7 of the method according to the invention is shown. Here, in the first step S1, clutches K1, K2, and K3 are operated to adjust to two different gears R1, R2, R3, V1, V2, and V3. In the second step S2, the travel direction clutches KR and KV, such as clutch KV, are operated. In the third step S3, the rotational speed nA of the drive element 2 is increased until it is decreased again in the fourth step S4. In the fifth step S5, the travel direction clutches KR and KV, which were operated in the second step S2, are disengaged, and subsequently, the flushing process is initiated in the sixth step S6. Steps S2 to S6 represent... Figure 1 The publicly disclosed cycles I, II, and III are then repeated. Steps S2 through S6 are repeated cyclically until the target temperature of the transmission (3) is reached. When the target temperature is reached after the relevant cycles I, II, and III have ended, the clutches K1, K2, and K3, which were operated in the first step S1, are disengaged in the seventh step S7. After performing the seventh step S7, the method ends. Regular operation of vehicle 1 can then begin.

[0041] List of reference numerals

[0042] 1 vehicle

[0043] 2. Driving components

[0044] 3. Transmission

[0045] 4 drive shafts

[0046] 5 Output shaft

[0047] 6 wheels

[0048] 7 and 8 axles

[0049] 9. Annex

[0050] 10. Control equipment

[0051] 11 Torque Converter

[0052] G housing

[0053] I, II, III (preheating) cycles

[0054] KR, KV (driving direction) clutch

[0055] K1, K2, K3 (gear positions) clutch

[0056] Rotational speeds of n, n0, n1, and n2

[0057] Rotational speed of nA drive element

[0058] pressures p, p0, p1

[0059] The pressure of pK12 K1 and K2

[0060] pKV KV pressure

[0061] R1, R2, R3 (reverse) gears

[0062] S1-S7 (Method) Steps

[0063] t0-t22 time points

[0064] V1, V2, V3 (forward) gears

[0065] W1-W3 axes

[0066] Z1-Z11 gears

Claims

1. A method for heating a transmission (3) having a torque converter (11), wherein, Different gears (R1, R2, R3, V1, V2, V3) can be engaged by selectively manipulating the clutches (K1, K2, K3, KR, KV), wherein the transmission (3) is locked on the output side, and thus the turbine shaft (12) of the torque converter (11) is fixed while drive power is introduced into the transmission (3) via the drive element (2). The characteristic feature is that the locking is achieved by manipulating the clutches (K1, K2, K3, KR, KV) such that two different gears (R1, R2, R3, V1, V2, V3) in one direction of travel are engaged simultaneously, wherein... - In the first step (S1), operate the clutches (K1, K2, K3) to adjust to two different gears; - In the second step (S2), operate the clutch (KR, KV) to control the direction of travel; - In the third step (S3), the rotational speed (nA) of the drive element (2) is increased; - In the fourth step (S4), the rotational speed (nA) is reduced; - In the fifth step (S5), the clutches (KR, KV) that were operated in the second step (S2) in the direction of travel are disengaged; - In step six (S6), the rinsing process is initiated.

2. The method according to claim 1, characterized in that, Steps two through six (S2, S3, S4, S5, S6) are repeated cyclically until the target temperature of the transmission (3) is reached.

3. The method according to claim 2, characterized in that, When the target temperature is reached, the clutches (K1, K2, K3) that were operated in the first step (S1) are disengaged in the seventh step (S7).

4. The method according to any one of claims 1 to 3, characterized in that, To lock, engage two adjacent gears simultaneously.

5. The method according to any one of claims 1 to 3, characterized in that, The output speed is monitored, and once an unacceptable speed value is detected on the output shaft (5), the transmission (3) is switched to a safe state and the heating process is interrupted.

6. The method according to any one of claims 1 to 3, characterized in that, The method is enabled by manual input and / or automatically.

7. A vehicle (1) having a drive element (2) and a transmission (3), the transmission having clutches (K1, K2, K3, KR, KV) and control devices (10), wherein, The control device (10) is adapted and configured to implement the method according to any one of claims 1 to 6.

Images