Dog clutch control system

Abstract

This dog clutch control system comprises: a rotational frequency detection unit (S2, S22) that detects a first rotational frequency of a first engagement member (11), and detects a second rotational frequency of a second engagement member (12); a reaching time prediction unit (S5, S24) that, on the basis of the first rotational frequency and the second rotational frequency, and a time-changing characteristic of a rotational frequency difference when a rotational frequency adjustment is performed to make the rotational frequency difference between the first engagement member and the second engagement member equal to or less than a predetermined value, predicts a reaching time at which the rotational frequency difference when the rotational frequency adjustment is performed reaches the predetermined value; and a phase correction unit (S10, S11, S10-1, S11-1, S29, S30) that performs a phase correction on at least one of the first engagement member and the second engagement member at a time before the reaching time. By performing the phase correction, the phase correction unit brings an engageable time, at which engagement of the first engagement member and the second engagement member is available after the reaching time, closer to the reaching time compared to when the phase correction is not performed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2022-143714, filed on September 9, 2022, the contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a control system for a dog clutch. [Background technology]

[0003] The control device disclosed in Patent Document 1 detects the phase difference between the first and second engagement members after the difference in rotational speed between the first and second engagement members falls below a predetermined value at which they can be engaged.The control device then adjusts the driving state of the electric motor that rotates the first engagement member so that the phase difference is such that the first and second engagement members can be engaged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4029875 Summary of the Invention

[0005] In the above-described conventional technology, the phase of the first engaging member is adjusted so that the phase difference between the first engaging member and the second engaging member is such that the first engaging member and the second engaging member can be engaged after the rotational speed difference between them becomes equal to or less than a predetermined value. Therefore, after the rotational speed difference becomes equal to or less than the predetermined value, engagement must be delayed until the phase difference becomes equal to or less than the predetermined value. This waiting period delays engagement of the dog clutch. Therefore, the responsiveness of the dog clutch from receiving an engagement command to actually engaging the clutch is low. The present disclosure aims to provide a clutch control system that can improve responsiveness.

[0006] According to one aspect of the present disclosure, a dog clutch control system includes: a dog clutch having a first engagement member that rotates about an axis and has a plurality of first gear teeth formed over the entire circumference in the rotational direction when rotating about the axis, and a second engagement member that rotates about the axis in the same direction as the first engagement member and has a plurality of second gear teeth that mesh with the plurality of first gear teeth formed over the entire circumference in the rotational direction; an actuator that switches between an engaged state in which the first engagement member and the second engagement member are engaged with each other by moving at least one of the first engagement member and the second engagement member in an axial direction parallel to the axis, whereby the first gear teeth and the second gear teeth mesh with each other, and a released state in which the first engagement member and the second engagement member are separated; a rotation speed detection unit that detects a first rotation speed of the first engagement member and a second rotation speed of the second engagement member; an arrival time prediction unit that predicts a time when the rotation speed difference will reach or be equal to or less than a predetermined value when the rotation speed adjustment is performed, based on the first rotation speed and the second rotation speed detected by the rotation speed detection unit and the time change characteristics of the rotation speed difference when the rotation speed adjustment is performed to make the rotation speed difference between the first engaging member and the second engaging member equal to or less than a predetermined value; a phase correction unit that performs phase correction on at least one of the first engagement member and the second engagement member at a time before the arrival time, By performing phase correction, the phase correction unit brings the engageable time, at which the first engagement member and the second engagement member are able to engage with each other after the arrival time, closer to the arrival time than when phase correction is not performed.

[0007] According to this, the phase correction unit performs phase correction at a time before the arrival time when the rotation speed difference reaches or is equal to or less than a predetermined value. This phase correction brings the engageable time closer to the arrival time compared to when phase correction is not performed. Therefore, compared to when phase correction is not performed, the time from when the rotation speed difference reaches or is equal to or less than the predetermined value until the engageable state is achieved can be shortened. Therefore, responsiveness can be improved.

[0008] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a configuration of a power transmission system according to a first embodiment. [Figure 2] FIG. 10 is a diagram showing the relationship between gear teeth and the detection range of the phase difference sensor when the first engagement member and the second engagement member rotate in the same rotational direction, there is no difference in rotation speed between them, and their relative phases are in an engageable state. [Figure 3] 3 is a diagram showing time-series data of a sensor signal of a phase difference sensor in the case of FIG. 2. FIG. [Figure 4] FIG. 10 is a diagram showing the relationship between gear teeth and the detection range of the phase difference sensor when the first engagement member and the second engagement member rotate in the same rotational direction, there is no difference in rotational speed between them, and their relative phases are in an inengageable state. [Figure 5] 5 is a diagram showing time-series data of a sensor signal of a phase difference sensor in the case of FIG. 4. FIG. [Figure 6] 10 is a diagram showing the relationship between gear teeth and the detection range of a phase difference sensor when the first engagement member and the second engagement member rotate in the same rotational direction and there is a difference in rotation speed between them. FIG. [Figure 7] 7 is a diagram showing time-series data of a sensor signal of a phase difference sensor in the case of FIG. 6. FIG. [Figure 8] 10 is a diagram illustrating how future timings of engageable states can be predicted from multiple past timings of engageable states based on time-series data of sensor signals from a phase difference sensor. FIG. [Figure 9] 10 is a diagram showing the relationship between gear teeth and the detection range of a phase difference sensor when a first engagement member and a second engagement member are engaged with each other. FIG. [Figure 10] 10 is a diagram showing time-series data of a sensor signal of a phase difference sensor in the case of FIG. 9. FIG. [Figure 11] 5 is a diagram showing a phase correction, a target engagement timing, and an engageable state timing in the first embodiment. FIG. [Figure 12] 4 is a flowchart showing a process executed by an arithmetic and control device in the first embodiment. [Figure 13] 10 is a diagram showing a phase correction, a target engagement timing, and an engageable state timing in a second embodiment. FIG. [Figure 14] FIG. 11 is a diagram illustrating phase correction in the third embodiment. [Figure 15] 10 is a flowchart showing a process executed by an arithmetic and control device in the third embodiment. [Figure 16] FIG. 10 is a diagram illustrating phase correction, target engagement timing, and timing of an engageable state in a comparative example. [Figure 17] 13 is a diagram showing a phase correction, a target engagement timing, and an engageable state timing in a fourth embodiment. FIG. [Figure 18] 10 is a diagram showing time-series data of a sensor signal when the second engagement member is rotating and the first engagement member is stationary. FIG. [Figure 19] 10 is a diagram showing time-series data of a sensor signal when the second engagement member is rotating and the first engagement member is stationary. FIG. [Figure 20] FIG. 10 is a diagram showing a state in which the second engagement member is rotating and the first engagement member is stationary, and the first gear tooth of the first engagement member on the stationary side is within the detection range of the phase difference sensor. [Figure 21] FIG. 10 is a diagram showing a state in which the second engagement member is rotating and the first engagement member is stopped, and the first gear tooth of the first engagement member on the stopped side is not within the detection range of the phase difference sensor. [Figure 22] 10 is a flowchart showing a process executed by an arithmetic and control device in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0011] (First embodiment) The dog clutch control system of the present disclosure is applied to a power transmission system 1 shown in Fig. 1. The power transmission system 1 is mounted on a vehicle and transmits or cuts off the power of an electric motor 30 to drive wheels. Specifically, the power transmission system 1 includes a dog clutch 10, an actuator 20, the electric motor 30, a phase difference sensor 40, and a calculation and control device 50.

[0012] The dog clutch 10 has a first engagement member 11 and a second engagement member 12. The first engagement member 11 rotates around an axis AL1. The direction parallel to the axis AL1 is the axial direction DR1. At the end of the first engagement member 11 in the axial direction DR1, a plurality of first gear teeth 13 are formed over the entire circumference in the rotational direction when the first engagement member 11 rotates around the axis AL1. The plurality of first gear teeth 13 are each spaced apart and form a row. For this reason, the plurality of first gear teeth 13 are also referred to as a row of first gear teeth 13. A first gap 15 exists between adjacent first gear teeth 13 in the rotational direction.

[0013] The second engagement member 12 rotates in the same direction as the first engagement member 11, around the same axis AL1 as the first engagement member 11. A plurality of second gear teeth 14 that mesh with the plurality of first gear teeth 13 are formed around the entire circumference in the rotational direction at the end of the second engagement member 12 on the first engagement member 11 side in the axial direction DR1. The plurality of second gear teeth 14 are spaced apart and form a row. For this reason, the plurality of second gear teeth 14 are also referred to as a row of second gear teeth 14. A second gap 16 exists between adjacent second gear teeth 14 in the rotational direction.

[0014] The second engagement member 12 is connected to the rotation axis of the tire (i.e., the axle). The first gear teeth 13 and the second gear teeth 14 mesh with each other (i.e., fit together), so that the first engagement member 11 and the second engagement member 12 are engaged with each other (i.e., connected to each other).

[0015] The actuator 20 moves the first engagement member 11 to one side and the other side in the axial direction DR1. The movement of the first engagement member 11 in the axial direction DR1 enables switching between an engaged state in which the first engagement member 11 and the second engagement member 12 are engaged with each other as the multiple first gear teeth 13 and multiple second gear teeth 14 mesh with each other, and a released state in which the first engagement member 11 and the second engagement member 12 are separated. When switching from the released state to the engaged state, the first engagement member 11 moves in the axial direction D1 toward the second engagement member 12. An electric motor or an electromagnetic solenoid is used as the actuator 20.

[0016] The electric motor 30 is a drive source that provides the first engagement member 11 with a rotational force that rotates the first engagement member 11. In other words, the electric motor 30 rotates the first engagement member 11.

[0017] The phase difference sensor 40 is used to detect the phase difference, i.e., the relative phase, between the first engagement member 11 and the second engagement member 12. The phase difference is the difference between the phase of the first engagement member 11 and the phase of the second engagement member 12. The relative phase is the relationship between the phase of the first engagement member 11 and the phase of the second engagement member 12. The phase refers to the position of the gear teeth in the circumferential direction and has the same meaning as the rotation angle. When there is no phase difference, multiple first gear teeth 13 and multiple second gear teeth 14 mesh with each other, allowing the first engagement member 11 and the second engagement member 12 to engage with each other. When there is a phase difference, the first gear teeth 13 and the second gear teeth 14 collide with each other, preventing the first engagement member 11 and the second engagement member 12 from engaging with each other. The phase difference sensor 40 outputs a sensor signal corresponding to the phase difference, as described below.

[0018] As shown in FIG. 2, the phase difference sensor 40 has a detection range 41. The phase difference sensor 40 is installed at a position within the detection range where both the first gear teeth 13 and the second gear teeth 14 can fit. More specifically, as shown in FIG. 1, the phase difference sensor 40 is installed outside the first gear teeth 13 and the second gear teeth 14 in a radial direction DR2 centered on the axis AL1. The radial direction DR2 is the same as the direction perpendicular to the axis AL1. The outside of the radial direction DR2 is the side away from the center in the radial direction DR2. In this way, the phase difference sensor 40 is installed at a position that does not interfere with the engagement between the first engagement member 11 and the second engagement member 12. The phase difference sensor 40 outputs a sensor signal corresponding to the area of ​​the first gear teeth 13 and the second gear teeth 14 within the detection range 41. For example, a Hall element or a distance sensor may be used as the phase difference sensor 40.

[0019] The phase difference sensor 40 is connected to the input side of the arithmetic and control device 50. A sensor signal from the phase difference sensor 40 is input to the arithmetic and control device 50. The actuator 20 and the electric motor 30 are connected to the output side of the arithmetic and control device 50. The arithmetic and control device 50 is a control unit that controls the operation of the electric motor 30 and also the operation of the actuator 20.

[0020] The arithmetic and control device 50 is composed of a microcomputer including a processor and memory, and its peripheral circuits. The memory stores control programs and control data for controlling the operation of the electric motor 30 and the actuator 20. The processor executes the control programs to perform various processes.

[0021] Next, we will explain the sensor signal of the phase difference sensor 40. The time-series data of the sensor signal of the phase difference sensor 40 is a composite wave of two waveforms corresponding to the rotation speeds and phases of the first engagement member 11 and the second engagement member 12, as shown below.

[0022] 2 shows a case where the first engagement member 11 and the second engagement member 12 rotate in the same rotational direction DR3, there is no difference in rotational speed between them, and their relative phases are in an engageable state. The engageable state is a state in which the gear teeth of the first engagement member 11 and the second engagement member 12 do not collide with each other. FIG. 2 shows multiple relative positions of the detection range 41 with respect to the first engagement member 11 and the second engagement member 12 when the first engagement member 11 and the second engagement member 12 are rotating. In this case, the area of ​​the gear teeth of the first gear teeth 13 and the second gear teeth 14 present in the detection range 41 of the phase difference sensor 40 is constant at any position in the circumferential direction.

[0023] Therefore, as shown in Figure 3, the value of the sensor signal is constant over time. That is, in the time-series data of the sensor signal, the amplitude is 0. When the actuator 20 is moved in this state, the first engagement member 11 and the second engagement member 12 can be engaged smoothly without any failure.

[0024] 4 shows a case where the first engagement member 11 and the second engagement member 12 rotate in the same rotational direction DR3, there is no difference in rotational speed between them, and their relative phases are in an inengageable state. The inengageable state is a state in which the gear teeth of the first engagement member 11 and the second engagement member 12 collide with each other. In this case, the first gear teeth 13 and the second gear teeth 14 rotate together, with the first gear teeth 13 and the second gear teeth 14 facing each other in the axial direction DR1.

[0025] Therefore, as shown in FIG. 5, the time series data of the sensor signal has a waveform with a period equal to the rotation angle of one gear tooth.

[0026] FIG. 6 also illustrates a case in which the first engagement member 11 and the second engagement member 12 rotate in the same rotational direction DR3 but have a difference in rotational speed between them. In FIG. 6, the rotational speed of the second engagement member 12 is greater than that of the first engagement member. In this case, as shown in FIG. 7, the time-series data of the sensor signal has a beat waveform as shown in FIG. 7. In this beat waveform, the constant value of the engageable state in FIG. 3 and the sine wave of the disengageable state in FIG. 5 are repeated in a cycle in which the first gear tooth 13 and the second gear tooth 14 are shifted by one. As shown in FIG. 3, when there is no phase difference, the amplitude is minimum, and therefore the node portion of the beat waveform shown in FIG. 7 corresponds to the timing Nd of the engageable state. Therefore, it is possible to determine the timing of the engageable state when the amplitude of the sensor signal is below a predetermined value.

[0027] Even when the timing is such that the first engaging member 11 and the second engaging member 12 are engaged when the difference in rotation speed between them is large, a large shock occurs after engagement. For this reason, it is necessary to engage them in a region where the difference in rotation speed is within a predetermined range. Therefore, in this embodiment, the rotation speed is adjusted so that the rotation of the rotating shaft of the electric motor 30 (i.e., the electric motor shaft) approaches that of the axle rotating at a certain speed, and control is performed to engage them when the difference in rotation speed is equal to or less than a predetermined value.

[0028] The change in the rotation speed of the electric motor 30 over time when the rotation speed is adjusted is also called the rotation speed profile or the time change characteristics of the rotation speed of the electric motor 30. Here, the change in the rotation speed of the electric motor 30 over time (e.g., an increase in the rotation speed) over time when the rotation speed is adjusted occurs instantaneously, such as within one second, so the change in the rotation speed on the axle side over time can be ignored. Therefore, the change in the difference in the rotation speed between the first engagement member 11 and the second engagement member 12 over time depends on the change in the rotation speed of the electric motor 30 over time. The change in the rotation speed of the electric motor 30 over time when the rotation speed is adjusted is determined by the control characteristics of the electric motor 30. Therefore, the change in the difference in the rotation speed over time when the rotation speed is adjusted is determined for each electric motor 30 product.

[0029] Therefore, the change over time in the rotation speed of the electric motor 30 when the rotation speed adjustment is being performed is stored in advance by the arithmetic and control device 50. The future rotation speed difference can be predicted by the arithmetic and control device 50 based on the rotation speed difference between the first engagement member 11 and the second engagement member 12 when the rotation speed adjustment is started and the time change characteristics of the rotation speed of the electric motor 30. Furthermore, the arithmetic and control device 50 can predict the time when the future rotation speed difference will become a predetermined rotation speed difference.

[0030] Furthermore, the timing of the engageable state occurs at a cycle corresponding to the change over time in the rotational speed difference during rotational speed adjustment, so the arithmetic and control device 50 can calculate the future timing of the engageable state based on the time-series data of the sensor signal and the change over time in the rotational speed of the electric motor 30 during rotational speed adjustment.

[0031] Furthermore, as shown in Fig. 8, the arithmetic and control device 50 stores a plurality of past engageable state timings Np. The time intervals between the engageable state timings in the plurality of past engageable state timings change over time. By predicting this change after the current time, it is possible to predict the future engageable state timing. Therefore, the arithmetic and control device 50 can also predict the future engageable state timing Nf based on the relationship between the engageable state timing found from the plurality of past engageable state timings and elapsed time.

[0032] When the difference between the timing of the future engageable state calculated as described above and the current time becomes equal to the clutch actuation delay time, the arithmetic and control device 50 issues an engagement command to the actuator 20. This makes it possible to engage the first engaging member 11 and the second engaging member 12 without the gear teeth colliding with each other.

[0033] Furthermore, as shown in Fig. 9, when the first engagement member 11 and the second engagement member 12 are engaged, the first engagement member 11 and the second engagement member 12 rotate at the same speed, and the first gear teeth 13 and the second gear teeth 14 mesh with each other, minimizing the gap between them. Therefore, as shown in Fig. 10, the time series data of the sensor signal of the phase difference sensor 40 has a maximum constant value. From this, it is also possible to determine whether or not the engagement is occurring from the time series data of the sensor signal of the phase difference sensor 40.

[0034] However, even if the rotational speed difference between the axle and the motor shaft falls below a predetermined value, allowing the first gear teeth 13 and the second gear teeth 14 to mesh, if the relative phase is calculated to be in an unengageable state, engagement must wait until the relative phase becomes engageable. This waiting period delays the engagement of the dog clutch 10. As a result, the responsiveness of the dog clutch 10 is poor.

[0035] Therefore, as shown in FIG. 11 , in this embodiment, the arithmetic and control device 50 corrects the rotational speed of the electric motor shaft so that the timing of the engageable state arrives at the timing when the rotational speed difference between the two shafts becomes equal to or less than a predetermined value. Specifically, after starting rotational speed adjustment to bring the rotational speeds of the first engaging member 11 and the second engaging member 12 closer to each other, the arithmetic and control device 50 performs phase correction control at a time before the rotational speed difference between the two becomes equal to or less than the predetermined value. In this phase correction control, the arithmetic and control device 50 predicts a target engagement time (i.e., a target time for engagement) when the rotational speed difference becomes equal to or less than the predetermined value, and also predicts the timing of the engageable state after the target engagement time. The target engagement time and the target time for engagement correspond to the arrival times when the rotational speed difference becomes equal to or less than the predetermined value when the rotational speed adjustment is performed. The timing of the engageable state after the target engagement time corresponds to the engageable time after the arrival time.

[0036] The arithmetic and control device 50 then performs phase correction on the rotating first engagement member 11 to coincide with the predicted timing of the engageable state with the target engagement time. In this phase correction, as shown in area A1 in FIG. 11 , the arithmetic and control device 50 changes the phase of the first engagement member 11 by varying the rotational speed of the electric motor 30 in response to the time-dependent change in the rotational speed of the electric motor 30 during rotational speed adjustment without phase correction, as indicated by the dashed line. This phase correction is performed only during a portion of the rotational speed adjustment period. This phase correction changes the relative phase of the gear teeth, thereby controlling the timing of the engageable state. As shown in FIG. 11 , this phase correction causes the engageable state timing tcf to coincide with the target engagement time tt, when the rotational speeds of both shafts fall below a predetermined value. In FIG. 11 , when the rotational speed difference falls below a predetermined value ωs, an engageable rotational speed difference flag Fg is set, indicating that the rotational speed difference is engageable. An engageable time flag, indicating the timing of the engageable state, is set at the timing of a node in the time-series data of the sensor signal from the phase difference sensor 40. The timing at which the engageable rotational speed difference flag Fg is set coincides with the timing at which the engageable time flag is set.

[0037] According to this embodiment, the engagement can be achieved at the timing when the rotation speeds of both shafts become equal to or lower than a predetermined value. There is no need to wait for the engagement after the rotation speeds of both shafts become equal to or lower than the predetermined value. This makes it possible to dramatically improve responsiveness. In phase correction, the arithmetic and control device 50 is not limited to correction to decrease the rotation speed, but may also perform correction to increase the rotation speed.

[0038] Next, the arithmetic and control of this embodiment executed by the arithmetic and control device 50 will be specifically described. When receiving an engagement command, the arithmetic and control device 50 performs the process shown in FIG. 12 to engage the dog clutch 10. The steps shown in the figure correspond to functional units that realize various functions. This also applies to the other figures.

[0039] In step S1, the arithmetic and control device 50 stores the instruction time t1 when the engagement instruction is received.

[0040] Next, in step S2, the arithmetic and control device 50 detects the first rotation speed ω1 of the first engagement member 11 and the second rotation speed ω2 of the second engagement member 12. A resolver built into the electric motor 30 is used to detect the first rotation speed ω1. A wheel speed sensor is used to detect the second rotation speed ω2.

[0041] Next, in step S3, the arithmetic and control device 50 calculates the torque Tω of the electric motor 30 required to make the difference in rotation speed between the first engaging member 11 and the second engaging member 12 equal to or less than a predetermined value ωs. The predetermined value ωs is 0 or a numerical value greater than 0. The calculation of the torque Tω uses the first rotation speed ω1 and the second rotation speed ω2 detected in step S3 and the time change characteristics of the rotation speed of the electric motor 30 that are stored in advance.

[0042] Subsequently, in step S4, the arithmetic and control device 50 outputs the torque Tω to the electric motor 30. As a result, the first rotation speed ω1 of the first engagement member 11 connected to the electric motor 30 starts to change.

[0043] Next, in step S5, the arithmetic and control device 50 predicts the future rotation speed difference Δω and predicts the target engagement time tt when the future rotation speed difference Δω will be equal to or less than a predetermined value ωs. The prediction of the future rotation speed difference Δω and the target engagement time tt is performed based on the first rotation speed ω1 and second rotation speed ω2 detected in step S2 and the time change characteristics of the rotation speed of the electric motor 30.

[0044] Next, in step S6, the arithmetic and control device 50 detects and stores a plurality of timings tc of engageable states at times before the target time tt of engagement, based on the time series data of the sensor signal of the phase difference sensor 40.

[0045] Next, in step S7, the arithmetic and control device 50 determines whether the current time tn has passed the start time t2 of phase control. The start time t2 of phase control is set to an arbitrary time obtained by subtracting predetermined times such as the clutch delay time and the time required for torque control from the target time tt of engagement. If the determination is YES, the arithmetic and control device 50 proceeds to step S8 and starts phase correction control. If the determination is NO, the arithmetic and control device 50 returns to step S6.

[0046] In step S8, the arithmetic and control device 50 predicts one or more engageable state timings tcf after the target engagement time tt based on the relationship between the engageable state timings tc found from the multiple engageable state timings tc stored in step S6 and the elapsed time. As described above, the engageable state timings occur at a period corresponding to the time change in the rotational speed of the electric motor 30 during rotational speed adjustment. The nodes of the beat waveform shown in FIG. 7 indicate the engageable state timings. For these reasons, in step S8, the arithmetic and control device 50 may predict the engageable state timings tcf after the target engagement time tt based on the time-series data of the sensor signal of the phase difference sensor 40 during rotational speed adjustment and the time change characteristics of the rotational speed of the electric motor 30 during rotational speed adjustment. The time change characteristics of the rotational speed of the electric motor 30 correspond to the time change characteristics of the rotational speed difference.

[0047] Subsequently, in step S9, the arithmetic and control device 50 calculates the time difference Δt between the timing tcf of the engageable state and the target time tt of engagement.

[0048] Subsequently, in step S10, the arithmetic and control device 50 calculates a correction torque Tθ1 of the electric motor 30 according to the time difference Δt calculated in step S9. The correction torque Tθ1 of the electric motor 30 according to the time difference Δt is the torque of the electric motor 30 for making the time difference Δt zero. The correction torque Tθ1 is calculated based on the relationship between the input torque and the change in the timing of the engageable state, which is known in advance.

[0049] Next, in step S11, the arithmetic and control device 50 outputs the correction torque Tθ to the electric motor 30. That is, the arithmetic and control device 50 outputs a control signal for setting the torque of the electric motor 30 to the correction torque Tθ1. As a result, as shown in area A1 in FIG. 11, the rotation speed of the electric motor shaft is reduced relative to the change in the rotation speed of the electric motor 30 over time when the rotation speed is adjusted without phase correction. As a result, as shown in FIG. 11, the timing tcf of the engageable state after the phase correction coincides with the target time tt for engagement. Note that, as shown in FIG. 11, the phase correction is performed within a range in which the target time tt for engagement does not change.

[0050] Next, in step S12, the arithmetic and control device 50 determines whether the current time tn has reached the clutch actuation start time t3, which is earlier than the target engagement time tt. The clutch actuation start time t3 is the time obtained by subtracting the time for clutch actuation delay, safety margin, etc. from the target time tt. If the determination is YES, the arithmetic and control device 50 proceeds to step S13. If the determination is NO, the arithmetic and control device 50 returns to step S12 after a predetermined time has elapsed.

[0051] In step S13, the arithmetic and control device 50 actuates the dog clutch 10. That is, the arithmetic and control device 50 actuates the actuator 20 to engage the dog clutch 10. This ends the processing shown in FIG.

[0052] In the process shown in Fig. 12, step S2 corresponds to a rotation speed detection unit that detects a first rotation speed of the first engagement member and detects a second rotation speed of the second engagement member. Step S5 corresponds to an arrival time prediction unit that predicts the arrival time when the rotation speed difference when rotation speed adjustment is performed will reach a predetermined value or less. Step S8 corresponds to an engagement time prediction unit that predicts the engagement possible time when the first engagement member and the second engagement member will be able to engage after the arrival time predicted by the arrival time prediction unit. Steps S10 and S11 correspond to a phase correction unit that performs phase correction on at least one of the first engagement member and the second engagement member.

[0053] In this embodiment, the adjustment of the rotation speed of the first engaging member 11 is started while the first engaging member 11 is rotating. However, the adjustment of the rotation speed of the first engaging member 11 may also be started while the first engaging member 11 is stopped.

[0054] (Second embodiment) In this embodiment, as shown in area A2 in FIG. 13, the arithmetic and control device 50 performs phase correction throughout the entire rotation speed adjustment period. This phase correction is the same as in the first embodiment. Other configurations of this embodiment are the same as in the first embodiment. This embodiment also achieves the same effects as the first embodiment. This embodiment is effective in cases where the inertia of the rotating part is large, such as in a large motor, making it difficult to perform phase correction in a short period of time.

[0055] (Third embodiment) In the first embodiment, the phase is corrected based on the difference between the predicted timing tcf of the engageable state and the target engagement time (i.e., the target time tt for engagement). In contrast, in this embodiment, as shown in Fig. 14, the phase difference at the target engagement time is predicted, and the phase is corrected based on this predicted phase difference.

[0056] 14 shows the change over time in the phase difference between the first engaging member 11 and the second engaging member 12 when the rotation speeds are adjusted to keep the difference in rotation speed between the first engaging member 11 and the second engaging member 12 at or below a predetermined value. The timing when the engagement state is possible occurs when the phase difference is 0 degrees and 360 degrees. The phase difference changes over time between 0 degrees and 360 degrees.

[0057] The phase difference at the target engagement time can be calculated based on the timing of multiple engageable states before the target engagement time and the respective rotational speeds of the first engagement member 11 and the second engagement member 12. Furthermore, in the beat waveform shown in FIG. 7, the phase difference is 0 degrees when the amplitude is minimum, and 180 degrees when the amplitude is maximum. Therefore, the phase difference at the target engagement time can also be calculated based on the time-series data of the sensor signal and the change over time in the rotational speed difference when the rotational speed is adjusted. Furthermore, the phase difference at the target engagement time can also be calculated by linearly interpolating the timing of the engageable state immediately before the target engagement time and the timing of the engageable state immediately after the target engagement time.

[0058] Therefore, the arithmetic and control device 50 predicts the target engagement time and predicts the phase difference Xa between the first engagement member 11 and the second engagement member 12 at the target engagement time, as shown by the solid line in FIG. 14. The arithmetic and control device 50 corrects the rotation speed of the electric motor 30, i.e., the torque of the electric motor 30, so that the phase difference at the predicted target engagement time becomes 0 degrees. The corrected torque is determined based on a map showing the relationship between the input torque amount, torque input time, and the amount of phase difference change. This phase correction changes the phase difference as shown by the phase difference after phase correction, indicated by the dashed line Xb in FIG. 14, and the phase difference at the target engagement time changes to 0 degrees, as indicated by the arrow Xc. The torque input tx in FIG. 14 represents the phase correction. According to this embodiment, the timing of the engageable state coincides with the target engagement time. Therefore, the same effects as those of the first embodiment can be obtained.

[0059] Next, a specific description will be given of the arithmetic and control of this embodiment executed by the arithmetic and control device 50. When receiving an engagement command, the arithmetic and control device 50 performs the process shown in Fig. 15 to engage the dog clutch 10.

[0060] In the flowchart of Fig. 15, steps S9, S10, and S11 are changed to steps S9-1, S10-1, and S11-1, respectively, in the flowchart of Fig. 12. The other steps in Fig. 15 are the same as those in Fig. 12.

[0061] In step S9-1, the arithmetic and control device 50 calculates the phase difference θtt at the target time tt for engagement. The phase difference θtt is calculated by the method described above.

[0062] Next, in step S10-1, the arithmetic and control device 50 calculates a correction torque Tθ2 corresponding to the phase difference θtt at the target time tt for engagement. This correction torque Tθ2 is determined based on the above map so as to change the phase difference θtt to 0 degrees.

[0063] Next, in step S11-1, the arithmetic and control device 50 outputs the correction torque Tθ2 to the electric motor 30. This changes the rotation speed of the electric motor 30. As a result, as shown in FIG. 14, the phase difference θtt after the phase correction at the target time tt for engagement becomes 0 degrees.

[0064] 15, step S9-1 corresponds to a phase difference prediction unit that predicts the phase difference between the first engagement member and the second engagement member at the arrival time predicted by the arrival time prediction unit. Steps S10-1 and S11-1 correspond to a phase correction unit that performs phase correction on at least one of the first engagement member and the second engagement member.

[0065] (Fourth embodiment) FIG. 16 shows a case in which the second engagement member 12 on the axle side is rotating and the first engagement member 11 on the motor shaft side is stopped, and then the first engagement member 11 starts rotating at time ty, and the rotation speed of the first engagement member 11 is adjusted to the same rotation speed as the second engagement member 12. In FIG. 16, the engageable state timing tcf occurs after the target engagement time (i.e., target engagement time tt) at which the rotation speed difference becomes smaller than the predetermined value, resulting in an engageable rotation speed difference. In this case, even if the rotation speed difference becomes the engageable rotation speed difference, engagement must wait until the relative phase becomes engageable. This results in poor responsiveness of the dog clutch 10.

[0066] Changing the rotation start timing of the first engagement member 11 can change the timing tcf of the engageable state. Therefore, in this embodiment, as shown in FIG. 17, the calculation and control device 50 adjusts the rotation start timing ty of the first engagement member 11 so that the timing of the engageable state coincides with the target time tt for engagement, which is the engageable rotation speed difference. In FIG. 17, the rotation start timing of the first engagement member 11 is changed from the time indicated by the dashed line to the time indicated by the solid line. In FIG. 17, the time when the engageable time flag is set is the timing of the engageable state. In this way, the same effect as in the first embodiment can be obtained by matching the timing of the engageable state with the target time tt for engagement.

[0067] In this embodiment, the arithmetic and control device 50 predicts the timing tcf of the engageable state after the target engagement time tt based on the change over time in the phase of the rotating second engagement member 12, the phase of the stationary first engagement member 11, and the time change characteristics of the rotation speed of the electric motor 30. In this manner, the timing tcf of the engageable state can be predicted. At this time, the arithmetic and control device 50 detects the phase of the first engagement member 11 and the phase of the second engagement member 12 as follows.

[0068] 18 and 19, when the second engagement member 12 is rotating and the first engagement member 11 is stopped, the offset amount changes in the waveform representing the time-series data of the sensor signal depending on whether the first gear tooth 13 of the first engagement member 11 on the stopped side is present within the detection range 41 of the phase difference sensor 40. As shown in FIG. 20, when the first gear tooth 13 of the first engagement member 11 on the stopped side is present within the detection range 41 of the phase difference sensor 40, the sensor signal waveform is as shown in FIG. 18. As shown in FIG. 21, when the first gear tooth 13 of the first engagement member 11 on the stopped side is not present within the detection range 41 of the phase difference sensor 40, the sensor signal waveform is as shown in FIG. 19.

[0069] 18 and 19, the DC component of the time-series data of the sensor signal when the first gear tooth 13 of the first engagement member 11 on the stop side is present within the detection range 41 is larger than when it is not present within the detection range 41. Thus, there is a predetermined relationship between the DC component of the time-series data of the sensor signal and the phase of the first gear tooth 13 of the first engagement member 11 on the stop side. For this reason, the arithmetic and control device 50 can determine the DC component using a low-pass filter or time averaging, and detect the phase of the first gear tooth 13 of the first engagement member 11 on the stop side from the determined DC component.

[0070] 18 and 19 correspond to the phase change of the second gear teeth 14 of the rotating second engagement member 12. Therefore, the arithmetic and control device 50 can detect the phase of the rotating second engagement member 12 from the AC component.

[0071] Next, a specific description will be given of the arithmetic and control of this embodiment executed by the arithmetic and control device 50. When receiving an engagement command, the arithmetic and control device 50 performs the process shown in Fig. 22 to engage the dog clutch 10.

[0072] In step S21, the arithmetic and control device 50 stores the instruction time t1 when the engagement instruction is received, similarly to step S1 in FIG.

[0073] 12, the arithmetic and control device 50 detects the first rotation speed ω1 of the first engagement member 11 and the second rotation speed ω2 of the second engagement member 12. Since the second engagement member 12 is rotating and the first engagement member 11 is stationary, the first rotation speed ω1 is 0.

[0074] Next, in step S23, similar to step S3 in FIG. 12, the arithmetic and control device 50 calculates the torque Tω of the electric motor 30 required to make the difference in rotation speed between the first engagement member 11 and the second engagement member 12 equal to or less than a predetermined value ωs.

[0075] Next, in step S24, the arithmetic and control device 50 predicts the target time tt for engagement when the rotational speed difference Δω will be equal to or less than a predetermined value ωs. The prediction of the target time tt is performed based on the first rotational speed ω1 and the second rotational speed ω2 detected in step S22 and the time change characteristics of the rotational speed of the electric motor 30. Here, the rotation start time of the first engagement member 11 is set as a tentative time.

[0076] Subsequently, in step S25, the arithmetic and control device 50 detects the stop phase θ1 of the stopped first engagement member 11. At this time, the stop phase θ1 is detected based on the DC component of the time-series data of the sensor signal of the phase difference sensor 40, as described above.

[0077] Subsequently, in step S26, the arithmetic and control device 50 detects the rotational phase θ2 of the rotating second engagement member 12. At this time, the rotational phase θ2 is detected based on the AC component of the time-series data of the sensor signal of the phase difference sensor 40, as described above.

[0078] Next, in step S27, the calculation and control device 50 calculates the timing tcf of the engagement possible state after the target engagement time tt based on the time change characteristics of the rotation speed of the electric motor 30 and the stop phase θ1 and rotation phase θ2 detected in steps S25 and S26.

[0079] Subsequently, in step S28, the arithmetic and control device 50 calculates the time difference Δt between the timing tcf of the engageable state and the target time tt of engagement.

[0080] Next, in step S29, the arithmetic and control device 50 determines whether the time difference Δt is equal to or less than a threshold value t4. If the timing tcf of the engageable state is to coincide with the target time tt, the threshold value t4 is set to 0. If the determination in step S29 is NO, the process returns to step S24 after a predetermined time has elapsed. In step S24, the target time tt is predicted again. If the determination in step S29 is YES, the process proceeds to step S30.

[0081] In step S30, the arithmetic and control device 50 outputs torque Tω to the electric motor 30 at the rotation start time of the first engagement member 11, which corresponds to the target time tt. This starts rotation of the first engagement member 11. As a result, as shown in FIG. 17, the timing tcf of the engageable state coincides with the target time tt for engagement.

[0082] Next, the arithmetic and control device 50 performs steps S31 and S32. Steps S31 and S32 are the same as steps S12 and S13 in Fig. 12. As a result, the dog clutch 10 is engaged, and the process shown in Fig. 22 ends.

[0083] In the process shown in FIG. 22 , step S22 corresponds to a rotation speed detection unit that detects the first rotation speed of the first engagement member and the second rotation speed of the second engagement member. Step S24 corresponds to an arrival time prediction unit that predicts the arrival time when the rotation speed difference when the rotation speed adjustment is performed will reach a predetermined value or less. Step S26 corresponds to a rotation side detection unit that detects the time change in the phase of one of the rotating engagement members, the first engagement member or the second engagement member, based on the AC component of the time-series data of the sensor signal of the phase difference sensor. Step S25 corresponds to a stop side detection unit that detects the phase of the other of the first engagement member or the second engagement member that is stationary, based on the DC component of the time-series data of the sensor signal of the phase difference sensor. Step S27 corresponds to an engagement time prediction unit that predicts the engagement possible time when the first engagement member and the second engagement member can engage after the arrival time predicted by the arrival time prediction unit. Steps S29 and S30 correspond to a phase correction unit that performs phase correction on at least one of the first engagement member and the second engagement member at a time before the arrival time.

[0084] In this embodiment, when the second engagement member 12 is rotating and the first engagement member 11 is stopped, the arithmetic and control device 50 adjusts the rotation start timing of the first engagement member 11, which is the timing at which torque is input to the first engagement member 11. This is not limited to this case, and when both are rotating, the start timing of adjustment of the rotation speed of the first engagement member 11, which is the timing at which torque is input to the first engagement member 11, may be adjusted. In this case, too, the same effect as in this embodiment can be obtained.

[0085] (Other embodiments) (1) In each of the above-described embodiments, the arithmetic and control device 50 performs phase correction on the first engagement member 11 so that the timing of the engageable state coincides with the target time. However, this is not limiting, and the arithmetic and control device 50 may perform phase correction on the first engagement member 11 so that the timing of the engageable state approaches the target time compared to when phase correction is not performed. This also improves responsiveness compared to when phase correction is not performed.

[0086] Specifically, in the first embodiment, in steps S10 and S11, the arithmetic and control device 50 performs phase correction on the first engaging member 11 so that the time difference Δt calculated in step S9 becomes 0. However, the arithmetic and control device 50 may perform phase correction on the first engaging member 11 so that the time difference Δt calculated in step S9 becomes closer to 0 compared to when phase correction is not performed.

[0087] Furthermore, in the third embodiment, in steps S10-1 and S11-1, the arithmetic and control device 50 performs phase correction on the first engaging member 11 based on the phase difference θtt at the target engagement time tt predicted in step S9-1 so that the phase difference at the target engagement time tt becomes the phase difference in the engageable state. Without being limited to this, the arithmetic and control device 50 may perform phase correction on the first engaging member 11 based on the phase difference θtt at the target engagement time tt predicted in step S9-1 so that the phase difference at the target engagement time tt approaches the phase difference in the engageable state.

[0088] Furthermore, in the fourth embodiment, in steps S10 and S11, the arithmetic and control device 50 adjusts the rotation start timing of the first engagement member 11 as phase correction so that the time difference Δt calculated in step S28 becomes 0. However, the present invention is not limited to this, and the arithmetic and control device 50 may adjust the rotation start timing of the first engagement member 11 so that the time difference Δt calculated in step S28 becomes closer to 0 compared to when phase correction is not performed.

[0089] (2) The power transmission system 1 of each of the above-described embodiments is mounted on a vehicle and is used to transmit and interrupt power from the electric motor 30 to drive wheels, but may be used for other purposes. In addition, in the power transmission system 1 of each of the above-described embodiments, the first engagement member 11 moves in the axial direction DR1. However, depending on the application, the second engagement member 12 may also move in the axial direction DR1. Both the first engagement member 11 and the second engagement member 12 may also move in the axial direction DR1. In other words, it is sufficient that at least one of the first engagement member 11 and the second engagement member 12 moves in the axial direction DR1 by an actuator.

[0090] Furthermore, in each of the above-described embodiments, the phase of the first engagement member 11 is corrected by adjusting the rotation speed of the first engagement member 11. However, depending on the application, the phase of the second engagement member 12 may be corrected by adjusting the rotation speed of the second engagement member 12. The phases of both the first engagement member 11 and the second engagement member 12 may be corrected by adjusting the rotation speed of both the first engagement member 11 and the second engagement member.

[0091] (3) In each of the above-described embodiments, a resolver built into the electric motor 30 is used to detect the first rotation speed ω1 of the first engagement member 11. A wheel speed sensor is used to detect the second rotation speed ω2 of the second engagement member 12. However, the phase difference sensor 40 may be used to detect each of the first rotation speed ω1 and the second rotation speed ω2. The time-series data of the sensor signal of the phase difference sensor 40 includes information on the first rotation speed ω1, the second rotation speed ω2, and the difference between them. Therefore, each of the first rotation speed ω1 and the second rotation speed ω2 can be detected based on the time-series data of the sensor signal of the phase difference sensor 40.

[0092] (4) The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate, including various variations and variations within the scope of equivalents. Furthermore, the above-described embodiments are not unrelated to each other, and can be combined as appropriate, except in cases where the combination is clearly impossible. Furthermore, in the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are specifically stated as essential or where they are clearly considered essential in principle.

[0093] (5) The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible recording medium.

Claims

1. 1. A dog clutch control system, comprising: a dog clutch (10) having: a first engagement member (11) that rotates about an axis (AL1) and has a plurality of first gear teeth (13) formed over the entire circumference in the rotational direction when rotating about the axis; and a second engagement member (12) that rotates about the axis in the same direction as the first engagement member and has a plurality of second gear teeth (14) that mesh with the plurality of first gear teeth formed over the entire circumference in the rotational direction; an actuator (20) that switches between an engaged state in which the first engagement member and the second engagement member are engaged with each other by moving at least one of the first engagement member and the second engagement member in an axial direction parallel to the axis, and a released state in which the first engagement member and the second engagement member are separated from each other; a rotation speed detection unit (S2, S22) that detects a first rotation speed of the first engagement member and a second rotation speed of the second engagement member; an arrival time prediction unit (S5, S24) that predicts a time when the rotation speed difference will reach or be equal to or less than a predetermined value when the rotation speed adjustment is performed, based on the first rotation speed and the second rotation speed detected by the rotation speed detection unit and a time change characteristic of the rotation speed difference when the rotation speed adjustment is performed to make the rotation speed difference between the first engaging member and the second engaging member equal to or less than a predetermined value; a phase correction unit (S10, S11, S10-1, S11-1, S29, S30) that performs phase correction on at least one of the first engagement member and the second engagement member at a time before the arrival time, The phase correction unit performs the phase correction to bring the engagement time at which the first engagement member and the second engagement member can engage after the arrival time closer to the arrival time, compared to when the phase correction is not performed.

2. an engagement time prediction unit (S8) that predicts the engageable time after the arrival time predicted by the arrival time prediction unit; 2. The dog clutch control system according to claim 1, wherein the phase correction unit (S10, S11) performs the phase correction when the rotational speed adjustment is being performed, and performs the phase correction so that the engageable time after the phase correction is performed is closer to the arrival time than the engageable time predicted by the engagement time prediction unit.

3. a phase difference sensor (40) that outputs a sensor signal according to a phase difference between the first engagement member and the second engagement member; 3. The dog clutch control system according to claim 2, wherein the engagement time prediction unit predicts the engageable time after the arrival time based on a time change characteristic of the rotation speed difference when the rotation speed adjustment is performed and time series data of a sensor signal of the phase difference sensor when the rotation speed adjustment is performed.

4. 3. The dog clutch control system according to claim 2, wherein the engagement time prediction unit predicts the engageable time after the arrival time based on a relationship between the engageable time and elapsed time found from timings of a plurality of engageable states before the arrival time when the rotational speed adjustment is being performed.

5. a phase difference prediction unit (S9-1) that predicts a phase difference between the first engagement member and the second engagement member at the arrival time predicted by the arrival time prediction unit, 2. The dog clutch control system according to claim 1, wherein the phase correction unit (S10-1, S11-1) performs the phase correction when the rotation speed adjustment is being performed, and performs the phase correction based on the phase difference predicted by the phase difference prediction unit so that the phase difference at the arrival time approaches a phase difference in a state in which the first engagement member and the second engagement member can be engaged.

6. an engagement time prediction unit (S27) that predicts the engageable time after the arrival time predicted by the arrival time prediction unit, 2. The dog clutch control system according to claim 1, wherein the phase correction unit (S29, S30) adjusts the start timing of the rotation speed adjustment as the phase correction so that the engageable time after the phase correction is closer to the arrival time than the engageable time predicted by the engagement time prediction unit.

7. a phase difference sensor (40) that outputs a sensor signal according to a phase difference between the first engaging member and the second engaging member; a rotation-side detection unit (S26) that detects a change over time in the phase of one of the first engagement member and the second engagement member that is rotating based on an AC component of time-series data of the sensor signal of the phase difference sensor; a stop-side detection unit (S25) that detects the phase of the other of the first engagement member and the second engagement member that is stopped based on a DC component of time-series data of the sensor signal of the phase difference sensor, 7. The dog clutch control system of claim 6, wherein the engagement timing prediction unit predicts the engagement possible time after the arrival time based on the time change in the phase of one of the engagement members detected by the rotation side detection unit, the phase of the other engagement member detected by the stop side detection unit, and the time change characteristics of the rotation speed difference when the rotation speed adjustment is performed.

Images