JPH0260898B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power transmission device for a vehicle.

A belt type continuously variable transmission is well known as a power transmission device for a vehicle internal combustion engine, and the power transmission efficiency of this continuously variable transmission is approximately constant under all conditions in a conventional gear type stepped transmission ( It is generally known that it varies greatly depending on the gear ratio, input shaft rotation speed, and input shaft torque, and becomes higher in the low rotation speed and high torque range. There is. Furthermore, compared to a stepped transmission, a continuously variable transmission can set an arbitrary shift range and select variable speed within that range, so it is theoretically superior in fuel economy and acceleration performance.

In particular, with regard to fuel economy, in conventional stepped transmissions, the gear ratio is determined primarily, so the fuel efficiency characteristics of the engine are inevitably determined for a given output of the internal combustion engine, but with continuously variable transmissions, By appropriately selecting a high gear ratio, the internal combustion engine can be operated in a low rotational speed and high torque range for the above-mentioned predetermined output, and therefore minimum fuel consumption characteristics can be obtained.

However, in a piston-type internal combustion engine, torque fluctuations occur due to inertia associated with reciprocating piston motion and torque fluctuations occur due to pressure fluctuations in the combustion chamber, and the crankshaft thereof rotates with torque fluctuations and rotational speed fluctuations. This torque fluctuation impedes the drivability of vehicles equipped with internal combustion engines, and especially when driving at low speeds, torque fluctuations are transmitted to the vehicle, drive shaft, etc., and the average drive torque is not sufficient to drive the vehicle. However, due to vibrations caused by torque fluctuations, the low-speed limit operating speed actually increases. For this reason, when the above-mentioned continuously variable transmission is used, it is necessary to select a substantially large gear ratio, which results in an increase in the rotation of the internal combustion engine, resulting in a problem of worsening fuel efficiency.

Furthermore, belt-type continuously variable transmissions have problems with their durability because the belt slips when the vehicle is started and prematurely wears and damages the belt.

The present invention has been made to solve the above-mentioned problems, and includes an input shaft to which a prime mover that generates rotational power with torque fluctuations is connected, an output shaft, and a clutch device disposed between the two shafts. and a belt-type continuously variable transmission connected to the output shaft and capable of continuously changing speed by changing the pulley ratio, the input shaft rotational speed due to torque fluctuation of the input shaft. A slip rotation speed to be set based on the amount of variation in is determined, and the torque transmission capacity of the clutch device is adjusted so that the output shaft is rotated at a rotation speed lower by the slip rotation speed than the input shaft rotation speed. The gist of the present invention is a power transmission device for a vehicle characterized by being provided with a control means.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, a reciprocating piston type internal combustion engine 2
has a crankshaft 4, which is connected to a power transmission device 6. The power transmission device 6 consists of an electromagnetic clutch 8 and a belt type continuously variable transmission 10.

The electromagnetic clutch 8 includes a drive member 12 fixed to the crankshaft 4 forming a clutch input shaft, a clutch coil 14 provided on the drive member, and a clutch output shaft 16 fitted externally to the crankshaft 4. A gap 20 between the clutch coil 14 and the driven member 18 is filled with magnetic powder.

The continuously variable transmission 10 includes a drive pulley 22 provided on a clutch output shaft 16 forming a variable machine input shaft, a drive pulley 22 provided on an intermediate shaft 24, and a steel block belt 2 provided on an intermediate shaft 24.
A driven pulley 28 is rotatably driven by the drive pulley 22 via a drive pulley 28, a main drive gear 30 is fitted onto the intermediate shaft 24, a main reverse gear 32 is fitted onto the intermediate shaft 24, and a driven pulley 28 is spline-fitted to the intermediate shaft 24. , a shift sleeve 34 that is slid in the axial direction by a shift fork (not shown) and selectively meshes with the drive gear 30 or reverse gear 32 via a suitable clutch gear, and a variable machine output shaft 36.
A counter drive gear 38 that is fixed to the output shaft 36 and meshes with the drive gear 30, a counter reverse gear 42 that is fixed to the output shaft 36 and meshes with the reverse gear 32 via the reverse idle gear 40, and a counter reverse gear 42 that is fixed to the output shaft 36 and meshes with the differential gear 44. It has a final gear 46 that meshes with it. The drive pulley 22 consists of a pulley piece 48 fixed to the output shaft 16 and a pulley piece 50 spline-fitted to the output shaft. can be slid to change the effective radius of the drive pulley. Similarly, the driven pulley 28 is a pulley piece 5 fixed to the intermediate shaft 24.
4 and a pulley piece 56 spline-fitted to the intermediate shaft, and the pulley piece 56 is slid in the axial direction by a second hydraulically operated servo device 58 to change the effective radius of the driven pulley. Can be done.
The second servo device 58 has a spring 60 that biases the pulley piece 56 towards the pulley piece 54, which spring 60 is biased toward the pulley piece 54 due to the drive torque transmitted by the drive pulley 22 via the belt 26. It serves to supplement the hydraulic pressure acting on the driven pulley section to prevent section 56 from being moved in a direction that would reduce the effective radius of the driven pulley.

The first and second servo devices 52 and 58 are supplied with hydraulic pressure from an oil pump 62 driven by the crankshaft 4, and the hydraulic control device 64 is inversely proportional to the increase or decrease in the hydraulic pressure in the first servo device 52. The supply and discharge of hydraulic pressure is controlled to increase or decrease the hydraulic pressure within the second servo device 58.

A drive torque from the crankshaft 4 of the internal combustion engine 2 is transmitted to the output shaft 16 via an electromagnetic clutch 8 whose operation is controlled in a manner described later, thereby rotationally driving the drive pulley 22. The hydraulic control device 64 is operated according to a command from an electronic control device (not shown) depending on the operating state of the internal combustion engine, and controls the first and second servo devices 52.
The supply and discharge of hydraulic pressure to and 58 is controlled, and the effective radii of the drive pulley 22 and driven pulley 28 are inversely increased or decreased to select a predetermined gear ratio. The drive pulley 22 rotates the driven pulley 28 at a selected speed ratio via the belt 26, and the shift sleeve 3
The drive gears 30 and 38 or the reverse gears 32, 40 and 42 are driven depending on the selected drive position or reverse position of the final gear 4.
6 and a differential gear 44 to transmit driving torque to the wheels.

Next, an electronic control device for controlling the operation of the electromagnetic clutch 8 will be explained with reference to FIGS. 2 to 5.

As schematically shown in FIG.
6 responds to signals from a rotational speed detection device 68 that detects the rotational speed of the crankshaft 4, a rotational speed detection device 70 that detects the rotational speed of the clutch output shaft 16, and a depression amount detection device 74 of the accelerator pedal 72, respectively. Clutch coil 1 of electromagnetic clutch 8
The current of the power source 76 is supplied to and controlled by the power source 76.

The electromagnetic clutch 8 attracts magnetic particles into the gap 20 between the clutch coil 14 and the driven member 18 when current is supplied to the clutch coil 14, and the driven member is moved by friction through the magnetic particles and by the electromagnetic force of the clutch coil 14. The excitation current supplied to the clutch coil 14 and the transmission torque transmitted to the driven member 18 have characteristics shown in FIG. In other words, as the current increases, the transmitted torque gradually increases, and once the predetermined maximum excitation current A _O is reached, the transmitted torque also reaches the maximum value T _O , and after that, the transmitted torque almost increases even as the current increases. do not. Furthermore, when a predetermined current A _t is supplied, the transmitted torque does not exceed the transmitted torque value T _t corresponding to this current A _t , even if the driving torque of the clutch coil 14 , that is, the crankshaft 4 becomes large. The torque transmitted to the driven member 18, that is, the output shaft 16 is a value
_Tt is not exceeded, and the crankshaft 4 slips with respect to the output shaft 16.

In this embodiment, electronic controller 66 controls the current supplied to coil 14 of the electromagnetic clutch as follows.

In the circuit of the electronic control device 66 shown in FIG. 4, a circuit 78 calculates the fluctuation rotation speed ±ΔNe per unit time caused by torque fluctuation from the rotation speed Ne of the crankshaft 4 detected by the rotation speed detection device 68. The circuit 80 sets a set slip rotation speed Ns that is larger than the fluctuating rotation speed.

Also, the rotation speed Ne of the crankshaft detected by the rotation speed detection device 68 and the rotation speed of the output value 16 detected by the rotation speed detection device 70.
A circuit 82 detects the absolute value |Ne-Nt| of the rotational speed difference between Nt and Nt, and a circuit 84 smoothes this absolute value to detect a smoothed value No.

Circuit 86 is the set slip rotation speed from circuit 80.
Compare Ns with the smoothed value No. from the circuit 84, and
>Ns, the current supplied to the clutch coil 14 by the current supply circuit 88 is increased and the smoothed value is
If No<Ns, the current supplied to the clutch coil 14 by the current supply circuit 88 is reduced and the smoothing value No is increased.

Further, the circuit 80 is supplied with a signal corresponding to the amount of depression of the accelerator pedal 72 detected by the amount of depression detection device 74, and increases the set slip rotation speed Ns as the amount of depression of the accelerator pedal increases. to correct.

Furthermore, the current supply circuit 88 is connected to the rotational speed of the crankshaft detected by the rotational speed detection device 68.
It operates to supply the maximum current to the clutch coil 14 at a predetermined rotational speed or higher, for example 2000 rpm or higher.

Each circuit of the electronic control device 66 has a time difference because it exchanges or calculates signals from each detection device, and there is a response delay. Therefore, especially during deceleration, torque fluctuations may be transmitted through the electromagnetic clutch 8 due to a delay in the change in current supplied to the clutch coil due to this response delay. For this reason, a circuit 90 is provided to detect a change in the accelerator pedal depression amount signal detected by the depression amount detection device 74, and to correct the response delay when the accelerator pedal 72 is returned from the depressed state. A signal is supplied to the current supply circuit 88 to halve or stop the current supply to the clutch coil 14 for a predetermined period of time.

In this way, the electronic control unit 66 has a smoothed value.
The current supplied to the clutch coil 14 of the electromagnetic clutch 8 is feedback-controlled so as to match the slip rotation speed Ns, and as shown in FIG. The output shaft 16 is rotated at a rotation speed Nt that is lower than the speed Ne by a set slip rotation speed Ns that is larger than the fluctuation rotation speed ±ΔNe due to torque fluctuation. In addition, when the amount of accelerator pedal depression that increases torque fluctuation is large, the set slip rotation speed
By increasing Ns, an appropriate slip rotation speed can be set over a wide driving range, and when the amount of accelerator pedal depression is small, the slip rotation speed is reduced to improve responsiveness. Further, when the crankshaft rotational speed Ne is, for example, 2000 rpm or more, the maximum current is supplied to the clutch coil 14 of the electromagnetic clutch 8 to directly operate the electromagnetic clutch to improve responsiveness.

According to the power transmission device with the above configuration according to the present invention, the driving torque of the crankshaft rotating with torque fluctuation is transmitted to the output shaft 16 via the electromagnetic clutch 8, and the set slippage is lower than the rotational speed Ne of the crankshaft. Since the excitation current supplied to the electromagnetic clutch 8 is feedback-controlled so as to rotate the output shaft at a rotational speed Nt lower by the rotational speed Ns, the output shaft 16 is supplied with torque due to the torque fluctuation of the crankshaft 4 and the same torque fluctuation. No vibrations are transmitted, only a predetermined smooth torque is transmitted, so that a particularly low low limit operating speed is possible.

As a result, it becomes possible to use extremely effectively the low rotational speed and high torque range of the internal combustion engine in which the high power transmission efficiency of the continuously variable transmission can be obtained, and fuel efficiency can be effectively improved.

Further, since a predetermined slippage occurs in the electromagnetic clutch 8 at the time of starting, the vehicle can be started smoothly, and the belt 26 can be prevented from slipping with respect to the driven pulley 28 that may occur at the time of starting in the continuously variable machine 10. Therefore, the life of the belt can be extended and the durability of the continuously variable transmission can be improved.

Furthermore, in the above embodiment, since the continuously variable transmission is of a type that performs electro-hydraulic control of the pulley ratio, the electronic control device that controls the hydraulic control device 64 of the transmission and the clutch coil 14 of the electromagnetic clutch are controlled. It is possible to use the electronic control device 66 as a single common electronic control device, which is advantageous in terms of manufacturing cost.

Further, in the above embodiment, the electromagnetic clutch 8 is used as a crank device disposed between the crankshaft 4 and the output shaft 16 forming the input shaft of the continuously variable transmission 10. Even if a hydraulically operated friction clutch is used, the same effect as in the above embodiment can be obtained. In this case, as in the above embodiment, an appropriate electronic control device detects the rotational speed difference between the crankshaft and the crank output shaft at least in a range below a predetermined crankshaft rotational speed, and converts this difference into a set slip rotation. Feedback control of hydraulic pressure supply to the friction clutch to match speed. Also, in this case, it is possible to control the continuously variable transmission and the friction clutch through a common electronic control device, and the hydraulic pressure from the oil pump 62 of the transmission is used as the hydraulic pressure for the friction clutch. can be used.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of a power transmission device for a vehicle according to the present invention, Fig. 2 is a schematic explanatory diagram showing the electromagnetic clutch of Fig. 1 and its electronic control device, and Fig. 3 is an excitation current supplied to the electromagnetic clutch. and transmission torque characteristic diagram, Figure 4 is a block diagram of the electronic control unit,
FIG. 5 is a diagram showing the relationship between the rotational speeds of the crankshaft and the output shaft. 2... Internal combustion engine, 4... Crankshaft, 6... Power transmission device, 8... Electromagnetic clutch, 10... Continuously variable transmission, 12... Drive member, 14... Clutch coil, 16... Output shaft , 18... Driven member, 2
2... Drive pulley, 26... Belt, 28... Driven pulley, 52, 58... Servo device, 62...
Oil pump, 64...Hydraulic control device, 66...
Electronic control unit.

Claims (1)

[Claims] 1. An input shaft to which a prime mover that generates rotational power with torque fluctuation is connected, an output shaft, a clutch device disposed between both shafts, and a clutch device connected to the output shaft that changes the gear ratio by changing the pulley ratio. In a power transmission device equipped with a belt-type continuously variable transmission that can continuously change the output, the slip rotation speed is determined based on the amount of variation in the input shaft rotation speed due to the torque variation of the input shaft, and the output A power transmission device for a vehicle, comprising control means for adjusting the torque transmission capacity of the clutch device so that the shaft is rotated at a rotation speed lower than the input shaft rotation speed by the slip rotation speed.