JP7183557B2 - Vehicle drive system - Google Patents

Description

The present invention relates to a vehicle drive system having an oil pump driven by a power source.

Generally, a vehicle equipped with an engine and an automatic transmission is provided with a mechanical oil pump that is driven by rotation of the engine. While the engine is running, hydraulic pressure generated by the oil pump is selectively supplied to hydraulic chambers of a plurality of frictional engagement elements forming a transmission mechanism via a transmission control circuit. As a result, in the automatic transmission, a plurality of frictional engagement elements are selectively engaged to form a gear stage according to the driving state of the vehicle.

In addition, the oil discharged from the oil pump is supplied to the lubricated parts such as the meshing parts of the gears and the cooled parts such as the friction plates of the frictional engagement elements via the lubrication system circuit. Lubrication and cooling of each part in the transmission case are achieved.

Various documents including Japanese Patent Laid-Open No. 2002-200010 disclose a vehicle drive system having an oil pump of this type. In the configuration of Patent Document 1, the oil discharged from the oil pump accumulates pressure in the accumulator during an upshift, and the oil is supplied from the accumulator to the suction portion of the oil pump during a downshift. It functions as an oil motor that adds torque to the engine.

JP 2017-154690 A

As shown in FIG. 16, the power W1 performed by the above-described oil pump in the shift control circuit is a value (P1×Q1 ). Generally, the hydraulic pressure P1 supplied to the shift control circuit is significantly higher than the hydraulic pressure P2 supplied to the lubrication system circuit.

On the other hand, the power W2 that the oil pump performs in the lubrication system circuit is the value obtained by multiplying the oil pressure P2 required for oil to reach the parts to be lubricated and the parts to be cooled by the oil supply flow rate Q2 to the lubrication system circuit (P2× Q2). Normally, the oil flow Q2 supplied to the lubrication system circuit is significantly larger than the oil flow Q1 supplied to the shift control circuit.

As described above, the oil pump, which is used both for gear shift control and lubrication, pumps oil at a high pressure higher than the oil pressure P1 required by the gear shift control circuit and at a large flow rate (Q1 + Q2) or higher required by the lubricating system circuit and the gear shift control circuit. Need to spit. That is, the oil pump must operate at least at a power W0 (=P1×(Q1+Q2)) obtained by multiplying the discharge pressure P1 by the discharge flow rate (Q1+Q2).

However, as described above, the power W1 performed by the oil pump in the shift control circuit and the power W2 performed in the lubricating system circuit are only a small portion of the total power W0. The inventors of the present application focused on this point and found that the current work of the oil pump is wasteful, and a large load is applied to the engine, which adversely affects the fuel efficiency performance.

It is also conceivable to reduce the power of each oil pump by installing an oil pump dedicated to lubrication and an oil pump dedicated to shift control, but in this case, the number of parts and weight will increase. , complicates the structure, and lowers the degree of freedom in layout. In particular, if one of the oil pumps is electrically driven, an expensive electric motor is required to drive it.

Accordingly, the present invention provides a vehicle drive system in which an oil pump driven by a power source of the vehicle is used both for gear shift control and lubrication, wherein the load on the power source can be reduced by reducing the power of the oil pump. An object of the present invention is to provide a driving device for a vehicle.

In order to solve the above problems, a vehicle drive system according to the present invention is characterized by the following configuration.

The invention described in claim 1 of the present application is
a power source that generates power for running the vehicle;
an oil pump driven by the power source;
an automatic transmission that speeds and transmits the output of the power source to the wheels;
lubricating means for supplying oil to at least one of a lubricated portion and a cooled portion of the automatic transmission;
a pressure accumulator that is pressure-accumulated by the oil discharged from the oil pump;
a check valve switchable between a closed state that maintains the hydraulic pressure stored in the pressure accumulator and an open state that allows both pressure accumulation in the pressure accumulator and release of oil from the pressure accumulator;
switching means for selectively connecting the discharge portion of the oil pump to the lubricating means or the pressure accumulator;
The check valve is closed and the discharge portion is connected to the lubricating means when the gear is not being shifted, and the check valve is opened when the gear is being shifted to perform an upshift. switching control means for controlling the switching means to connect the discharge portion to the pressure accumulator when the
and shift control means for controlling the shift of the automatic transmission using the hydraulic pressure stored in the pressure accumulator.

The invention according to claim 2 is the invention according to claim 1,
The shift control means includes a hydraulic chamber to which hydraulic pressure is supplied for engaging the frictional engagement elements of the automatic transmission, and sealing means for sealing the hydraulic chamber in the engaged state of the frictional engagement elements. characterized by

The invention according to claim 3 is the invention according to claim 2,
The friction engagement element includes a plurality of friction plates that are fastened by pressing, a pressing member that presses the plurality of friction plates, and a hydraulic chamber forming member that forms the hydraulic chamber between itself and the pressing member,
The pressing member and the hydraulic chamber forming member are non-rotating members whose rotation with respect to the transmission case is restricted.

The term "pressing member" used herein includes a piston that directly presses the friction plate and a member that indirectly presses the friction plate via the piston.

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
The switching control means controls the switching means so as to connect the discharge portion to the lubricating means when a downshift is being performed.

The invention according to claim 5 is the invention according to any one of claims 1 to 4,
The pressure accumulator is provided so as to be connectable to the suction portion of the oil pump via the switching means,
The switching control means controls the switching means so as to connect the pressure accumulator to the suction portion when a downshift is being performed.

According to the first aspect of the invention, the oil discharged from the oil pump is exclusively supplied to the lubricating means and is not supplied to the shift control means when the gear is not shifted, so that the discharge pressure of the oil pump can be reduced. can. On the other hand, during shifting, the hydraulic pressure accumulated in the pressure accumulator is used as the high hydraulic pressure required for shift control. The hydraulic pressure accumulated in this pressure accumulator is supplied by energy for reducing the number of revolutions of the power source during upshifting. Conventionally, the energy that lowers the rotation speed was dissipated and discarded as frictional heat of frictional engagement elements. , the load on the power source can be reduced, and the fuel efficiency can be improved.

In addition, since one oil pump can be used for both lubrication and shift control, the number of parts can be reduced, the structure can be simplified, and the layout can be freely arranged compared to the case where an oil pump dedicated to lubrication and an oil pump dedicated to shift control are used together. It is advantageous in terms of measuring degree. Since pressure accumulation in the pressure accumulator can also be used for hydraulic control during idling stop, there is an advantage that the electric oil pump for idling stop can be reduced.

Furthermore, during an upshift, pressure is accumulated in the pressure accumulator, which increases the load on the oil pump, thereby promoting a decrease in the rotation speed of the power source. Therefore, the rotation speed of the power source can be quickly reduced to a value corresponding to the gear ratio after the upshift, thereby shortening the time required for the upshift.

According to the second aspect of the present invention, the hydraulic chamber corresponding to the engaged frictional engagement element is sealed during non-shifting. The engaged state of the friction engagement element can be maintained. In addition, since the pressure accumulator only needs to store enough oil to be supplied to the hydraulic chamber only during shifting, the capacity of the pressure accumulator can be reduced.

According to the third aspect of the invention, since the pressing member and the hydraulic chamber forming member that form the hydraulic chamber of the frictional engagement element are non-rotating members, a seal is interposed between the pressing member and the hydraulic chamber forming member. It becomes easier to reliably bring the member into close contact with both members. Therefore, the sealed state of the hydraulic chamber by the sealing means can be maintained satisfactorily.

According to the fourth aspect of the present invention, it is possible to continue supplying oil to the lubricating means while performing shift control using the pressure accumulated in the pressure accumulator at the time of downshifting. In addition, during downshifting, shift control is performed using pressure accumulated in the pressure accumulator, and pressure accumulation from the oil pump to the pressure accumulator is regulated, thereby reducing the load on the oil pump and the power source compared to when upshifting. can be effectively reduced. Therefore, during the downshift, the rate of increase in the rotational speed of the power source is suppressed from decreasing, so that the downshift can be completed quickly.

According to the fifth aspect of the invention, when downshifting, the pressure accumulated in the pressure accumulator can be used not only for downshift control but also for operating the oil pump as an oil motor. Therefore, the oil motor can assist the increase in the rotational speed of the power source due to the downshift, thereby effectively shortening the time required for the downshift.

1 is a schematic configuration diagram showing a vehicle drive system according to an embodiment of the present invention; FIG. 1 is a hydraulic circuit diagram showing an example of a hydraulic control device; FIG. FIG. 2 is a hydraulic circuit diagram showing part of a shift control circuit; 4 is a flowchart showing the flow of control operations of the hydraulic control device; FIG. 3 is a hydraulic circuit diagram similar to FIG. 2 showing the flow of oil during non-shifting; FIG. 3 is a hydraulic circuit diagram similar to FIG. 2 showing oil flow during an upshift; FIG. 3 is a hydraulic circuit diagram similar to FIG. 2 showing oil flow during a downshift; 4 is a time chart showing an example of temporal changes in various elements due to upshifting; 4 is a time chart showing an example of temporal changes in various elements due to downshifting; The hydraulic circuit diagram which shows the modification of a hydraulic-control apparatus. FIG. 11 is a flow chart showing the flow of the control operation of the hydraulic control device shown in FIG. 10; FIG. FIG. 11 is a hydraulic circuit diagram similar to FIG. 10 showing the flow of oil during non-shifting; FIG. 11 is a hydraulic circuit diagram similar to FIG. 10 showing oil flow during an upshift; FIG. 11 is a hydraulic circuit diagram similar to FIG. 10 showing oil flow during a downshift; A time chart showing an example of temporal changes in various elements due to downshifting in a modified example. The figure for demonstrating the power of an oil pump.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a vehicle drive system according to the present invention will be described with reference to the accompanying drawings.

[overall structure]
As shown in FIG. 1, the vehicle drive system 1 according to the present embodiment includes an engine 2 as a power source that generates power for running the vehicle, and an output of the engine 2 that is changed and transmitted to the drive wheels. and an automatic transmission 10 that

The engine 2 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine. The output of engine 2 is output at crankshaft 3 . An input shaft 9 of the automatic transmission 10 is connected to the crankshaft 3 via a clutch 6, for example, so that it can be connected and disconnected. Clutch 6 is basically engaged while the vehicle is running, and gear shifting of automatic transmission 10 is performed in the engaged state of clutch 6 . The crankshaft 3 is provided with a damper 4 for reducing shock during shifting.

When the engine 2 is idling stopped while the vehicle is running, the clutch 6 may be released even while the vehicle is running. A torque converter may be provided between the crankshaft 3 of the engine 2 and the input shaft 9 of the automatic transmission 10 instead of the damper 4 and the clutch 6 .

A mechanical oil pump 8 driven by the engine 2 when the clutch 6 is engaged is provided on the input shaft 9 of the automatic transmission 10 . The oil pump 8 is driven by rotation of the input shaft 9 . The oil pump 8 is driven by the rotation of the engine 2 when the engine 2 is driven and the clutch 6 is engaged, and is driven by the rotation of the driving wheels when the clutch 6 is released while the vehicle is running. The hydraulic pressure generated by the oil pump 8 is used by a hydraulic control device 40 for controlling the automatic transmission 10 and the clutch 6 .

The automatic transmission 10 includes a speed change mechanism (not shown) provided on the input shaft 9 and a transmission case (not shown) that houses the speed change mechanism. 2) are provided. The automatic transmission 10 is, for example, a stepped transmission provided with a plurality of friction engagement elements 20 (see FIG. 3) for switching power transmission paths. The plurality of frictional engagement elements 20 are selectively engaged by hydraulic control by the hydraulic control device 40, thereby forming each gear stage.

[Hydraulic control device]
As shown in FIG. 2, the hydraulic control device 40 includes the oil pump 8 described above, and a lubrication system circuit 42 and a high pressure system circuit 44 to which the oil discharged from the oil pump 8 is selectively supplied. .

The oil pump 8 is, for example, a gear pump. An output line 50 is connected to the discharge portion of the oil pump 8 . While the engine 2 is running, the oil pump 8 sucks the oil stored in the oil pan 38 from the suction portion and discharges it from the discharge portion to the output line 50 .

The oil pump 8 is preferably of a variable displacement type. In this case, oil pressure feedback may be performed to stabilize the discharge pressure of the oil pump 8 . However, the oil pump 8 may be of a fixed capacity type.

A downstream end of the output line 50 is branched via a circuit switching valve 46 into a lubrication line 51 that is the input portion of the lubrication system circuit 42 and a high pressure line 52 that is the input portion of the high pressure system circuit. As a result, the discharge portion of the oil pump 8 can be selectively connected to either the lubrication system circuit 42 or the high pressure system circuit 44 via the circuit switching valve 46 .

In the lubrication system circuit 42 , the lubrication line 51 supplies oil to the lubricated parts such as the meshing parts (not shown) of the gears constituting the transmission mechanism and the parts to be cooled such as the friction plates 22 and 24 of the friction engagement element 20 . are branched into a plurality of oil passages (not shown) that guide the The oil supplied to the lubricated parts and the cooled parts from the plurality of oil passages of the lubrication system circuit 42 is returned to the oil pan 38 .

In the high-pressure system circuit 44 , an accumulator 48 is connected to the downstream end of the high-pressure line 52 via a first pilot check valve 58 . The first pilot check valve 58 permits oil flow in the direction from the upstream side (oil pump 8 side) to the downstream side (accumulator 48 side) based on a hydraulic signal, for example, and regulates the reverse oil flow. 5) and an open state (shown in FIGS. 6 and 7) that allows oil to flow in both directions.

When the first pilot check valve 58 is closed, the accumulator 48 can take in and hold the oil supplied via the high pressure line 52 , thereby allowing pressure to be accumulated in the accumulator 48 . When the first pilot check valve 58 is open, it is possible to accumulate pressure in the accumulator 48 and release oil from the accumulator 48 .

A main line 53 that is an input portion of a shift control circuit 55 is connected to the high pressure line 52 at a portion between the circuit switching valve 46 and the first pilot check valve 58 . The shift control circuit 55 performs hydraulic control for selectively engaging the plurality of frictional engagement elements 20 .

[Transmission control circuit]
As shown in FIG. 3, the shift control circuit 55 includes a hydraulic chamber 30 to which hydraulic pressure for engagement is supplied for each frictional engagement element 20, and an engagement control circuit section 60 that controls the supply and discharge of oil to and from the hydraulic chamber 30. It has

In the example shown in FIG. 3 , the friction engagement element 20 is a clutch that disconnectably connects the first power transmission member 21 and the second power transmission member 23 that constitute the transmission mechanism of the automatic transmission 10 . Each of the first power transmission member 21 and the second power transmission member 23 is a rotating member provided rotatably around the axis of the input shaft 9 .

The clutch 20 includes at least one first friction plate 22 engaged with the inner peripheral surface of the tubular portion of the first power transmission member 21, and engaged with the outer peripheral surface of the tubular portion of the second power transmission member 23. and at least one second friction plate 24 and a piston 26 that presses the first friction plate 22 and the second friction plate 24 .

The first friction plates 22 and the second friction plates 24 are arranged alternately in the axial direction. The piston 26 is supported by, for example, the first power transmission member 21 so as to be rotatable about the axis of the input shaft 9 and slidable in the axial direction. By sliding in the axial direction, the piston 26 axially presses the first friction plate 22 and the second friction plate 24 to fasten them together. The sliding of the piston 26 is controlled by supplying and discharging oil to the hydraulic chamber 30 .

Clutch 20 shown in FIG. The pressing member 31 and the hydraulic chamber forming member 32 are non-rotating members whose rotation with respect to the transmission case is restricted. The pressing member 31 is a member separate from the transmission case. The hydraulic chamber forming member 32 may be a member separate from the transmission case, or may be integrated with the transmission case.

The pressing member 31 rotatably supports the piston 26 via a bearing 33 on the side opposite to the hydraulic chamber 30 in the axial direction. The pressing member 31 is provided so as to be slidable in the axial direction according to the supply and discharge of oil to the hydraulic chamber 30 . A sealing member 34 is interposed between the pressing member 31 and the hydraulic chamber forming member 32 to keep the hydraulic chamber 30 oil-tight while allowing the pressing member 31 to move relative to the hydraulic chamber forming member 32 . . The sealing member 34 is, for example, an O-ring made of rubber.

Since the pressing member 31 and the hydraulic chamber forming member 32 are non-rotating members, the sealing member 34 only needs to allow relative movement between the two members 31 and 32 in the axial direction, and does not need to allow relative rotation. Therefore, the sealing member 34 can apply a relatively strong pressing force to both the members 31 and 32, thereby ensuring high sealing performance.

The engagement control circuit unit 60 includes a linear solenoid valve 64 as a hydraulic control valve that controls hydraulic pressure supplied to the hydraulic chamber 30 . An input portion of the linear solenoid valve 64 is connected through an input line 61 to the main line 53 (see FIG. 2). An output line 62 is connected to the output of the linear solenoid valve 64 .

The linear solenoid valve 64 discharges oil to the output line 62 at a flow rate corresponding to its opening. Of the oil supplied to the linear solenoid valve 64 from the input line 61 , the remaining oil other than the oil discharged to the output line 62 is returned to the oil pan 38 via the drain line 63 .

A downstream end of the output line 62 is connected to the hydraulic chamber 30 via a second pilot check valve 66 . The second pilot check valve 66 allows oil to flow in a direction from the upstream side (linear solenoid valve 64 side) to the downstream side (hydraulic chamber 30 side) based on, for example, a hydraulic pressure signal, and allows oil to flow in the opposite direction. can be switched between a closed state that restricts the oil flow and an open state that allows oil flow in both directions.

The hydraulic chamber 30 can be sealed by the sealing member 34 and the closed second pilot check valve 66 . Therefore, while the second pilot check valve 66 is closed, the hydraulic pressure supplied to the hydraulic chamber 30 can be maintained. Hydraulic pressure can be supplied to the hydraulic chamber 30 whether the second pilot check valve 66 is open or closed. Drainage of oil from the hydraulic chamber 30 is possible when the second pilot check valve 66 is open.

When hydraulic pressure is supplied to the hydraulic chamber 30 , the pressing member 31 slides together with the piston 26 in the direction of pressing the friction plates 22 and 24 (fastening direction). Thereby, the friction plates 22 and 24 can be pressed and fastened by the piston 26 . Once the friction plates 22 and 24 are fastened, the fastened state of the friction plates 22 and 24 is maintained as long as the hydraulic pressure in the hydraulic chamber 30 is maintained by the closed second pilot check valve 66 .

When the hydraulic pressure in the hydraulic chamber 30 decreases while the second pilot check valve 66 is open, the piston 26 and the pressing member 31 move away from the friction plates 22 and 24 ( release direction), thereby releasing the friction plates 22,24.

Although FIG. 3 shows an example in which the frictional engagement element 20 is a clutch, a brake that connects a rotating member (rotating element) and a non-rotating member (stationary element) basically has the same hydraulic pressure. A chamber 30 and an engagement control circuit portion 60 are provided. However, in the brake, the piston that directly presses the friction plate may be a non-rotating member, and the pressing member 31 may be used as the piston.

[Control system]
Returning to FIG. 1, hydraulic control device 40 is controlled by an electrical signal from control device 80 . The control device 80 is mainly composed of, for example, a microprocessor. The controller 80 includes a central processing unit (CPU), memory including RAM and ROM, and an input/output interface circuit.

The control device 80 includes, for example, a vehicle speed sensor 81 that detects the speed of the vehicle, an accelerator opening sensor 82 that detects the amount of depression of the accelerator pedal (accelerator opening), a brake switch 83 that detects the depression of the brake pedal, an automatic gear shift Signals from a range sensor 84 that detects the shift range of the machine 10 and an engine speed sensor 85 that detects the speed of the engine 2 are input.

In addition to these, signals from various devices such as an oil temperature sensor that detects the temperature of hydraulic oil used in the hydraulic control device 40 may be input to the control device 80 .

The control device 80 outputs control signals to the hydraulic control device 40 based on various input signals to control the automatic transmission 10 . In the shift control, for example, the target shift stage is determined based on the vehicle speed detected by the vehicle speed sensor 81, the accelerator opening detected by the accelerator opening sensor 82, and a predetermined shift map.

When shifting to the target shift speed, the engagement control circuit section 60 corresponding to each of the disengagement-side friction engagement element 20 and the engagement-side frictional engagement element 20 to be switched is controlled.

Specifically, referring to FIG. 3, in the disengagement-side frictional engagement element 20 that was engaged at the start of the gear shift, the second pilot check valve 66 is opened so that the hydraulic pressure in the hydraulic chamber 30 is reduced. The friction engagement element 20 is released by controlling the linear solenoid valve 64 at . On the other hand, the frictional engagement element 20 on the engagement side, which was released at the start of the shift, is engaged by controlling the linear solenoid valve 64 so that the engagement hydraulic pressure increases. It should be noted that the second pilot check valve 66 may be in an open state or in a closed state while such engagement control is being performed.

[Control action]
A specific example of the control operation of the hydraulic control device 40 will be described mainly with reference to the flowchart shown in FIG. 4 and also with reference to the hydraulic circuit diagrams shown in FIGS. 3 and 5 to 7 as appropriate.

As shown in FIG. 4, first, in step S1, it is determined whether or not the automatic transmission 10 is shifting gears.

As a result of the determination in step S1, if the shift is not in progress, the first pilot check valve 58 of the high-pressure system circuit 44 is closed in step S2 (see FIG. 5). Thereby, the hydraulic pressure stored in the accumulator 48 is maintained.

Further, in step S2, the second pilot check valves 66 (see FIG. 3) are closed in the engagement control circuit units 60 corresponding to all the frictional engagement elements 20, whereby the hydraulic pressure chambers of the respective frictional engagement elements 20 A hydraulic pressure of 30 is maintained. Therefore, in the frictional engagement element 20 in the engaged state, the engaged state is maintained even if the hydraulic pressure supply to the hydraulic chamber 30 is not continued.

Furthermore, during non-shifting, in step S3, the circuit switching valve 46 is controlled so that the output line 50 of the oil pump 8 is connected to the lubrication line 51 (see FIG. 5). As a result, the oil discharged from the oil pump 8 is supplied to the parts to be lubricated and the parts to be cooled of the automatic transmission 10 via the lubrication system circuit 42 during non-shifting.

On the other hand, if the automatic transmission 10 is shifting gears as a result of the determination in step S1, the first pilot check valve 58 of the high-pressure system circuit 44 is opened in step S4 (see FIGS. 6 and 7). As a result, hydraulic pressure can be supplied from the accumulator 48 to the shift control circuit 55 .

Further, in step S4, the second pilot check valve 66 (see FIG. 3) is opened in the engagement control circuit section 60 corresponding to each of the frictional engagement elements 20 on the disengagement side and the engagement side that are switched for gear shifting. This allows the oil to be drained from the hydraulic chamber 30 . Therefore, disengagement is promoted in the frictional engagement element 20 on the disengagement side, and the hydraulic pressure in the hydraulic chamber 30 is appropriately suppressed in the frictional engagement element 20 on the engagement side.

Further, in step S4, the second pilot check valve 66 is kept closed in the engagement control circuit section 60 corresponding to each frictional engagement element 20 that is not replaced. In step S4, the second pilot check valve 66 may also be kept closed in the engagement control circuit section 60 corresponding to the frictional engagement element 20 on the engagement side.

In the subsequent step S5, it is determined whether the shift corresponds to an upshift or a downshift.

If the result of determination in step S5 is an upshift, in step S6 the circuit switching valve 46 is controlled so that the output line 50 of the oil pump 8 is connected to the high pressure line 52 (see FIG. 6). As a result, the oil discharged from the oil pump 8 is supplied to the high-pressure system circuit 44 during the upshift.

During upshifting, in the high-pressure system circuit 44 , oil is supplied from the oil pump 8 to the accumulator 48 , allowing pressure to be accumulated in the accumulator 48 . Also, in parallel with the accumulation of pressure in the accumulator 48, oil can be supplied from at least one of the accumulator 48 and the oil pump 8 to the shift control circuit 55, thereby enabling shift control in the shift control circuit 55. .

In the subsequent step S7, the above-described engagement control and release control are performed in the engagement control circuit section 60 (see FIG. 3) corresponding to each of the disengagement side and engagement side frictional engagement elements 20 to be switched for upshifting. . In step S7, the engagement control uses the oil supplied to the shift control circuit 55 from at least one of the accumulator 48 and the oil pump 8 as described above.

Of the oil supplied to the shift control circuit 55, surplus oil not used in engagement control and oil discharged from the hydraulic chamber 30 of the friction engagement element 20 on the disengagement side due to disengagement control flow through the drain line 63. It is returned to the oil pan 38 via.

On the other hand, if the result of determination in step S5 is a downshift, the circuit switching valve 46 is controlled in step S8 so that the output line 50 of the oil pump 8 is connected to the lubrication line 51 (see FIG. 7). . As a result, oil supply to the parts to be lubricated and the parts to be cooled via the lubrication system circuit 42 can be continued during the downshift.

Further, during the downshift, the high-pressure system circuit 44 allows hydraulic pressure to be supplied from the accumulator 48 to the shift control circuit 55 . As a result, the hydraulic pressure stored in the accumulator 48 during upshifting can be used to control the hydraulic pressure for downshifting.

In the following step S9, the engagement control circuit section 60 (see FIG. 3) corresponding to each of the disengagement-side and engagement-side frictional engagement elements 20 to be switched for downshifting performs engagement control or disengagement control in the same manner as described above. done.

[Example of upshift operation]
With reference to the time chart shown in FIG. 8, a specific example of changes over time in various operations in the case of upshifting from a predetermined gear stage to a gear stage higher by at least one stage while the vehicle is running will be described.

In the example shown in FIG. 8, the oil discharged from the oil pump 8 is used exclusively in the lubricating system circuit 42 (see FIG. 5) in the non-shifting state until time t1, so that the high-pressure system circuit 44 is supplied with hydraulic pressure. you don't have to. As a result, the discharge pressure of the oil pump 8 is reduced. Therefore, as shown in FIG. 8(g), the load torque G1 of the oil pump 8 is reduced compared to the load torque G2 when oil is constantly supplied to both the shift control circuit and the lubrication system circuit as in the conventional art. can.

During the upshift from time t1 to time t4, the discharge part of the oil pump 8 is connected to the high-pressure circuit 44 (see step S6 in FIG. 4 and FIG. 8B), and the first pilot check of the high-pressure circuit 44 is performed. The valve 58 and the second pilot check valve 66 of each engagement control circuit unit 60 corresponding to the frictional engagement element 20 to be replaced are opened (step S4 in FIG. 4, FIG. 8(c), and FIG. 8(d)).

While the frictional engagement element 20 is replaced from time t2 to time t3, oil is supplied from at least one of the accumulator 48 and the oil pump 8 to the hydraulic chamber 30 of the frictional engagement element 20 on the engagement side (FIG. 8(h)). reference). During this time, the engine speed E1 gradually decreases (see FIG. 8(e)).

During the upshift, pressure is accumulated from the oil pump 8 to the accumulator 48 (see FIG. 8(i)), thereby increasing the load torque G1 of the oil pump 8 (see FIG. 8(g)). Therefore, as shown by symbol E2 in FIG. 8(e), the engine speed E1 is quickly reduced to a value corresponding to the shift stage after the upshift, compared to the case where pressure accumulation in the accumulator 48 is not performed. As a result, the time required for upshifting can be shortened, and the hydraulic pressure accumulated in the accumulator 48 is supplied by energy that reduces the rotation speed of the power source during upshifting. Conventionally, the energy for lowering the rotation speed was radiated and discarded by frictional heat of the friction engagement element, etc. Therefore, by utilizing the energy, the power of the oil pump 8 can be effectively reduced. can.

Conventionally, in order to quickly reduce the rotation speed of the engine 2 during an upshift, the ignition timing of the engine 2 is retarded, etc., thereby increasing the torque of the engine 2 as indicated by F2 in FIG. 8(f). may decrease. In the present embodiment, such torque reduction of the engine 2 can be omitted, so deterioration of fuel efficiency performance due to an increase in the load torque G1 of the oil pump 8 can be suppressed.

[Example of downshift operation]
With reference to the time chart shown in FIG. 9, specific examples of changes over time in various operations when downshifting from a predetermined gear stage to a gear stage that is at least one gear lower than the predetermined gear stage while the vehicle is running will be described.

In the example shown in FIG. 9, during the downshift from time t11 to time t14, as in the upshift, the first pilot check valve 58 of the high-pressure system circuit 44 and each of the frictional engagement elements 20 that are to be replaced are engaged. The second pilot check valve 66 of the engagement control circuit section 60 is opened (step S4 in FIG. 4, see FIGS. 9(c) and 9(d)).

While the frictional engagement element 20 is replaced from time t12 to time t13, the pressure accumulated by the accumulator 48 is used to supply oil to the hydraulic chamber 30 of the frictional engagement element 20 on the engagement side (see FIG. 9(h)). (See FIG. 9(i)). During this period, the engine speed E1 gradually increases (see FIG. 9(e)).

During the downshift, the state in which the discharge portion of the oil pump 8 is connected to the lubricating system circuit 42 continues (see step S8 in FIG. 4 and FIG. 9B). Therefore, it is possible to perform a downshift using pressure accumulation in the accumulator 48 while continuing to lubricate and cool each part in the transmission case.

In addition, during the downshift, there is no need to accumulate pressure in the accumulator 48 or supply hydraulic pressure to the shift control circuit 55, so the load on the oil pump 8 and the engine 2 can be effectively reduced as in the non-shift operation. can be reduced (see FIG. 9(g)). Therefore, during the downshift, the rate of increase in the rotational speed of the engine 2 is suppressed from being lowered, thereby achieving prompt completion of the downshift.

As described above, according to the present embodiment, there is no need to supply hydraulic pressure to the high pressure system circuit 44 during non-shifting and downshifting. In addition, the accumulated pressure of the accumulator 48 is used to supply the hydraulic pressure to the hydraulic chamber 30 during the downshift and the upshift. Therefore, the oil pump 8 does not need to generate a high hydraulic pressure (see symbol P1 in FIG. 16) that is used for engagement control, and the hydraulic pressure accumulated in the accumulator 48 is used to rotate the power source during upshifting. Conventionally, the energy that lowers the rotational speed was dissipated by the frictional heat of frictional engagement elements. The power of the pump 8 can be effectively reduced.

Furthermore, after completion of engagement, the hydraulic chamber 30 is sealed by the closed second pilot check valve 66, so that the engaged state can be maintained even if the supply of hydraulic pressure to the hydraulic chamber 30 is stopped. Therefore, the discharge pressure of the oil pump 8 can be reduced to a low hydraulic pressure (see symbol P2 in FIG. 16) that allows oil to be supplied to the lubrication system circuit 42 .

In addition, since the oil discharged from the oil pump 8 is always supplied only to either the lubrication system circuit 42 or the high pressure system circuit 44, the discharge flow rate of the oil pump 8 can be effectively reduced.

Therefore, by reducing the discharge pressure and the discharge flow rate, the power of the oil pump 8 can be effectively reduced, thereby reducing the load on the engine 2 and improving the fuel efficiency.

Furthermore, since the hydraulic chamber 30 is closed during non-shifting, only a small amount of oil is supplied from the accumulator 48 to the hydraulic chamber 30 during shifting. Therefore, the amount of oil stored in the accumulator 48 can be reduced, and the capacity of the accumulator 48 can be reduced.

In addition, since one oil pump 8 can be used for both lubrication and shift control, the number of parts can be reduced, the structure can be simplified, and the layout can be reduced compared to the case where an oil pump dedicated to lubrication and an oil pump dedicated to shift control are used together. This is advantageous for increasing the degree of freedom.

Furthermore, since the oil stored in the accumulator 48 during upshifting can also be used for oil pressure control during idle stop, there is an advantage that the electric oil pump for idle stop can be reduced.

[Modification]
Hereinafter, the configuration of a hydraulic control device 100 according to a modification will be described with reference to FIGS. 10 to 15. FIG. In addition, in the modified example, description of the same configuration as that of the hydraulic control device 40 described above is omitted, and the same reference numerals are given in FIGS. 10 and 12 to 14 .

As shown in FIG. 10, the hydraulic control device 100 according to the modification has a function of the oil pump 8, a pump function driven by the engine 2 or drive wheels, and a motor that assists the rotation of the engine 2 (see FIG. 1). It has a function switching mechanism 101 for switching between functions.

The function switching mechanism 101 includes a suction switching valve 102 connected to the suction portion of the oil pump 8 and a discharge switching valve 103 connected to the discharge portion of the oil pump 8 . The suction switching valve 102 and the discharge switching valve 103 are connected to each other via a connection line 104 on which the oil pump 8 is provided.

The suction switching valve 102 is provided so that the input side end (upstream side end) of the connection line 104 can be connected to the pump input line 105 for guiding the oil from the oil pan 38 to the suction portion of the oil pump 8 . there is The discharge switching valve 103 connects the output side end (downstream side end) of the connection line 104 to the supply line 106 for supplying the oil discharged from the oil pump 8 to the lubrication system circuit 42 or the high pressure system circuit 44 . provided as possible.

The downstream end of the supply line 106 is connected to the circuit switching valve 46 described above. That is, the supply line 106 is selectively connected to either the lubrication system circuit 42 or the high pressure system circuit 44 via the circuit switching valve 46 . On the supply line 106, there is a check valve 110 that allows oil to flow in the direction from the upstream side (oil pump 8 side) to the downstream side (circuit switching valve 46 side) and regulates the oil flow in the opposite direction. is provided.

One end of a motor input line 107 for introducing oil from the accumulator 48 to the suction portion of the oil pump 8 is connected to the portion of the supply line 106 between the check valve 110 and the circuit switching valve 46 . The other end of the motor input line 107 can be connected to the connection line 104 via the suction switching valve 102 . That is, the suction switching valve 102 selectively connects the suction portion of the oil pump 8 to either the pump input line 105 or the motor input line 107 .

The hydraulic control device 100 also includes a drain line 108 that returns the oil discharged from the oil pump 8 to the oil pan 38 without supplying it to either the lubricating system circuit 42 or the high pressure system circuit 44 . The discharge switching valve 103 selectively connects the discharge portion of the oil pump 8 to either the supply line 106 or the drain line 108 .

Since other configurations of the hydraulic control device 100 are the same as those of the hydraulic control device 40 described above, detailed description thereof will be omitted. Various operations of the hydraulic control device 100 are controlled by the above-described control device 80 (see FIG. 1).

[Control operation of modified example]
A specific example of the control operation of the hydraulic control device 100 according to the modification will be described mainly with reference to the flowchart shown in FIG. 11 and also with reference to the hydraulic circuit diagrams shown in FIGS. .

As shown in FIG. 11, first, in step S11, it is determined whether or not the automatic transmission 10 is shifting gears.

As a result of the determination in step S11, if the shift is not in progress, the first pilot check valve 58 of the high-pressure system circuit 44 is closed in step S12 (see FIG. 12). Thereby, the hydraulic pressure stored in the accumulator 48 is maintained.

In step S12, the second pilot check valves 66 (see FIG. 3) are closed in the engagement control circuit units 60 corresponding to all the frictional engagement elements 20, thereby closing the hydraulic chambers of the frictional engagement elements 20. A hydraulic pressure of 30 is maintained. Therefore, in the frictional engagement element 20 in the engaged state, the engaged state is maintained even if the hydraulic pressure supply to the hydraulic chamber 30 is not continued.

Further, during non-shifting, in step S13, the suction switching valve 102 is controlled so that the input side of the connection line 104 is connected to the pump input line 105, and the output side of the connection line 104 is connected to the supply line 106. The discharge switching valve 103 is controlled so that the discharge switch valve 103 is controlled (see FIG. 12).

Further, in step S14, the circuit switching valve 46 is controlled so that the supply line 106 is connected to the lubrication line 51 (see FIG. 12). As a result, the oil discharged from the oil pump 8 is supplied to the parts to be lubricated and the parts to be cooled of the automatic transmission 10 via the lubrication system circuit 42 during non-shifting.

On the other hand, if the automatic transmission 10 is shifting gears as a result of the determination in step S11, the first pilot check valve 58 of the high-pressure circuit 44 is opened in step S15 (see FIGS. 13 and 14). As a result, hydraulic pressure can be supplied from the accumulator 48 to the shift control circuit 55 .

In step S15, the second pilot check valve 66 (see FIG. 3) is opened in the engagement control circuit section 60 corresponding to each of the frictional engagement elements 20 on the disengagement side and the engagement side that are switched for gear shifting. This allows the oil to be drained from the hydraulic chamber 30 . Therefore, disengagement is promoted in the frictional engagement element 20 on the disengagement side, and an excessive increase in hydraulic pressure in the hydraulic chamber 30 is suppressed in the frictional engagement element 20 on the engagement side.

Further, in step S15, the second pilot check valve 66 is kept closed in the engagement control circuit section 60 corresponding to each frictional engagement element 20 that is not replaced. In step S15, the second pilot check valve 66 may be kept closed also in the engagement control circuit section 60 corresponding to the frictional engagement element 20 on the engagement side.

In the subsequent step S16, it is determined whether the shift corresponds to an upshift or a downshift.

If the result of determination in step S16 is an upshift, in step S17, the suction switching valve 102 is controlled so that the input side of the connection line 104 is connected to the pump input line 105, as in non-shifting. The discharge switching valve 103 is controlled so that the output side of the connection line 104 is connected to the supply line 106 (see FIG. 13).

Further, in step S18, the circuit switching valve 46 is controlled so that the supply line 106 is connected to the high pressure line 52 (see FIG. 13). As a result, the oil discharged from the oil pump 8 is supplied to the high-pressure system circuit 44 during the upshift.

During upshifting, in the high-pressure system circuit 44 , oil is supplied from the oil pump 8 to the accumulator 48 , allowing pressure to be accumulated in the accumulator 48 . Also, in parallel with the accumulation of pressure in the accumulator 48, oil can be supplied from at least one of the accumulator 48 and the oil pump 8 to the shift control circuit 55, thereby enabling shift control in the shift control circuit 55. .

In the following step S19, the above-described engagement control and release control are performed in the engagement control circuit section 60 (see FIG. 3) corresponding to each of the frictional engagement elements 20 on the disengagement side and the engagement side to be switched for upshifting. . In step S19, the oil supplied to the shift control circuit 55 from at least one of the accumulator 48 and the oil pump 8 is used for engagement control as described above.

Of the oil supplied to the shift control circuit 55, surplus oil not used in engagement control and oil discharged from the hydraulic chamber 30 of the friction engagement element 20 on the disengagement side due to disengagement control flow through the drain line 63. It is returned to the oil pan 38 via.

On the other hand, if the result of determination in step S16 is a downshift, the circuit switching valve 46 is controlled in step S20 so that the high pressure line 52 is connected to the motor input line 107 (see FIG. 14).

Further, in step S21, the suction switching valve 102 is controlled so that the input side of the connection line 104 is connected to the motor input line 107, and the discharge switching is performed so that the output side of the connection line 104 is connected to the drain line 108. Valve 103 is controlled (see FIG. 14).

As a result, during the downshift, the hydraulic pressure stored in the accumulator 48 is supplied to the suction portion of the oil pump 8, so that the oil pump 8 can operate as an oil motor that applies torque to the engine 2. .

Further, during the downshift, the high-pressure system circuit 44 allows hydraulic pressure to be supplied from the accumulator 48 to the shift control circuit 55 . As a result, the hydraulic pressure stored in the accumulator 48 during upshifting can be used to control the hydraulic pressure for downshifting.

In the subsequent step S22, the engagement control circuit section 60 (see FIG. 3) corresponding to each of the disengagement side and engagement side frictional engagement elements 20 to be switched for downshifting performs engagement control or disengagement control in the same manner as described above. done.

[Example of downshift operation in modified example]
With reference to the time chart shown in FIG. 15, regarding the hydraulic control device 100 according to the modification, the time course of various operations in the case of downshifting from a predetermined gear stage to a gear stage that is at least one gear lower than the predetermined gear stage while the vehicle is running. A specific example of the change will be described.

In the example shown in FIG. 15, during the downshift from time t21 to time t24, the first pilot check valve 58 of the high pressure system circuit 44 and each engagement control circuit section 60 corresponding to the frictional engagement element 20 to be replaced. The second pilot check valve 66 is opened (see step S15 in FIG. 11, FIG. 15(e), and FIG. 15(f)).

While the frictional engagement element 20 is replaced from time t22 to time t23, the pressure accumulated by the accumulator 48 is used to supply oil to the hydraulic chamber 30 of the frictional engagement element 20 on the engagement side (see FIG. 15(j)). (See FIG. 15(k)). During this time, the engine speed G11 gradually increases (see FIG. 15(g)).

Further, during the downshift, the circuit switching valve 46 is controlled so that the high-pressure line 52 is connected to the motor input line 107 (step S20 in FIG. 11, see FIG. 15(b)). The suction switching valve 102 is controlled so that the motor input line 107 is connected to the side (see step S21 in FIG. 11 and FIG. 15(c)), and the output side of the connection line 104 is connected to the drain line 108. , the discharge switching valve 103 is controlled (see step S21 in FIG. 11 and FIG. 15(d)).

As a result, the pressure accumulated in the accumulator 48 can be used to operate the oil pump 8 as an oil motor. Therefore, compared to the engine speed G12 when the oil pump 8 is not operated as an oil motor, the rate of increase of the engine speed G11 increases. Therefore, the time required for downshifting can be effectively shortened.

Although the present invention has been described with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments.

For example, in the above-described embodiment, the vehicle drive system 1 including the stepped automatic transmission 10 has been described. machine.

As described above, according to the present invention, in a vehicle drive system in which an oil pump driven by a power source of a vehicle is used both for shift control and lubrication, the power source is reduced by reducing the power of the oil pump. Since it is possible to provide a vehicle driving device that can reduce the load, there is a possibility that it will be suitably used in the industrial field of manufacturing vehicles equipped with this type of driving device.

1 vehicle driving device 2 engine (power source)
8 oil pump 10 automatic transmission 20 friction engagement element 26 piston 30 hydraulic chamber 31 pressing member 32 hydraulic chamber forming member 34 sealing member 38 oil pan 40 hydraulic control device 42 lubrication system circuit (lubrication means)
44 high pressure system circuit 46 circuit switching valve (switching means)
48 Accumulator
55 shift control circuit (shift control means)
58 First pilot check valve 66 Second pilot check valve (sealing means)
80 control device (switching control means)
100 Hydraulic Control Device 101 Function Switching Mechanism 102 Suction Switching Valve 103 Discharge Switching Valve

Claims (5)

a power source that generates power for running the vehicle;
an oil pump driven by the power source;
an automatic transmission that speeds and transmits the output of the power source to the wheels;
lubricating means for supplying oil to at least one of a lubricated portion and a cooled portion of the automatic transmission;
a pressure accumulator that is pressure-accumulated by the oil discharged from the oil pump;
a check valve switchable between a closed state that maintains the hydraulic pressure stored in the pressure accumulator and an open state that allows both pressure accumulation in the pressure accumulator and release of oil from the pressure accumulator;
switching means for selectively connecting the discharge portion of the oil pump to the lubricating means or the pressure accumulator;
The check valve is closed and the discharge portion is connected to the lubricating means when the gear is not being shifted, and the check valve is opened when the gear is being shifted to perform an upshift. switching control means for controlling the switching means to connect the discharge portion to the pressure accumulator when the
and shift control means for controlling the shift of the automatic transmission using the hydraulic pressure stored in the pressure accumulator. The shift control means includes a hydraulic chamber supplied with hydraulic pressure for engaging the frictional engagement elements of the automatic transmission, and sealing means for sealing the hydraulic chamber in the engaged state of the frictional engagement elements. The vehicle drive system according to claim 1, characterized by: The friction engagement element includes a plurality of friction plates that are fastened by pressing, a pressing member that presses the plurality of friction plates, and a hydraulic chamber forming member that forms the hydraulic chamber between itself and the pressing member,
3. The vehicle drive system according to claim 2, wherein the pressing member and the hydraulic chamber forming member are non-rotating members whose rotation with respect to the transmission case is restricted. 4. The switching control means controls the switching means so as to connect the discharge portion to the lubricating means when a downshift is being performed. The vehicle driving device according to . The pressure accumulator is provided so as to be connectable to the suction portion of the oil pump via the switching means,
5. The switching control means controls the switching means so as to connect the pressure accumulator to the suction portion when a downshift is being performed. The vehicle driving device according to .

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