Automatic transmission

Abstract

To realize an automatic transmission capable of preventing transmission of driving force to an output member even though it is controlled to have a neutral state while minimizing shift shock.SOLUTION: In an automatic transmission including a transmission device 20 and a control device 60, the transmission device 20 includes an auxiliary hydraulic pressure supply device 24 for supplying hydraulic pressure to an object control valve when a hydraulic circuit has a state in which the hydraulic pressure is not supplied to the object control valve from a hydraulic pressure generation device 22, and the control device 60 executes fail-safe control to forbid the supply of hydraulic pressure by the auxiliary hydraulic pressure supply device 24, in the event of a specific failure which is the failure of the control valve such that driving force is transmitted to an output member due to transmission of driving force by an object engagement element, even though the plurality of control valves are controlled to keep the transmission device 20 in a neutral state.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an automatic transmission having friction engagement elements.

Background Art

[0002] There is known an automatic transmission having friction engagement elements that are engaged when forming a gear stage and disengaged in a neutral state. Hereinafter, the reference numerals shown in parentheses in the description of the background art are those of Patent Document 1. Patent Document 1 discloses an automatic transmission having a friction engagement element (C1) that is engaged at the first gear and disengaged in the neutral state.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The automatic transmission of Patent Document 1 includes two oil passages in which the speed at which the hydraulic oil is discharged to the friction engagement element (C1) is different. When changing from the first gear to the neutral state, by using the oil passage in which the hydraulic oil is discharged at a slow speed, a rapid decrease in the engagement pressure of the friction engagement element (C1) is prevented, and a shift shock is prevented. However, in the automatic transmission of Patent Document 1, since the decrease in the engagement pressure of the friction engagement element (C1) is delayed, for example, when an abnormality occurs such that another friction engagement element to be released does not become released, there is a possibility that a driving force is transmitted to the output member despite being controlled to be in the neutral state.

[0005] Therefore, it is desired to realize an automatic transmission that can suppress a shift shock to a small level and avoid the transmission of a driving force to the output member despite being controlled to be in the neutral state. [Means for solving the problem]

[0006] The characteristic configuration of the automatic transmission in view of the above is an automatic transmission comprising: a transmission device that transmits the rotation of an input member driven by a power source to an output member at a gear ratio of one of a plurality of gear stages, and a control device that controls the transmission device, wherein the transmission device comprises a plurality of friction engagement elements and a plurality of control valves that control the engagement state of the plurality of friction engagement elements, wherein one of the plurality of gear stages is formed according to the engagement state of the plurality of friction engagement elements, or a neutral state is set in which no driving force is transmitted between the input member and the output member, and the target gear stage among the plurality of gear stages is designated as the target gear stage, and the friction engagement element that is engaged when the target gear stage is formed and released in the neutral state is designated as the target engagement element, and a supply is provided to the target engagement element The transmission comprises a hydraulic pressure generating device that generates hydraulic pressure for engaging a plurality of friction engagement elements, a hydraulic pressure circuit capable of switching the hydraulic pressure supply path from the hydraulic pressure generating device to each of the plurality of control valves, and an auxiliary hydraulic pressure supply device that supplies hydraulic pressure to the target control valve when the hydraulic pressure circuit is in a state where hydraulic pressure from the hydraulic pressure generating device is not supplied to the target control valve. The control device performs fail-safe control by prohibiting the supply of hydraulic pressure by the auxiliary hydraulic pressure supply device if a specific failure occurs in the control valve, such that the target engagement element transmits driving force and thereby transmits driving force to the output member, even though the plurality of control valves are controlled to put the transmission in the neutral state.

[0007] With this feature configuration, if there is no failure in the control valve, when the transmission is set to neutral, hydraulic pressure is supplied from the auxiliary hydraulic supply device to the target control valve, thereby minimizing the shift shock caused by the change in state between the geared state and the neutral state. Furthermore, by prohibiting the supply of hydraulic pressure from the auxiliary hydraulic supply device to the target control valve when a specific failure occurs, the target engagement element cannot be engaged when the transmission is set to neutral, thus avoiding the transmission of driving force to the output member even though the system is controlled to be in neutral.

[0008] Further features and advantages of the technology relating to this disclosure will become clearer from the following description of exemplary and non-limiting embodiments, with reference to the drawings. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram of an automatic transmission according to an embodiment of the present invention. [Figure 2] Control block diagram of the automatic transmission shown in Figure 1. [Figure 3] Figure 1 shows the engagement table for the automatic transmission. [Figure 4] A cross-sectional view showing an enlarged view of the second brake area in Figure 1. [Figure 5] A schematic diagram illustrating the hydraulic circuit of the automatic transmission shown in Figure 1. [Figure 6] A schematic diagram showing the neutral state in the hydraulic circuit of Figure 5, where a neutral stage is formed. [Figure 7] A schematic diagram showing the drive force transmission state in the hydraulic circuit of Figure 5, where the first stage is formed. [Figure 8] A schematic diagram showing the state in which auxiliary hydraulic pressure is supplied to the first clutch in Figure 5. [Figure 9] A schematic diagram showing the power transmission state in which a reverse travel stage is formed in the hydraulic circuit of Figure 5. [Figure 10] Figure 5 shows the state in which auxiliary hydraulic pressure is supplied to the third clutch. [Figure 11]Figure 5 shows a time chart illustrating an example of switching from the first stage to the neutral stage when the sixth linear solenoid valve fails. [Figure 12] Figure 5 shows a time chart illustrating an example of switching from reverse to neutral when the sixth linear solenoid valve fails. [Figure 13] A flowchart showing the fail-safe control process by the control device shown in Figure 1. [Modes for carrying out the invention]

[0010] In the following description, the automatic transmission 10 according to the first embodiment will be explained with reference to the drawings. Figure 1 is a schematic diagram of the automatic transmission 10. Figure 2 is a control block diagram of the automatic transmission 10. In this embodiment, the automatic transmission 10 is mounted on a vehicle equipped with a vehicle power supply 11, a driving force source 12 such as a rotating electric machine, and a differential gear and wheels (not shown), and transmits the driving force input from the driving force source 12 to the differential gear device. The differential gear device distributes the input driving force to a pair of wheels. As the vehicle power supply 11, for example, a power storage device such as a battery installed inside the vehicle or a power receiving device that receives power from outside the vehicle can be used. In this application, "rotating electric machine" is used as a concept that includes motors, generators, and motor-generators that perform both motor and generator functions as needed.

[0011] The automatic transmission 10 includes a transmission device 20 that transmits the rotation of an input member 20n, driven by a power source 12, to an output member 20t at a gear ratio ν of one of several gear stages. In this embodiment, the automatic transmission 10 further includes a torque converter 30. The torque converter 30 includes a pump-side impeller 32 driven and connected to the output member 12t of the power source 12, a stator-side impeller 34 having a one-way clutch 37 between it and a case which is a non-rotating member 14, and a turbine-side impeller 36 driven and connected to the input member 20n of the transmission device 20. In the illustrated example, the torque converter 30 is also provided with a lock-up clutch, a direct-drive clutch CD1, in the power transmission path between the pump-side impeller 32 and the turbine-side impeller 36. In the illustrated example, the rotational speed of the output member 12t of the power source 12 is detected by a power source rotational speed sensor 42. The rotational speed of the input member 20n of the transmission 20 is detected by the input shaft rotational speed sensor 44. The rotational speed of the output member 20t of the transmission 20 is detected by the output shaft rotational speed sensor 46.

[0012] In this application, "drive connection" refers to a state in which two rotating elements are connected in a manner that enables the transmission of driving force, and is used as a concept that includes a state in which the two rotating elements are connected so as to rotate as a whole, or a state in which the two rotating elements are connected in a manner that enables the transmission of driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as shafts, gear mechanisms, belts, chains, etc. Furthermore, such transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices.

[0013] FIG. 3 is a diagram showing an engagement table of the automatic transmission 10. The transmission device 20 includes a plurality of friction engagement elements CL and a plurality of control valves VL that control the engagement states of the plurality of friction engagement elements CL. Depending on the engagement states of the plurality of friction engagement elements CL, any one of a plurality of shift stages is formed, or a neutral state is established in which the transmission of driving force between the input member 20n and the output member 20t is not performed. In the present embodiment, the plurality of friction engagement elements CL include a clutch C that engages rotating members with each other and a brake B that engages a non-rotating member with a rotating member. In the example shown in FIG. 1, the transmission device 20 is configured using a first planetary gear mechanism PG1 and a second planetary gear mechanism PG2.

[0014] As shown in FIGS. 1 to 3, in the present embodiment, the transmission device 20 includes a direct clutch CD1, a first clutch C1, a second clutch C2, a third clutch C3, a fourth clutch C4, a first brake B1, and a second brake B2 as a plurality of friction engagement elements CL. FIG. 4 is an enlarged cross-sectional view showing the second brake B2. In the present embodiment, the second brake B2 includes a first piston B2a and a second piston B2b, and is a double piston type friction engagement element CL that is engaged by the engagement pressure of at least one of the first piston B2a and the second piston B2b.

[0015] In the illustrated example, the second brake B2 includes a piston case 51, a first piston B2a that is an inner piston, a second piston B2b that is an outer piston, and a plurality of friction plates 52. The first piston B2a and the second piston B2b are slidably disposed within the piston case 51. O-rings 57 are fitted on the first piston B2a and the second piston B2b to seal against the inner peripheral surface of the piston case 51. A first oil chamber 54 is formed between the first piston B2a and the piston case 51. A second oil chamber 56 is formed between the second piston B2b and the piston case 51.

[0016] The tip of the first piston B2a is disposed between the second piston B2b and the friction plate 52 and is in contact with the friction plate 52. The first piston B2a is biased by a return spring 58 in a direction away from the friction plate 52. When hydraulic pressure is supplied to the first oil chamber 54, the tip of the first piston B2a presses the friction plate 52, generating an engagement pressure that engages the second brake B2. Also, when hydraulic pressure is supplied to the second oil chamber 56, the second piston B2b presses the friction plate 52 through the first piston B2a, generating an engagement pressure that engages the second brake B2.

[0017] Here, regarding the engagement state of the friction engagement element CL, a state where rotation and torque are not transmitted between the engagement members of the friction engagement element CL is defined as the "released state", and a state where rotation and torque are transmitted between the engagement members of the friction engagement element CL is defined as the "engaged state". Also, among the "engaged states", a state where the friction engagement element CL is engaged so as to transmit torque while having a differential rotation between the engagement members is defined as the "slip engagement state", and a state where the engagement members on both sides of the friction engagement element CL are engaged so as to rotate integrally is defined as the "direct connection engagement state". Note that the "released state" includes a state where, despite controlling the friction engagement element CL to be in a non-engaged state, rotation and torque are unintentionally transmitted due to, for example, the rotation of the engagement members of the friction engagement element CL.

[0018] In the present embodiment, as shown in FIG. 3, when a plurality of friction engagement elements CL marked with "○" are in the engaged state and the remaining friction engagement elements CL are in the released state, a driving force transmission state, that is, a state in which any one of a plurality of gear stages is formed, is achieved. When all of the friction engagement elements CL are in the released state, a neutral stage "N" that sets the transmission 20 to the neutral state is formed. In the present embodiment, since any one of the gear stages is formed by bringing two friction engagement elements CL into the engaged state, the neutral stage "N" is also formed even when only any one of the plurality of friction engagement elements CL is in the engaged state.

[0019] In this embodiment, the multiple gears include eight forward gears "D" with different gear ratios ν: the first gear "1st", second gear "2nd", third gear "3rd", fourth gear "4th", fifth gear "5th", sixth gear "6th", seventh gear "7th", and eighth gear "8th", and a reverse gear "R". In the forward gears "D", the gear ratio ν decreases in stages from the first gear "1st" to the eighth gear "8th", that is, from the low-speed gears to the high-speed gears. Here, the gear ratio ν is the ratio of the rotational speed of the input member 20n to the rotational speed of the output member 20t. Although not shown in Figure 3, the direct-drive clutch CD1 is preferably in a disengaged state in the neutral gear "N" and reverse gear "R", and in the forward gear "D", it is switched between engaged and disengaged states depending on conditions such as vehicle speed, throttle opening, and engine speed.

[0020] Figure 5 is a simplified diagram of the hydraulic circuit 25 of the transmission 20. The transmission 20 includes a hydraulic generator 22 that generates hydraulic pressure for engaging multiple friction engagement elements CL, and a hydraulic circuit 25 that can switch the hydraulic pressure supply path from the hydraulic generator 22 to each of the multiple control valves VL. In this embodiment, the hydraulic circuit 25 consists of multiple control valves VL and oil passages. In this embodiment, the transmission 20 has multiple control valves VL that individually control the hydraulic pressure to the multiple friction engagement elements CL in order to control the engagement state of the multiple friction engagement elements CL. In the example shown in Figure 5, the first linear solenoid valves SL1 to the sixth linear solenoid valve SL6, the first switching valve Vw1, the second switching valve Vw2, the first auxiliary hydraulic pressure supply valve Vs1, the third auxiliary hydraulic pressure supply valve Vs3, the switching control valve Vn1, the check valve Vc1, and the manual valve MV function as the multiple control valves VL. These multiple control valves VL are supplied with hydraulic pressure discharged from the oil pump OP of the hydraulic pressure generating device 22 shown in Figure 2, which has been regulated to the appropriate line pressure by the primary regulator valve Vp1, secondary regulator valve Vp2, etc.

[0021] In this embodiment, the first linear solenoid valve SL1 to the fourth linear solenoid valve SL4 adjust the supply hydraulic pressure according to the current applied to their respective solenoid sections to generate engagement pressure for engaging the first clutch C1 to the fourth clutch C4. The fifth linear solenoid valve SL5 adjusts the supply hydraulic pressure according to the current applied to its solenoid section to generate engagement pressure for engaging the first brake B1. The sixth linear solenoid valve SL6 adjusts the supply hydraulic pressure according to the current applied to its solenoid section to operate the first piston B2a and generate engagement pressure for engaging the second brake B2.

[0022] In this embodiment, the first switching valve Vw1 is a valve that switches the direct-drive clutch CD1 between the engaged side (lock-up on side) and the released side (lock-up off side), and functions as a so-called lock-up relay valve. The second switching valve Vw2 is a valve that is provided to be able to shut off the hydraulic pressure from the hydraulic pressure generator 22 to the second piston B2b and can be switched between the shut-off side and the engaged side, and functions as a so-called B2 apply control valve. The switching control valve Vn1 is a valve that outputs a signal pressure to switch the first switching valve Vw1 and the second switching valve Vw2, respectively, and functions as a so-called ON-OFF solenoid valve. Preferably, the switching control valve Vn1 outputs a signal pressure to switch the first switching valve Vw1 in the forward travel stage D, and outputs a signal pressure to switch the second switching valve Vw2 in the reverse travel stage R.

[0023] In this embodiment, the first auxiliary hydraulic supply valve Vs1 is a linear solenoid valve and functions as a so-called lock-up solenoid valve (SLU) that supplies hydraulic pressure to the direct-drive clutch CD1 to generate engagement pressure when the first switching valve Vw1 is switched to the lock-up on side. In addition, when the first switching valve Vw1 is switched to the lock-up off side, the first auxiliary hydraulic supply valve Vs1 functions as an auxiliary hydraulic supply device 24, which supplies auxiliary hydraulic pressure to the first linear solenoid valve SL1, as described later. In the example shown in Figure 5, the first auxiliary hydraulic supply valve Vs1 also functions as an auxiliary hydraulic supply device 24 for the second linear solenoid valve SL2 to the fifth linear solenoid valve SL5. In this embodiment, the third auxiliary hydraulic supply valve Vs3 is a linear solenoid valve and functions as an auxiliary hydraulic supply device 24, which supplies auxiliary hydraulic pressure to the third linear solenoid valve SL3, as described later. In the example shown in Figure 5, the third auxiliary hydraulic supply valve Vs3 also functions as an auxiliary hydraulic supply device 24 for the fourth linear solenoid valve SL4.

[0024] In this embodiment, the check valve Vc1 is a check valve that maintains the oil flow in a constant direction and restricts backflow. The manual valve MV is a switching valve that switches the line pressure supply path according to the selected shift range.

[0025] The shift range includes, for example, non-driving ranges such as parking range (P range) and neutral range (N range), and driving ranges such as reverse driving range (R range) and forward driving range (D range). One of these shift ranges is selected by the driver operating the shift lever or by the vehicle control device performing automatic driving. The forward driving range (D range) may include a brake range (B range) in which the engine braking effect is prioritized, and a sport range (S range) in which the responsiveness of the accelerator pedal is prioritized. In this embodiment, when the neutral range (N range) is selected, a neutral position N is formed and the transmission 20 is in a neutral state. Also in this embodiment, when the parking range (P range) is selected, a neutral position N is formed and the transmission 20 is in a neutral state.

[0026] Figures 6 to 10 show a simplified representation of the hydraulic circuit 25 in the neutral or power transmission state. In Figures 6 to 10, the oil passages to which hydraulic pressure is supplied from the hydraulic pressure generator 22 are shown with thick lines. The second linear solenoid valve SL2, the fourth linear solenoid valve SL4, and the fifth linear solenoid valve SL5 are omitted. Figure 6 shows the hydraulic circuit 25 in the neutral state where the neutral stage N is formed. The transmission 20 is equipped with an auxiliary hydraulic pressure supply device 24. Here, the target gear stage among the multiple gear stages is called the target gear stage H, the friction engagement element CL that is engaged when the target gear stage H is formed and released in the neutral state is called the target engagement element HC, and the control valve VL that controls the hydraulic pressure supplied to the target engagement element HC is called the target control valve HV. The auxiliary hydraulic pressure supply device 24 supplies hydraulic pressure (auxiliary hydraulic pressure) to the target control valve HV when the hydraulic circuit 25 is in a state where hydraulic pressure from the hydraulic pressure generator 22 is not supplied to the target control valve HV. Preferably, the target gear stage H is the low-speed stage and the reverse stage R. More preferably, the target gear stage H is the first stage 1st, which is the lowest forward stage, and the reverse stage R, which is the lowest reverse stage.

[0027] Figure 7 shows a simplified representation of the hydraulic circuit 25 in the drive force transmission state where the first stage 1st is formed when the first switching valve Vw1 is in the lock-up off position. Figure 8 shows the hydraulic circuit 25 in the state where it has switched from the first stage 1st to the neutral stage N and auxiliary hydraulic pressure is supplied to the first clutch C1. In the illustrated example, the target gear shift stage H is the first stage 1st, the target engagement element HC is the first clutch C1, and the target control valve HV is the first linear solenoid valve SL1. As shown in Figure 8, the auxiliary hydraulic pressure supply device 24 (i.e., the first auxiliary hydraulic pressure supply valve Vs1) supplies auxiliary hydraulic pressure to the first linear solenoid valve SL1 when the hydraulic circuit 25 is in a state where the hydraulic pressure from the hydraulic pressure generation device 22 to the first linear solenoid valve SL1 is cut off by the manual valve MV.

[0028] Figure 9 shows a simplified representation of the hydraulic circuit 25 in a drive force transmission state where the reverse travel stage R is formed. Figure 10 shows the hydraulic circuit 25 in a state where it has switched from the reverse travel stage R to the neutral stage N and auxiliary hydraulic pressure is supplied to the third clutch C3. In the illustrated example, the target gear shift stage H is the reverse travel stage R, the target engagement element HC is the third clutch C3, and the target control valve HV is the third linear solenoid valve SL3. As shown in Figure 10, the auxiliary hydraulic pressure supply device 24 (i.e., the third auxiliary hydraulic pressure supply valve Vs3) supplies auxiliary hydraulic pressure to the third linear solenoid valve SL3 when the hydraulic circuit 25 is in a state where the hydraulic pressure from the hydraulic pressure generator 22 to the third linear solenoid valve SL3 is cut off by the manual valve MV.

[0029] The automatic transmission 10 is further equipped with a control device 60 that controls the transmission 20. The control device 60 performs fail-safe control S10, which prohibits the supply of hydraulic pressure by the auxiliary hydraulic supply device 24, if a specific failure occurs in a control valve VL, such that the target engagement element HC transmits driving force and thereby transmits driving force to the output member 20t, even though multiple control valves VL are controlled to put the transmission 20 in a neutral state.

[0030] Figure 11 is a time chart showing an example of switching from the first stage 1st to the neutral stage N in a fault condition where the first piston B2a is not in the released position. Figure 12 is a time chart showing an example of switching from the reverse travel stage R to the neutral stage N in a fault condition where the first piston B2a is not in the released position.

[0031] In Figure 11, the shift range is switched to the neutral range at time t11, starting from a state where the forward driving range (D range) is selected and the gear is in the first stage (1st). If the sixth linear solenoid valve SL6 is not malfunctioning, from the state at time t11 where hydraulic pressure is supplied to the first piston B2a and the first clutch C1 (state in Figure 7), the control device 60, at time t12, cuts off the supply of oil to the first piston B2a with the sixth linear solenoid valve SL6, and also cuts off the supply path from the hydraulic pressure generator 22 to the first linear solenoid valve SL1 with the manual valve MV. Furthermore, the control device 60 opens the first auxiliary hydraulic pressure supply valve Vs1 and starts supplying auxiliary hydraulic pressure to the first linear solenoid valve SL1 (state in Figure 8). This auxiliary hydraulic pressure is controlled by the control device 60 so that the engagement pressure of the first clutch C1 is gradually reduced from time t13 to 0 at time t14. As a result, in the output member 20t of the transmission 20 shown in Figure 1, the shift shock caused by the sudden decrease in creep torque when changing from D range to N range, and the shift shock caused by re-engagement when changing between D range, N range, and R range, are suppressed to a low degree.

[0032] As shown in Figure 11, the first auxiliary hydraulic supply valve Vs1 is closed at time t15. Preferably, time t15 is a predetermined time elapsed from time t12, and is a safety setting time (guard timer) that closes the first auxiliary hydraulic supply valve Vs1 even if the engagement pressure of the first clutch C1 is not zero at time t15. Next, when the vehicle is switched from neutral range to reverse range (R range) at time t16, the engagement of the third clutch C3 is started at time t17, and the supply of oil to the second piston B2b is started at time t18.

[0033] However, in the example shown in Figure 11, the sixth linear solenoid valve SL6 is faulty, so the supply of oil to the first piston B2a is not cut off at time t12. In this state, when the control device 60 opens the first auxiliary hydraulic supply valve Vs1 and supplies auxiliary hydraulic pressure to the first clutch C1 via the first linear solenoid valve SL1, the first clutch C1 and the second brake B2 are engaged while the first clutch C1 is generating engagement pressure from time t12 to time t14, forming the first stage 1st. Therefore, even though the control is set to a neutral state, there was a possibility that the driving force of the driving force source 12 would be transmitted to the output member 20t. However, in the above case, the control device 60 closes the first auxiliary hydraulic supply valve Vs1 and prohibits the supply of hydraulic pressure to the first linear solenoid valve SL1. Therefore, it is possible to avoid the transmission of driving force to the output member 20t even though the control is set to a neutral state.

[0034] In Figure 12, the vehicle is in a state where the reverse driving range (R range) is selected and the gear is set to the reverse driving gear R. At time t21, the shift range is switched to the neutral range. If the sixth linear solenoid valve SL6 is not malfunctioning, at time t21, hydraulic pressure is supplied to the first piston B2a, the second piston B2b, and the third clutch C3 (state as shown in Figure 9). At time t22, the control device 60 cuts off the supply of oil to the first piston B2a using the sixth linear solenoid valve SL6, and also cuts off the supply path from the hydraulic pressure generator 22 to the second piston B2b and the third linear solenoid valve SL3 using the manual valve MV. Furthermore, the control device 60 opens the third auxiliary hydraulic pressure supply valve Vs3 and starts supplying auxiliary hydraulic pressure to the third linear solenoid valve SL3 (state as shown in Figure 10). This auxiliary hydraulic pressure is controlled by the control device 60 so that the engagement pressure of the third clutch C3 is gradually reduced from time t23 to 0 at time t24. As a result, in the output member 20t of the transmission 20 shown in Figure 1, the shift shock caused by the sudden decrease in creep torque when changing from the R range to the N range, and the shift shock caused by re-engagement when changing between the R range, N range, and D range, are suppressed to a low degree.

[0035] As shown in Figure 12, the third auxiliary hydraulic supply valve Vs3 is closed at time t25. Preferably, time t25 is a predetermined time elapsed from time t22, and is a safety setting time (guard timer) that closes the third auxiliary hydraulic supply valve Vs3 even if the engagement pressure of the third clutch C3 is not zero at time t25. Next, when the vehicle is switched from neutral range to forward driving range (D range) at time t26, the engagement of the first clutch C1 is started at time t27.

[0036] However, in the example shown in Figure 12, the sixth linear solenoid valve SL6 is faulty, so the supply of oil to the first piston B2a is not cut off at time t22. In this state, when the control device 60 opens the third auxiliary hydraulic supply valve Vs3 and supplies auxiliary hydraulic pressure to the third clutch C3 via the third linear solenoid valve SL3, both the third clutch C3 and the second brake B2 are engaged while the third clutch C3 is generating engagement pressure from time t22 to time t24, forming the reverse travel stage R. Therefore, even though the control is set to a neutral state, there was a possibility that the driving force of the driving force source 12 would be transmitted to the output member 20t. However, in the above case, the control device 60 closes the third auxiliary hydraulic supply valve Vs3 and prohibits the supply of hydraulic pressure to the third linear solenoid valve SL3. Therefore, it is possible to avoid the transmission of driving force to the output member 20t even though the control is set to a neutral state.

[0037] Figure 13 is a flowchart showing an example of fail-safe control S10. In fail-safe control S10, the control device 60 performs a specific fault determination process S11 to determine whether or not a specific fault has occurred. In the example shown in Figure 2, the control device 60 is equipped with a specific fault determination unit 62, and the specific fault determination unit 62 executes the specific fault determination process S11.

[0038] In this embodiment, a specific failure is a failure in which a specific engagement element TC, which is an engagement element that forms one of the gear stages in combination with the target engagement element HC, becomes engaged. In the example shown in Figure 3, when the target engagement element HC is the third clutch C3, the specific engagement elements TC are the first clutch C1, the second clutch C2, and the second brake B2.

[0039] In this embodiment, the control device 60 determines that a specific malfunction has occurred if the control valve VL that supplies hydraulic pressure to the specific engagement element TC is malfunctioning. More specifically, the control device 60 determines that a specific malfunction has occurred if the control valve VL that supplies hydraulic pressure to the specific engagement element TC cannot be controlled. It also determines that a specific malfunction has occurred if the control current or control voltage of the control valve VL that supplies hydraulic pressure to the specific engagement element TC shows an abnormal value. For example, if the specific engagement element TC is the second brake B2, the control device 60 determines that a specific malfunction has occurred if the control current or control voltage of the sixth linear solenoid valve SL6 or the switching control valve Vn1 shows an abnormal value.

[0040] Furthermore, in this embodiment, the control device 60 determines that a specific malfunction has occurred if the specific engagement element TC does not become disengaged. More specifically, the control device 60 determines that a specific malfunction has occurred if the gear stages formed by the disengagement of the specific engagement element TC are not properly formed. For example, if the specific engagement element TC is the second brake B2, the control device 60 determines that a specific malfunction has occurred if the gear stages 2nd to 8th, formed by the disengagement of the second brake B2, are not properly formed. Whether or not these gear stages 2nd to 8th are properly formed can be determined based on the difference in rotational speed between the input member 20n and the output member 20t of the transmission 20. That is, the control device 60 determines the rotational speed (min) of the input member 20n shown in Figure 1. -1 ) and the rotational speed (min) of the output member 20t -1 A specific malfunction is determined to occur if the rotational speed difference, which is the difference between the specified engagement element TC and the specified engagement element TC, falls outside a predetermined range in the gear shift stage formed when the specific engagement element TC is released.

[0041] Returning to Figure 13, if the control device 60 determines in the specific fault determination process S11 that no specific fault has occurred, it repeats the specific fault determination process S11 at a predetermined interval. If the specific fault determination process S11 determines that a specific fault has occurred, it performs the auxiliary hydraulic supply prohibition process S12, which prohibits the supply of hydraulic pressure from the auxiliary hydraulic supply device 24 to the target control valve HV. In the example shown in Figure 2, the control device 60 is equipped with an auxiliary hydraulic supply control unit 64, and the auxiliary hydraulic supply control unit 64 executes the auxiliary hydraulic supply prohibition process S12.

[0042] If the target engagement element HC is the first clutch C1, the specific engagement elements TC in the example of Figure 3 are the second clutch C2, third clutch C3, fourth clutch C4, first brake B1, and second brake B2. If any of these malfunctions and they become engaged, the supply of hydraulic pressure by the auxiliary hydraulic pressure supply device 24 is prohibited. Similarly, if the target engagement element HC is the third clutch C3, the specific engagement elements TC in the example of Figure 3 are the first clutch C1, second clutch C2, and second brake B2. If any of these malfunctions and they become engaged, the supply of hydraulic pressure by the auxiliary hydraulic pressure supply device 24 is prohibited.

[0043] Returning to Figure 13, in this embodiment, the control device 60 performs a power supply restart determination process S13 and an auxiliary hydraulic supply restart process S14. That is, when the power supply from the vehicle power supply 11 is restarted after being interrupted, the control device 60 terminates the fail-safe control S10 and allows hydraulic supply by the auxiliary hydraulic supply device 24.

[0044] In the power supply restart determination process S13, the control device 60 determines whether the power supply from the vehicle power supply 11 to the control device 60 has been restarted after being interrupted. If the power supply restart determination process S13 determines that the power supply has not been interrupted and restarted, the control device 60 repeats the power supply restart determination process S13 at a predetermined interval. In the example shown in Figure 2, the control device 60 is equipped with a power supply restart determination unit 66, and the power supply restart determination unit 66 executes the power supply restart determination process S13.

[0045] In the power supply restart determination process S13, if it is determined that the power supply from the vehicle power supply 11 to the control device 60 has been restarted after being interrupted, the control device 60 executes the auxiliary hydraulic supply restart process S14, which releases the prohibition on auxiliary hydraulic supply, that is, permits the supply of hydraulic pressure from the auxiliary hydraulic supply device 24 to the target control valve HV, and terminates the fail-safe control S10. It is preferable that the auxiliary hydraulic supply restart process S14 is also executed in other cases, for example, when a fault diagnostic clearing process is performed on the control device 60. In this embodiment, the auxiliary hydraulic supply control unit 64 executes the auxiliary hydraulic supply restart process S14.

[0046] The above-described automatic transmission 10 comprises a transmission device 20 that transmits the rotation of an input member 20n, driven by a power source 12, to an output member 20t at a gear ratio ν of one of a plurality of gear stages, and a control device 60 that controls the transmission device 20, wherein the transmission device 20 comprises a plurality of friction engagement elements CL and a plurality of control valves VL that control the engagement state of the plurality of friction engagement elements CL, wherein one of a plurality of gear stages is formed according to the engagement state of the plurality of friction engagement elements CL, or a neutral state is set in which no driving force is transmitted between the input member 20n and the output member 20t, and the target gear stage among the plurality of gear stages is designated as the target gear stage H, and the friction engagement element CL that is engaged when the target gear stage H is formed and released in the neutral state is designated as the target engagement element HC, and the target engagement element HC is supplied With the control valve VL that controls the supplied hydraulic pressure as the target control valve HV, the transmission 20 includes a hydraulic pressure generator 22 that generates hydraulic pressure to engage multiple friction engagement elements CL, a hydraulic pressure circuit 25 that can switch the hydraulic pressure supply path from the hydraulic pressure generator 22 to each of the multiple control valves VL, and an auxiliary hydraulic pressure supply device 24 that supplies hydraulic pressure to the target control valve HV when the hydraulic pressure circuit 25 is in a state where hydraulic pressure from the hydraulic pressure generator 22 is not supplied to the target control valve HV. The control device 60 performs fail-safe control S10 to prohibit the supply of hydraulic pressure by the auxiliary hydraulic pressure supply device 24 if a specific failure occurs in a control valve VL such that the target engagement element HC transmits driving force and thus drives the output member 20t, even though the multiple control valves VL are controlled to put the transmission 20 in a neutral state.

[0047] According to this configuration, when the control valve VL is not faulty, the auxiliary hydraulic supply device 24 supplies hydraulic pressure to the target control valve HV when the transmission 20 is set to neutral, thereby minimizing the shift shock caused by the change in state between the state in which the target gear stage H is formed and the neutral state. Furthermore, by prohibiting the supply of hydraulic pressure to the target control valve HV by the auxiliary hydraulic supply device 24 when a specific fault occurs, the target engagement element HC cannot be engaged when the transmission 20 is set to neutral, making it easier to avoid the transmission of driving force to the output member 20t even though the system is being controlled to be in neutral.

[0048] In the automatic transmission 10 described above, the specific failure is a failure in which a specific engaging element TC, which is an engaging element that forms one of the gear stages in combination with the target engaging element HC, becomes engaged. Therefore, even though the system is controlled to be in a neutral state, it is possible to appropriately avoid the formation of an unintended gear stage and the transmission of driving force to the output member 20t.

[0049] In the automatic transmission 10 described above, the control device 60 determines that a specific malfunction has occurred if the control valve VL that supplies hydraulic pressure to the specific engagement element TC is malfunctioning, or if the gear shifts formed by the specific engagement element TC being in a disengaged state are not properly formed. Therefore, it is possible to appropriately determine whether or not a specific malfunction has occurred.

[0050] In the automatic transmission 10 described above, the control device 60 terminates the fail-safe control S10 and allows hydraulic pressure supply by the auxiliary hydraulic pressure supply device 24 when the power supply from the vehicle power supply 11 is interrupted and then restored. Therefore, it is possible to recover appropriately from the state in which the fail-safe control S10 is being performed.

[0051] [Other Embodiments] Next, other embodiments of the automatic transmission 10 will be described.

[0052] (1) In the above embodiment, the case in which the automatic transmission 10 is mounted on a vehicle equipped with a power source 12 such as a rotating electric machine was described as an example. Here, the power source 12 is not limited to a rotating electric machine, but may be an internal combustion engine, or a hybrid of an internal combustion engine and a rotating electric machine. That is, the vehicle may be an automobile with only an internal combustion engine as the power source 12, a hybrid automobile with an internal combustion engine and a rotating electric machine as the power source 12, or an electric automobile. Furthermore, this automatic transmission 10 may be mounted on a vehicle other than an automobile.

[0053] (2) In the above embodiment, a configuration in which the second brake B2 is a double-piston type friction engagement element CL was described as an example. However, the configuration is not limited to such a configuration, and for example, the second brake B2 may be a single-piston type. Also, in the above embodiment, a configuration in which the first clutch C1 to the fourth clutch C4 and the first brake B1 are controlled by the first linear solenoid valve SL1 to the fifth linear solenoid valve SL5 was described as an example. However, it is not essential that the friction engagement element CL and the control valve VL correspond one-to-one in this way, and for example, a configuration in which multiple friction engagement elements CL are controlled by a combination of one linear solenoid valve and a switching valve is also possible.

[0054] (3) In the above embodiment, a configuration was described as in which a first auxiliary hydraulic supply valve Vs1, which functions as an auxiliary hydraulic supply device 24, supplies hydraulic pressure to the first linear solenoid valve SL1, and a third auxiliary hydraulic supply valve Vs3 supplies hydraulic pressure to the third linear solenoid valve SL3. However, the configuration is not limited to such a configuration, and for example, one auxiliary hydraulic supply valve may be provided for each of the first linear solenoid valves SL1 to the sixth linear solenoid valve SL6. Furthermore, the auxiliary hydraulic supply device 24 does not necessarily have to use linear solenoid valves, and for example, an accumulator or an electric oil pump may be used.

[0055] (4) The configurations disclosed in the embodiments described above can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. With regard to other configurations, the embodiments disclosed herein are merely illustrative in all respects. Therefore, various modifications can be made as appropriate without departing from the spirit of this disclosure. [Industrial applicability]

[0056] The technology disclosed herein can be used in vehicles equipped with an automatic transmission. [Explanation of Symbols]

[0057] 10: Automatic transmission, 11: Vehicle power supply, 12: Drive source, 20: Transmission, 20n: Input component, 20t: Output component, 22: Hydraulic generation device, 24: Auxiliary hydraulic supply device, 25: Hydraulic circuit, 60: Control device, CL: Friction engagement element, HC: Target engagement element, TC: Specific engagement element, H: Target gear, HV: Target control valve, VL: Control valve

Claims

1. An automatic transmission comprising: a transmission device that transmits the rotation of an input member driven by a power source to an output member at a gear ratio of one of several gear stages; and a control device that controls the transmission device, The transmission comprises a plurality of friction engagement elements and a plurality of control valves that control the engagement state of the plurality of friction engagement elements, wherein, depending on the engagement state of the plurality of friction engagement elements, one of the plurality of gear stages is formed, or a neutral state is set in which no driving force is transmitted between the input member and the output member. Among the multiple gear stages, the gear stage to be targeted is designated as the target gear stage. The friction engagement element that is engaged when forming the target gear shift and released in the neutral state is defined as the target engagement element. The control valve that controls the hydraulic pressure supplied to the target engagement element is designated as the target control valve. The aforementioned transmission device is A hydraulic power generation device that generates hydraulic pressure for engaging multiple friction engagement elements, A hydraulic circuit capable of switching the hydraulic supply path from the hydraulic power generation device to each of the multiple control valves, When the hydraulic circuit is in a state where hydraulic pressure from the hydraulic pressure generating device is not supplied to the target control valve, an auxiliary hydraulic pressure supply device is provided to supply hydraulic pressure to the target control valve, Equipped with, Automatic transmission, wherein the control device performs fail-safe control by prohibiting the supply of hydraulic pressure by the auxiliary hydraulic supply device if a specific failure occurs in the control valve, such that the target engaging element transmits driving force to the output member, even though the control valves are controlled to put the transmission in the neutral state.

2. The automatic transmission according to claim 1, wherein the specified failure is a failure in which a specified engaging element, which is an engaging element that forms any of the gear stages in combination with the target engaging element, becomes engaged.

3. The automatic transmission according to claim 2, wherein the control device determines that a specific malfunction has occurred when the control valve that supplies hydraulic pressure to the specific engagement element is malfunctioning, or when the gear shifts formed by the specific engagement element being in a disengaged state are not properly formed.

4. The automatic transmission according to any one of claims 1 to 3, wherein the control device terminates the fail-safe control and permits hydraulic supply by the auxiliary hydraulic supply device when the power supply from the vehicle power source is interrupted and then resumed.

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