JP4534588B2 - Power transmission device for vehicle using fluid coupling - Google Patents

Description

  The present invention includes a fluid coupling (fluid coupling) between an engine and a transmission, and does not require complicated operation of a clutch by a vehicle driver when starting the vehicle. The present invention relates to a vehicular power transmission device that can smoothly start using slippage between turbines.

  The power transmission device for vehicles has various types of power transmission that are easy-drive by automating the operation of clutches or transmissions that transmit engine power to wheels to facilitate vehicle driving or reduce driver fatigue. There is a device. A typical example is a so-called AT vehicle using a power transmission device including a torque converter, which is a fluid transmission device, and a planetary gear mechanism. Some power transmission devices for easy driving use a parallel-shaft gear mechanism type transmission similar to a so-called manual vehicle, and this is combined with an automatic clutch, etc. There is a power transmission device that omits the clutch operation when switching the gears, and it is also used in commercial vehicles. There is also a power transmission device that uses an electronic control device and an actuator for operating a transmission instead of a driver operating a shift lever, and automatically switches the gear position according to the traveling state of the vehicle.

  Recently, in a vehicle equipped with a diesel engine, a power transmission device in which a fluid coupling is interposed between the engine and the transmission has been developed. Although a fluid coupling is a kind of fluid transmission device, unlike a torque converter, it does not have a stator vane and does not have a torque increasing function, but has a simpler structure than a torque converter. When a fluid coupling is interposed, particularly in a diesel engine having a large torque in a region where the engine speed is small, it is possible to start using the slip between the pump of the fluid coupling and the turbine when starting the vehicle. That is, a delicate clutch operation is not required when starting a manual vehicle, and a smooth start can be easily performed. At the same time, engine torque fluctuations during idling are absorbed, and vibration and noise are reduced. An example of a power transmission device in which a fluid coupling is provided between an engine and a transmission is described in Japanese Patent Application Laid-Open No. 2001-241546.

  With reference to FIG. 2 and FIG. 3, the power transmission device for vehicles provided with such a fluid coupling is demonstrated. FIG. 2 is a cross-sectional view showing a power transmission device from the crankshaft of the diesel engine to the transmission. A fluid coupling 2 is fastened to the rear of the crankshaft 1, and further in parallel via a wet multi-plate clutch 3. A transmission 4 having a shaft gear mechanism is connected. The fluid coupling 2 includes a pump 21 and a turbine 22 that can rotate independently of each other, and the casing 23 is filled with hydraulic oil. The fluid coupling pump 21 is integrally coupled to the crankshaft 1 of the diesel engine by a casing 23, a drive plate 11, and the like. Further, the output shaft 24 of the fluid coupling 2 is coupled to the turbine 22, and the input shaft hub portion 31 of the wet multi-plate clutch 3 is coupled to the other end of the output shaft 24 by spline fitting. The output shaft hub portion 32 of the wet multi-plate clutch 3 is also coupled to the input shaft 41 of the transmission 4 by spline fitting.

  When the diesel engine is started at the start of the vehicle, the pump 21 of the fluid coupling 2 starts to rotate integrally with the crankshaft 1 and feeds hydraulic oil to the turbine 22. As the rotational speed of the diesel engine increases, the flow rate of the hydraulic oil circulating from the pump 21 to the turbine 22 increases, and the torque acting on the turbine 22 increases. The wet multi-plate clutch 3 connected to the fluid coupling 2 is in an engaged state by the hydraulic pressure acting on the friction plate, except when the vehicle is shifting. Prior to the start of the vehicle, the transmission 4 is geared into the start stage, and the vehicle is stopped by the depression of the brake pedal. At this time, the turbine 22 is also stopped, but the turbine 22 starts rotating with the release of the brake pedal, and the vehicle starts through the wet multi-plate clutch 3 and the transmission 4. After the vehicle starts, the rotational speed of the diesel engine further increases, and the rotational speed of the turbine 22 increases accordingly. The slip of the fluid coupling 2 decreases with the passage of time after the start, and the rotational speed of the turbine 22 gradually increases while approaching the rotational speed of the pump 21 (the rotational speed of the diesel engine). The ratio of the turbine speed at the joint to the pump speed approaches one.

  As described above, when the fluid coupling 2 is used, the vehicle can smoothly start due to slippage between the pump 21 and the turbine 22. However, as long as there is slippage of the fluid coupling 2, the power transmission efficiency does not reach 100%, and the diesel engine consumes useless fuel accordingly. Therefore, when the vehicle starts and can normally travel, the function of the fluid coupling 2 may be stopped and the crankshaft 1 and the transmission 4 may be directly connected during low-speed traveling of, for example, about 20 km / h. Desirably, the fluid coupling 2 is provided with a lock-up clutch 25 that fastens the pump 21 and the turbine 22.

  The lock-up clutch 25 is placed opposite to the inner surface of the casing 23 that connects the crankshaft 1 and the pump 21, and includes a clutch disk 26 connected to the turbine 22 and a friction fading 27 provided on the front side thereof. Composed. The disconnection and engagement of the lock-up clutch 25 is controlled by switching the flow path in which the high-pressure hydraulic oil flows in the casing 23 of the fluid clutch 2. As shown also in FIG. 3, a trochoid pump 51 that pressurizes and sends hydraulic oil and a flow path switching valve 52 that switches the flow path of the hydraulic oil are attached. This flow path switching valve 52 is a lock-up clutch. It is controlled by the control device 70.

  The hydraulic oil pressurized by the trochoid pump 51 flows into the chamber 28 on the front surface of the clutch disk 26 from the passage at the center of the output shaft 24, and enters the chamber 29 on the rear surface through a narrow gap on the outer periphery of the clutch disk 26. When the flow path is such that it flows into the working chamber formed by the pump 21 and the turbine 22, the pressure in the front chamber 28 is higher than that in the rear chamber 29, so that the clutch disk 26 moves away from the casing 23 and locks up. The clutch 25 is disconnected. When the flow is reversed by the flow path switching valve 52, the pressure on the rear surface side of the clutch disk 26 is increased, the friction fading 27 is engaged with the inner surface of the casing 23, the lockup clutch 25 is fastened, and the pump of the fluid coupling 2 21 and the turbine 22 are directly connected. The flow path switching valve 52 is switched by a lockup clutch control device 70 that gradually changes the duty ratio of a pulse using a pilot valve so as to avoid a shock due to a sudden engagement of the lockup clutch 25. The detailed configuration and control method of the lockup clutch 25 and the like are described in the aforementioned patent publication.

  The operation of the vehicle power transmission device using a fluid coupling with a lock-up clutch at the time of starting will be described with reference to FIG. FIG. 8 shows changes in engine speed (pump speed of the fluid coupling) and turbine speed after the start of a vehicle equipped with a naturally aspirated diesel engine with a large displacement. When the vehicle is stopped, the engine rotates at about 500 rpm, which is the number of rotations during idling, and the wheels are stopped by the depression of the brake pedal, so the turbine rotation speed is zero. When the driver releases the brake pedal and depresses the accelerator pedal from this state, the turbine starts rotating and the vehicle starts.

  After the start, the turbine speed increases as the engine speed increases, and the speed of the vehicle gradually increases. When the engine speed reaches around 1500 rpm, which will be described later, which is the stall speed, the turbine speed of the fluid coupling approaches the engine speed, and the speed ratio, which is the ratio of both speeds, becomes around 0.8. When the engine speed becomes the stall speed, a command for fastening the lockup clutch is output from the control device, and the pump and the turbine are fastened according to the command (lockup). As a result, both of them rotate integrally, the subsequent fluid coupling slips, and the transmission efficiency becomes 100%.

Here, the stall rotation speed of the fluid coupling will be described with reference to FIG. When a fluid coupling with a certain size and torque capacity is combined with a naturally aspirated engine (NA engine) and the turbine speed of the fluid coupling is stopped to increase the engine speed, the pump connected to the engine is integrated. The acting load torque increases in a quadratic curve as the rotational speed increases. On the other hand, the output torque of a naturally aspirated engine has a flat characteristic as shown by a solid line in a diesel engine, in which the torque is substantially constant even when the rotational speed changes. Therefore, the engine output speed curve is balanced by the rotational speed at the point ● where the engine rated output torque curve intersects with the pump load torque curve, and the engine rotational speed does not increase beyond that. This balanced engine rotational speed is referred to as stall rotational speed.
JP 2001-241546 A

  As described above, in a vehicle equipped with a naturally aspirated engine, that is, an engine that does not perform supercharging, the lockup clutch is set to be engaged when the vehicle speed exceeds a predetermined value and the engine speed reaches the stall speed. For example, the connection of the lockup clutch and the acceleration of the vehicle after the start can be performed without any trouble. However, when a so-called turbo engine equipped with a turbocharger for supercharging for the purpose of improving engine output is combined with a fluid coupling, the rotational speed increases once the engine is started, and once reaches a substantially constant rotational speed. After that, it was found that the rotational speed gradually increased again, and a phenomenon of stabilization at a higher rotational speed occurred (see FIG. 5). This phenomenon is particularly noticeable in engines equipped with large-capacity turbochargers with a large increase in engine output, and there are multiple stall rotation speeds. "

  The two-stage stall is considered to be caused by the output characteristics of the turbo engine indicated by the broken line in FIG. That is, in the turbo engine, the turbocharger cannot exhibit sufficient capacity at the time of start-up, and since the pressure (boost) of air supplied to the engine cylinder is low, the engine output torque is also low, and the lowermost broken line in FIG. It becomes a characteristic. If it is combined with the same fluid coupling as in the case of a naturally aspirated engine, it is balanced once at the intersection of the lowermost broken line and the pump load torque curve (marked with a circle), and the increase in engine speed reaches its peak at that speed (Fig. 5 stall rotation speed of the first stage).

  As the engine exhaust gas volume increases, the turbocharger speed increases and the boost increases, so the engine output torque increases, and the balance point of the fluid coupling with the pump load torque moves in the direction of higher speed. . When the engine finally reaches the rated operating state and the boost by the turbocharger becomes the boost at the full load of the engine, the output characteristic becomes like the uppermost broken line, and again at the intersection of this and the pump load torque curve In balance, the engine speed no longer increases (the second stage stall speed in FIG. 5). On the other hand, the speed ratio, which is zero when the turbine is stopped, increases when it starts rotating, and the speed ratio becomes 0.5 to 0.6 when the engine speed reaches the first stage stall speed. Thereafter, the speed ratio continues to increase, and reaches about 0.8 when the engine output increases again. Thus, the speed ratio increases with an increase in the engine speed, and is substantially determined corresponding to the engine speed at the start.

  Since the two-stage stall characteristic is derived from the operation of the turbocharger, it becomes more prominent in an engine equipped with a large-capacity turbocharger with a large increase in engine output. Not limited to this, for example, an EGR that recirculates exhaust gas for the purpose of reducing NOx in the exhaust gas, and in an engine having a turbocharger, recirculates the exhaust gas at the middle load of the engine, and near the full load Then, since the reflux is stopped, the difference in engine output between when the engine is started and when the engine is fully loaded is large, and the two-stage stall characteristic becomes remarkable.

  It has also been clarified that when a fluid coupling with a lockup clutch is connected to such a turbo engine, there is a problem of optimizing the timing for fastening the lockup clutch after the vehicle starts. For example, as with a naturally aspirated engine, if the lockup command is output when the engine speed and the turbine speed are close to each other and the speed ratio is about 0.8, this point will increase the turbocharger output. This corresponds to the time when the boost increases. As a result, the engine output torque and the engine speed increase again, and the engagement of the lockup clutch becomes unstable. As a result, the time required for engagement becomes longer or the shock of engagement of the lockup clutch increases.

  FIG. 9 shows a change in engine speed and the like when a lockup is instructed when the speed ratio is 0.8 as described above by combining a turbocharger using a large-capacity turbocharger and a high-pressure turbocharger and a fluid coupling. However, the engine speed after the lockup command fluctuates significantly, it takes time to engage the lockup clutch, and the acceleration characteristics before and after the lockup clutch is engaged are deteriorated. It is shown.

In view of the above-described problems, an object of the present invention is to optimize the timing of lock-up clutch engagement after starting in a vehicle power transmission device that combines a turbo engine and a fluid coupling with a lock-up clutch. That is, the present invention
“A vehicle power transmission device in which a fluid coupling is connected to an engine equipped with a turbocharger ,
The fluid fitting can fastening a pump coupled to the crankshaft of the engine, a turbine coupled to the output shaft of said fluid coupling, and a lock-up clutch for fastening the said and the pump turbine, the lock-up clutch A lock-up clutch control device, and
When the vehicle is started , the vehicle power transmission device is started while the lockup clutch is disconnected and the pump and the turbine are slid, and the rotational speed of the engine and the output torque of the engine are determined by the pump. After reaching the stall speed of the first stage that balances with the load torque, it has the characteristic of increasing again as the output of the turbocharger increases ,
The lock-up clutch control device detects a speed ratio that is a ratio of the turbine speed to the pump speed, and when the speed ratio rises to a predetermined speed ratio corresponding to the first stage stall speed. , Is set to start the engagement of the lock-up clutch "
This is a vehicle power transmission device.

  According to a second aspect of the present invention, the lock-up clutch includes a clutch disk disposed in the casing of the fluid coupling and connected to the turbine. When the clutch is engaged, the hydraulic oil in the casing is provided. It is preferable that the clutch disc is pressed against the casing by the pressure.

In the present invention, in order to start the engagement of the lockup clutch when the speed ratio is the predetermined speed ratio , as described in claim 3, the lockup clutch control device includes an engine speed sensor and a turbine speed sensor. The speed ratio is calculated based on the detected value , and when the speed ratio is increased to the predetermined speed ratio , it can be set to output a command for engaging the lockup clutch.

According to a fourth aspect of the present invention, when the engine speed detected by the engine speed sensor increases to a speed corresponding to the predetermined speed ratio, the lockup clutch control device is configured to lock the clutch. It can also be set to output a fastening command.

  And as described in Claim 5, the power transmission device with a fluid coupling of this invention can be applied more suitably with respect to the diesel engine which performs turbo supercharging.

In a turbo engine equipped with a turbocharger, there is a delay in the operation of the turbocharger. Therefore, when combined with a fluid coupling, the above-described two-stage stall characteristic occurs, and the lock-up clutch is unstable. However, in the present invention, the control device for engaging the lock-up clutch has a predetermined speed ratio (0.7 or less) in which the speed ratio, which is the ratio of the turbine speed to the pump speed , corresponds to the first stage stall speed. ) , I.e., before the boost rises due to an increase in the output of the turbocharger, the lockup clutch is set to be engaged. Thus, the engagement of the lockup clutch can be completed before the engine speed and the output torque increase as the boost increases.

  Normally, at the time of starting, the driver greatly depresses the accelerator pedal.After the delay period of the turbocharger operation, the engine becomes high output and the output torque and the rotational speed increase. At this time, the lock-up clutch is not engaged. In the present invention, the engagement of the lock-up clutch is started when the first stage stall occurs and the change in the engine speed is small. Therefore, it does not take a long time to engage the lockup clutch, and it is possible to suppress a shock at the time of engagement. When the boost increases due to the higher output of the turbocharger and the engine becomes high output, the lockup clutch is engaged and the engine is directly connected to the transmission, so the vehicle becomes smooth as the engine output increases. To be accelerated.

In the present invention, since the engagement of the lock-up clutch is started when the speed ratio is a predetermined speed ratio (0.7 or less) corresponding to the first stage stall speed , the turbine speed and the pump speed at this time The difference is relatively large. According to a second aspect of the present invention, the lock-up clutch has a clutch disk disposed in the casing of the fluid coupling and connected to the turbine. When the lock-up clutch is engaged, the clutch disk is caused by the pressure of the hydraulic oil in the casing. Is configured to be pressed against the casing, the fastening shock at the time of fastening can be mitigated based on the buffering action of the hydraulic oil.

  The vehicle power transmission device is equipped with an engine speed sensor and a turbine speed sensor in order to perform the control. According to the third aspect of the present invention, if a speed ratio is calculated based on detection values of these sensors and a lockup clutch engagement command is output, a special sensor or the like is not required. Control can be executed. Further, since the speed ratio is substantially determined by the engine speed, when only the detected value of the engine speed sensor is used as in claim 4, the control of the present invention can be executed with a much simpler configuration. Become.

  The diesel engine has a characteristic that the torque at the time of low engine rotation is large. Therefore, as described in claim 5, the power transmission device with a fluid coupling of the present invention can be more suitably applied to a diesel engine that performs turbocharging.

  Hereinafter, a vehicle power transmission device with a fluid coupling embodying the present invention will be described with reference to the drawings. FIG. 1 schematically shows a vehicle power transmission device of the present invention including a diesel engine 61. The diesel engine 61 is equipped with a turbocharger 62 for supercharging, and the turbocharger 62 has a compressor 621 for compressing air supplied to the engine cylinder and a compressor drive turbine 622 connected thereto. The pressure (boost) of the air compressed by the compressor 621 increases and is supplied from the intake pipe 63 to the cylinder. The exhaust gas after burning in the cylinder flows into the compressor drive turbine 622 through the exhaust pipe 64 and rotationally drives it. The diesel engine is provided with an EGR passage 65 that recirculates the exhaust gas to the intake pipe 63 in order to reduce NOx in the exhaust gas.

  The power of the diesel engine 61 is transmitted from the crankshaft 1 to the fluid coupling 2. The equipment constituting the vehicle power transmission device with a fluid coupling to which the present invention is applied differs from the conventional device shown in FIG. 2 except that the diesel engine 61 is a turbo engine provided with a turbocharger 62. It is not a thing. That is, a transmission 4 having a parallel shaft gear mechanism is connected to the rear of the fluid coupling 2 via a wet multi-plate clutch 3 that is a clutch that automatically connects and disconnects. The pump 21 of the fluid coupling 2 is integrally coupled to the crankshaft 1 by a casing 23 or the like, and the turbine 22 rotates integrally with the input shaft of the wet multi-plate clutch 3. The wet multi-plate clutch 3 is in an engaged state except during gear shifting, and the turbine 22 is directly connected to the input shaft 41 of the transmission.

  The fluid coupling 2 has a lock-up clutch 25 that fastens the pump 21 and the turbine 22. The configuration of the lockup clutch 25 and its control method are the same as those of the conventional device of FIG. 2, and a lockup clutch control device 70 is provided for controlling the engagement and disconnection of the lockup clutch 25. In response to the command, the flow of the hydraulic oil in the casing 23 pumped from the trochoid pump 51 is switched by the flow path switching valve 52 so that the clutch disk 26 connected to the turbine 22 is pressed against the inner surface of the casing 23. If it is a flow path, the lockup clutch 25 will be connected.

  Next, the operation of the turbocharger 62 and the control method of the lockup clutch 25 of the present invention when the vehicle starts will be described. When the vehicle is stopped, the turbine 22 of the fluid coupling 2 connected to the wheels does not rotate. Since the lock-up clutch 25 is disengaged and the pump 21 can rotate independently, when the diesel engine 61 is started, the pump 21 starts rotating at the engine idling speed. The speed ratio is zero (see FIG. 7). When the driver releases the brake and depresses the accelerator pedal from this state, the engine speed rapidly increases, the turbine 22 speed gradually increases, and the vehicle starts to start. The speed ratio also increases gradually, and the sliding of the fluid coupling 2 decreases accordingly.

  Since the turbocharger 62 mounted on the diesel engine 61 is driven by the exhaust gas of the engine, the turbocharger 62 does not exhibit a sufficient function until the amount of exhaust gas is small and the energy is not increased. In addition, since there is an operation delay based on the inertia of the compressor 621 and the compressor drive turbine 622, as described above, even if the engine is started, the output of the diesel engine 61 is suppressed for a certain period, and the engine speed is reduced. Reaches a peak near the stall rotation speed of the first stage. However, even during this period, the rotational speed of the turbine 22 of the fluid coupling 2 gradually increases and the speed ratio increases, and the vehicle speed of the vehicle also increases accordingly. When the first stage stall rotation speed is reached, the speed ratio exceeds 0.5.

The operating state in which the rotational speed of the turbocharger 62 is low and sufficient performance is not exhibited is for a short period of time, after which the output torque and rotational speed of the diesel engine 61 increase. Since the driver has depressed the accelerator pedal greatly at the time of departure, the engine is almost in a full-load operation state after the operation delay period has elapsed. In the present invention, before the diesel engine enters such a high output state, that is, when the speed ratio in the fluid coupling rises to a predetermined speed ratio (0.7 or less) corresponding to the first stage stall speed. The lockup clutch control device 70 is set so as to generate a command signal for engaging the lockup clutch 25.

  In order to carry out such control, here, the rotational speed sensor 71 for detecting the rotational speed of the diesel engine 61 (the rotational speed of the pump 21) and the rotational speed of the turbine 22 (the input shaft of the wet multi-plate clutch 3). A rotation speed sensor 72 (FIG. 1) for detecting the rotation speed) is used. When the vehicle starts, the speed ratio in the fluid coupling is calculated from the signals of these rotational speed sensors, and when the speed ratio reaches a predetermined speed ratio of 0.7 or less, connection of the lockup clutch 25 is commanded, The flow path switching valve 52 is switched. The hydraulic oil flows from the working chamber between the pump and the turbine to the front chamber 28 through the chamber 29 behind the clutch disc 26, and the friction fading 27 of the clutch disc 26 is pressed against the inner surface of the casing 23. At this time, the lock-up clutch control device 70 adjusts the switching speed of the flow path switching valve 52 by changing the duty ratio of the control pulse, and appropriately controls the hydraulic pressure that presses the clutch disk 26 to achieve a smooth connection. Let it be done.

  The predetermined speed ratio at which the engagement command signal is output is set as a speed ratio at the time when the engine speed reaches a peak near the first stage stall speed. This time is a time when the engine speed, that is, the change in the speed of the pump 21 is small, and the lockup clutch 25 can be stably connected, and the time required for fastening is shortened. Fastening shock can be avoided.

  Thereafter, as the output of the turbocharger 62 increases, the rotational speed of the diesel engine 61 inevitably increases again. At this time, the engagement of the lockup clutch 25 is completed and the crankshaft 1 is moved to the transmission 4. It is in a directly connected state. A vehicle that has been in a low-speed running state after starting is smoothly accelerated when the output torque and the rotational speed of the diesel engine 61 are increased, and the vehicle speed does not fluctuate as shown in FIG.

In the present invention, the lockup clutch 25 is engaged at a time when the speed ratio is a predetermined speed ratio (0.7 or less) corresponding to the first stage stall rotation speed. As compared with the above, the difference in rotational speed between the pump 21 and the turbine 22 at the time of fastening is large. However, hydraulic fluid of the fluid coupling always flows around the friction fading 27 of the lockup clutch 25, and the engagement shock hardly occurs even in the case of the engagement in the case where the rotational speed difference is large due to the buffer action. . If necessary, means for increasing the hydraulic pressure of the trochoid pump 51 or increasing the pressure drop at the front and rear surfaces of the clutch disk 26 can be employed to increase the operating force for engaging the lockup clutch 25. .

For smooth engagement of the lock-up clutch 25, it is desirable that the difference between the rotational speed of the pump 21 and the rotational speed of the turbine 22 is small at the time of engagement, but when the output torque of the diesel engine 61 increases, it is engaged. It is desirable that is completed. Considering these points, in this embodiment of the present invention, the predetermined speed ratio at which the fastening command signal is output is set to 0.55 . Generally, it is preferable to set in the range of 0.5 to 0.6 which is the speed ratio at which the first stage stall occurs. Further, when the combination of the engine and the fluid coupling is determined and the speed ratio is determined corresponding to the engine speed, the lockup clutch 25 is engaged when the engine speed corresponding to the predetermined speed ratio is reached. It is possible to output this command.

  FIG. 6 shows a flowchart of lockup clutch engagement control according to the present invention. When the diesel engine 61 is started and the vehicle starts to start, the vehicle speed is detected (S1), and it is determined whether or not the vehicle speed exceeds, for example, 10 km / h (S3). This is because when the vehicle speed is too low, the vehicle travels unstable and is not suitable for fastening the lockup clutch 25. When the vehicle speed does not reach a certain value, the flow is terminated without outputting a lockup clutch command. In addition, regarding the speed ratio of the fluid coupling described below, the vehicle speed determination condition can be omitted in a power transmission device in which the vehicle speed always exceeds a certain value when this becomes a predetermined speed ratio.

  When the vehicle speed exceeds a certain value, it is determined whether or not the speed ratio of the fluid coupling 2 has reached a predetermined value of 0.55 (S4). For this reason, the rotational speed sensor 71 of the engine and the rotational speed sensor 72 of the turbine 22 always detect the rotational speeds of both, and the calculation of the speed ratio is executed (S2). When the speed ratio is less than or equal to the predetermined speed ratio, the flow is terminated because it is not yet the time to engage the lockup clutch. When the predetermined value is reached, it is determined that the proper timing has been reached, and the lockup clutch control device 70 outputs a command for engaging the lockup clutch 25 and starts duty ratio control for engagement (S5, S6). If the speed of the transmission 4 is determined to be the first speed, for example, the starting speed, the vehicle speed and the rotational speed of the turbine 22 are in a one-to-one relationship, so the vehicle speed is set instead of the rotational speed of the turbine 22. It may be used. Further, when the speed ratio is determined corresponding to the engine speed, the determination in step 4 can be made based only on the engine speed.

  As described in detail above, the present invention provides a vehicle power transmission device that combines a turbo engine and a fluid coupling with a lock-up clutch, and includes means for detecting the operating state of the turbocharger, while monitoring the operating state. The timing of lock-up clutch engagement after the start is optimized. Therefore, it is apparent that the present invention can be applied not only to a diesel engine but also to a gasoline engine that performs turbocharging, and to a power transmission device that does not interpose a clutch such as a wet multi-plate clutch behind a fluid coupling. .

It is the schematic of the power transmission device for vehicles with a fluid coupling to which the lockup clutch control apparatus of this invention is applied. It is sectional drawing of the fluid coupling etc. in the power transmission device for vehicles. It is sectional drawing of the partition part of the power transmission device for vehicles. It is a figure which shows the operating characteristic when combining an engine and a fluid coupling. It is a figure which shows the operating characteristic with time of the engine provided with the turbocharger. It is a flowchart which shows the action | operation of the lockup clutch control apparatus of this invention. It is a figure which shows operation | movement at the time of start etc. of the vehicle provided with the lockup clutch control apparatus of this invention. It is a figure which shows the action | operation at the time of start etc. of the vehicle carrying a naturally aspirated type engine. It is a figure which shows operation | movement at the time of start etc. of the vehicle carrying a turbocharger engine and provided with the conventional lockup clutch control apparatus.

Explanation of symbols

1 Crankshaft 2 Fluid coupling (fluid coupling)
21 Pump 22 Turbine 25 Lock-up clutch 26 Clutch disc 3 Wet multi-plate clutch 4 Transmission 61 Diesel engine 62 Turbocharger 70 Lock-up clutch control device 71 Engine speed sensor 72 Turbine speed sensor

Claims (5)

A vehicle power transmission device in which a fluid coupling (2) is connected to an engine (61) equipped with a turbocharger (62) ,
The fluid coupling (2) includes a pump (21) coupled to the crankshaft (1) of the engine (61), a turbine (22) coupled to the output shaft of the fluid coupling (2), and the pump. (21) and a lockup clutch (25) for fastening the turbine (22), and a lockup clutch control device (70) for fastening the lockup clutch (25), and
When the vehicle starts, the vehicle power transmission device starts while sliding the pump (21) and the turbine (22) by disengaging the lock-up clutch (25) and rotating the engine (61). After the engine torque reaches the first stall rotational speed at which the output torque of the engine (61) balances with the load torque of the pump (21), the number increases again as the output of the turbocharger (62) increases. And then
The lockup clutch control device (70) detects a speed ratio that is a ratio of the turbine (22) rotation speed to the pump (21) rotation speed , and the speed ratio corresponds to the stall rotation speed of the first stage. The vehicle power transmission device is set so as to start the engagement of the lockup clutch (25) when the speed ratio is increased to a predetermined speed ratio . The lockup clutch (25) includes a clutch disk (26) disposed in the casing (23) of the fluid coupling (2) and connected to the turbine (22). 2), the clutch disc (26) is pressed against the casing (23) by the pressure of the hydraulic oil in the casing (23) of the fluid coupling (2). apparatus. The lockup clutch control device (70) calculates the speed ratio based on detection values of the engine speed sensor (71) and the turbine speed sensor (72), and when the speed ratio increases to the predetermined speed ratio , The vehicle power transmission device according to claim 1 or 2, wherein the vehicle power transmission device is set to output a command to engage the up clutch (25). When the engine speed detected by the engine speed sensor (71) rises to a speed corresponding to the predetermined speed ratio, the lockup clutch control device (70) The vehicle power transmission device according to claim 1, wherein the vehicle power transmission device is set to output a fastening command. The said engine (61) is a diesel engine, The control apparatus of the vehicle power transmission device in any one of Claims 1 thru | or 4.

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