JP-2022518421-A5 -

Dates

Publication Date

20221214

Application Date

20200730

Description

When the pump unit receives a command to switch the clutch, it fills the clutch with transmission oil. After filling the clutch, if the pressure exceeds the kiss point, the necessary pressure is formed and the clutch is switched. This pressure is maintained constant until a request to release the clutch is made. In this regard, the kiss point is the operating state in which the clutch discs make contact. In a preferred embodiment, the second safety unit is designed to increase the filling time of the oil pump in order to limit the rotational speed of the motor, in which case the filling time refers to the duration for which a unit connected to the oil pump is filled by the oil pump. To reduce noise in the pump unit, the rotational speed of the motor (210) can be reduced by the oil pump during the clutch engagement phase, to the extent possible depending on the allowable time interval until the clutch is switched. To this end, the motor's rotational speed (n) is adjusted by a maximum speed value (n Lim ) transmitted to the safety unit (220) when the clutch is engaged . When a start signal is received, for example, the motor is started initially without load at the maximum possible rotational speed according to its characteristic curve. Subsequently, if the maximum allowable time interval required until the clutch is switched (also called the clutch engagement phase) is not used, the rotational speed can be limited by the safety unit (220). Thus, the engagement time can be increased to the maximum allowable time (e.g., 200 ms). Thus, the motor's rotational speed (n) can be reduced during the same process. Lowering the rotational speed of the motor (210) reduces noise. Figure 3 shows a diagram of the switching operation of an embodiment of the present invention. The filling process will be explained as an example relating to the switching of a clutch in a vehicle at a set pressure. In the diagram shown in Figure 3, the horizontal axis represents time in milliseconds [ms], and the vertical axis represents the filling amount, oil pressure, and terminal current/battery current I (DC) or motor rotation speed. If a pressure signal is received, for example, by the control unit of the pump unit, clutch charging is initiated by the oil pump. The pressure signal may be interpreted as a command to switch the clutch and receive a set value at the control unit (100). Upon receiving the pressure signal, clutch charging begins, and the charging level in the clutch rises (see the " Charging " graph in Figure 3). Once charging is complete, the charging level in the clutch is maintained at a constant level (approximately 230 ms later in Figure 3). After receiving the pressure signal, the phase current I (rms) and the terminal/battery current I (DC) jump to their respective maximum values. In this case, the maximum value of the phase current or terminal current can be the maximum possible value, or a value set by the user or manufacturer through the safety unit, as described above, to improve the safety and lifespan of the pump unit. After filling is complete, the phase current I (rms) is maintained at a constant value of the target value. Furthermore, after receiving the pressure signal, the rotational speed of the pump unit's motor increases, and this rotational speed is then limited to, for example, approximately 3700 rpm. By limiting the rotational speed during the filling phase, the clutch can be filled within an allowable duration. The allowable duration for clutch filling is approximately 230 ms in the example shown in Figure 3. For example, if the motor rotational speed is to be limited to reduce noise, the filling time by the oil pump can be increased to the maximum allowable duration (e.g., 230 ms), and this filling time represents the duration for the oil pump to fill the unit connected to the oil pump, in this case the clutch connected to the oil pump. Once clutch filling is complete, the motor rotational speed is maintained constant (for example, approximately 1400 rpm). Furthermore, when the clutch is engaged , the necessary pressure is generated after exceeding the clutch's kiss point, which triggers the clutch switching. As shown in Figure 3, the kiss point, i.e., the operating state where the clutch discs make contact, is exceeded approximately 210 ms, and the pressure increases. After the engagement is complete, the pressure is maintained constant until the clutch is released. Furthermore, the torque increases and remains constant even after the filling process is complete.