JP2013137059A - Control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately suppress the speed of a creep run of a vehicle due to a creep phenomenon.SOLUTION: A control device is used for a vehicle in which driving force output from an engine is input to a transmission 8 via a torque converter 7 and is transmitted to an axle 103. The control device performs control so that a lock-up clutch 73 of the torque converter 7 is brought into a sliding friction state during a creep in which an accelerator pedal is not depressed. Thereby, a torque ratio of the torque converter 7 is decreased, torque transmitted to the axle 103, that is, a creep force is reduced and the speed of the creep run is decreased.

Description

  The present invention relates to vehicle control in a mode in which driving force output from an engine is input to a transmission via a torque converter and transmitted to an axle.

  Recently, for the purpose of further improving practical fuel consumption, reduction of mechanical loss in an internal combustion engine and a drive system, reduction in weight of a vehicle equipped with these, reduction in running resistance, and the like have been attempted. On the other hand, the output performance of the internal combustion engine and the torque converter has not changed or improved rather than before.

  As a result, the creep force due to the creep phenomenon (see, for example, the following patent document) is relatively increased, and the speed of creeping travel of the vehicle is increasing. If the creep speed is too high, the ease of use becomes worse when the road is congested or garaged.

As a means to suppress the creep speed,
(I) Decreasing the idling speed of the internal combustion engine (ii) Changing the design so as to reduce the torque capacity coefficient of the torque converter (iii) Increasing mechanical loss in each part of the vehicle (iv) Nearest low gear in the transmission It is conceivable to reduce the speed reduction ratio (maximum speed reduction ratio) of the first gear.

  (I) is ideal if it can be realized. However, the engine idling speed has already been kept close to the limit, and lowering the idling speed further can cause frequent engine stalls and is difficult.

  In (ii), when the vehicle starts, the output torque of the engine may not be transmitted directly to the transmission and the axle, and the engine speed increases and fuel consumption increases accordingly. In addition, the cost of new design and production of the torque converter is not negligible.

  (Iii) can be said to fall over at the end because the fuel efficiency is deteriorated in the first place.

  (IV) can reduce the creep force transmitted to the axle, but weakens acceleration performance and climbing performance at the time of restart.

JP 2007-331463 A

  An object of the present invention is to appropriately suppress the speed of creeping of a vehicle due to a creep phenomenon.

  In the present invention, the driving force output from the engine is input to the transmission via the torque converter and transmitted to the axle, and the torque converter lock-up clutch is slipped and frictioned during creep when the accelerator pedal is not depressed. A control device characterized by executing control to be in a state is configured.

  According to the present invention, it is possible to appropriately suppress the creeping speed of the vehicle due to the creep phenomenon.

The figure which shows the whole structure of the internal combustion engine for vehicles in one Embodiment of this invention. The figure which shows the structure of the drive system in the embodiment.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. This spark ignition type internal combustion engine is of a direct injection type, and includes a plurality of cylinders 1 (one of which is shown in FIG. 1) and an injector 10 for injecting fuel into each cylinder 1. An intake passage 3 for supplying intake air to each cylinder 1, an exhaust passage 4 for discharging exhaust from each cylinder 1, and an exhaust turbocharger 5 for supercharging intake air flowing through the intake passage 3; And an external EGR device 2 that recirculates EGR (Exhaust Gas Recirculation) gas from the exhaust passage 4 toward the intake passage 3.

  A spark plug 13 is attached to the ceiling of the combustion chamber of the cylinder 1. The spark plug 13 receives spark voltage generated by the ignition coil 12 and causes spark discharge between the center electrode and the ground electrode. The ignition coil 12 is integrally incorporated in a coil case together with an igniter 11 that is a semiconductor switching element.

  The intake passage 3 takes in air from the outside and guides it to the intake port of the cylinder 1. On the intake passage 3, an air cleaner 31, a compressor 51 of the supercharger 5, an intercooler 32, an electronic throttle valve 33, a surge tank 34, and an intake manifold 35 are arranged in this order from the upstream side.

  The exhaust passage 4 guides exhaust generated as a result of burning fuel in the cylinder 1 from the exhaust port of the cylinder 1 to the outside. An exhaust manifold 42, a drive turbine 52 for the supercharger 5, and a three-way catalyst 41 are disposed on the exhaust passage 4. In addition, an exhaust bypass passage 43 that bypasses the turbine 52 and a waste gate valve 44 that is a bypass valve that opens and closes the inlet of the bypass passage 43 are provided. The waste gate valve 44 is an electric waste gate valve that can be opened and closed by inputting a control signal l to the actuator, and a DC servo motor is used as the actuator.

  The exhaust turbocharger 5 is configured such that the drive turbine 52 and the compressor 51 are connected and linked in a coaxial manner. Then, the driving turbine 52 is rotationally driven by using the energy of the exhaust gas, and the compressor 51 is pumped by using the rotational force, whereby the intake air is pressurized and compressed (supercharged) and sent to the cylinder 1.

  The external EGR device 2 realizes a so-called high-pressure loop EGR. The inlet of the external EGR passage is connected to a predetermined location upstream of the turbine 52 in the exhaust passage 4. The outlet of the external EGR passage is connected to a predetermined location downstream of the throttle valve 33 in the intake passage 3, specifically to a surge tank 34. An EGR cooler 21 and an EGR valve 22 are also provided on the external EGR passage.

  FIG. 2 shows an example of a drive system provided in the vehicle. This drive system includes a torque converter 7 and an automatic transmission 8. The rotational torque output by the internal combustion engine is input from the crankshaft of the internal combustion engine to the pump impeller 71 on the input side of the torque converter 7 and transmitted to the turbine runner 72 on the output side. The rotation of the turbine runner 72 is transmitted to the input shaft of the automatic transmission 8 connected thereto, and the output shaft of the automatic transmission 8 is rotated through a shift (deceleration) by the automatic transmission 8. The rotation of the output shaft of the automatic transmission 8 is transmitted to the output gear 101. The output gear 101 meshes with the ring gear 102 of the differential device, and rotates the axle 103 and the drive wheel (not shown) via the differential device.

  The torque converter 7 includes a lockup mechanism. The lock-up mechanism is known in this field, and a lock-up clutch 73 that fastens the input shaft and output shaft of the torque converter 7 so as not to rotate relative to each other, and a hydraulic pressure for driving the lock-up clutch 73 to be connected and disconnected. And a lock-up solenoid valve (not shown) for controlling The lockup solenoid valve is a flow rate control valve that receives a control signal o and changes its opening.

  In general, the lockup mechanism fastens the input side and the output side of the torque converter 7 in a situation where the automatic transmission 8 does not change the speed ratio. During lockup, the lockup clutch 73 is pressed against the torque converter cover 74 and rotates together with the torque converter cover 74. During lockup, the engine torque input to the input side (drive plate) of the torque converter 7 is input from the torque converter cover 74 via the lockup clutch 73 to the output side of the torque converter 7 and to the input of the automatic transmission 8. Directly transmitted to the shaft. At the time of lockup, the speed ratio, which is the ratio of the output side rotational speed of the torque converter 7 to the input side rotational speed, is 1.

  In turn, the lock-up clutch 73 is separated from the torque converter cover 74 at the time of non-lock-up. When the engine is not locked up, the engine torque input to the input side of the torque converter 7 is transmitted from the torque converter cover 74 to the pump impeller 71 and the turbine 72, and is transmitted to the input shaft of the automatic transmission 8. At the time of non-lock-up, the speed ratio of the torque converter 7 becomes smaller than 1.

  The automatic transmission 8 is a stepped transmission using a planetary gear mechanism or the like, for example. The stepped automatic transmission 8 is also known in this field, and the stepped transmission 8 itself has a forward / reverse switching function, that is, the direction of rotation of the output shaft of the transmission 8 (forward rotation or reverse rotation), and thus the axle 103. A function to switch the rotation direction is attached. It is also conceivable to employ a continuously variable transmission such as a belt type CVT as the automatic transmission 8. In this case, a forward / reverse switching device is interposed between the torque converter 7 and the belt type CVT.

  An ECU (Electronic Control Unit) 0 that is a control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, an engine rotation signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. An accelerator opening signal c output from a sensor that detects the amount or the opening of the throttle valve 33 as an accelerator opening (in other words, a required load), a brake pedaling amount signal d output from a sensor that detects the amount of brake pedal depression Detecting intake air temperature / intake pressure signal e output from temperature / pressure sensor for detecting intake air temperature and intake pressure (or supercharging pressure) in intake passage 3 (especially surge tank 34) and engine coolant temperature The cooling water temperature signal f output from the water temperature sensor to be operated, the sensor for acquiring the shift lever range (or the shift position) Shift range signal g such that is output from the down switch) is input.

  From the output interface, an ignition signal i for the ignition plug igniter 11, an opening operation signal j for the EGR valve 22, an opening operation signal k for the throttle valve 33, and an opening for the waste gate valve 44. An operation signal l, a fuel injection signal m to the injector 10, an opening degree control signal o to the lockup solenoid valve of the lockup mechanism, a gear ratio control signal p to the automatic transmission 8, and the like are output.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, and g necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and fills the cylinder 1 with the intake air amount. Is estimated. Based on the engine speed and intake air amount, the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, EGR amount (or EGR rate) Then, various operating parameters such as ON / OFF of the compressor of the air conditioner, whether to lock up the torque converter 7 and the gear ratio of the automatic transmission 8 are determined. As the operation parameter determination method itself, a known method can be adopted. Therefore, the ECU 0 applies various control signals i, j, k, l, m, o, and p corresponding to the operation parameters via the output interface.

  The ECU 0 of the present embodiment has the shift position in the forward range or the reverse range, the accelerator pedal depression amount is 0 or less than a threshold value close to 0, and the internal combustion engine operates in an idling state or a state close thereto, During creep in which the output torque is transmitted to the axle 103 via the torque converter 7 and the automatic transmission 8, control is performed to bring the lock-up clutch 73 of the torque converter 7 into a sliding friction state.

When the torque capacity coefficient of the torque converter 7 is C, the input side rotational speed of the torque converter 7, that is, the engine rotational speed is Ne, and the torque ratio that is the ratio of the output side torque of the torque converter 7 to the input side torque is t. The torque T transmitted to the output side of
T = C ・ Ne ²・ t
It can be expressed as. During creep, the gear ratio of the automatic transmission 8 is controlled to be closest to the low gear (the reduction ratio is maximum). In order to reduce the creep force transmitted to the axle 103 via the automatic transmission 8 and reduce the creep travel speed of the vehicle, it is necessary to reduce any of the capacity C, the engine speed Ne or the torque ratio t in the above equation. There is. Decreasing the torque ratio t is synonymous with increasing the speed ratio.

  Therefore, the ECU 0 of the present embodiment dares to engage the lock-up clutch 73 during creep, and adjusts the opening of the lock-up solenoid valve to adjust the hydraulic pressure to press the lock-up clutch 73 against the torque converter cover 74. Adjustment is made to a sliding friction state in which the lock-up clutch 73 is slid with respect to the torque converter cover 74. As a result, the speed ratio of the torque converter 7 increases so as to approach 1, the torque ratio decreases, the transmission torque T decreases, and the creep force transmitted to the axle 103 decreases.

  The fastening strength of the lock-up clutch 73, that is, the strength of the hydraulic pressure that presses the lock-up clutch 73 against the torque converter cover 74 is controlled so that the vehicle speed during creep travel takes a desired value (or a desired range). It is preferable. The strength of the hydraulic pressure can be controlled by manipulating the opening of the lockup solenoid valve.

  For example, the ECU 0 measures the vehicle speed during creep travel, and performs feedback control to manipulate the opening of the lockup solenoid valve in a direction to reduce the deviation between the actual vehicle speed and a desired target vehicle speed. When the actual vehicle speed exceeds the target vehicle speed, the lockup clutch 73 is tightened to increase the speed ratio of the torque converter 7 and decrease the torque ratio. Conversely, when the actual vehicle speed is lower than the target vehicle speed, the lockup clutch 73 is loosened to lower the speed ratio of the torque converter 7 and increase the torque ratio.

  In this embodiment, the driving force output from the engine is input to the transmission 8 via the torque converter 7 and transmitted to the axle 103, and the torque converter 7 is locked during creep when the accelerator pedal is not depressed. The control device 0 is characterized in that it performs control to bring the up clutch 73 into a sliding friction state.

  According to the present embodiment, it is possible to appropriately suppress the speed of creeping of the vehicle due to the creep phenomenon. Further, since the creep force can be moderately suppressed even when the vehicle is stopped, the brake pedaling force can be reduced and the usability is improved.

  Compared with the above-mentioned methods (ii) and (iii), it is advantageous in that the practical fuel consumption does not deteriorate. In addition, it is not necessary to modify the hardware such as the internal combustion engine, the torque converter 7, and the transmission 8, and can be realized at low cost.

  When the accelerator pedal is depressed from the creep travel and re-accelerated, the lock-up clutch 73 is loosened and released so that a large torque shock does not occur.

  The present invention is not limited to the embodiment described in detail above. Various modifications can be made to the specific configuration of each part, processing procedure, and the like without departing from the spirit of the present invention.

  The present invention can be used for controlling a torque converter of a drive system mounted on a vehicle.

0 ... Control unit (ECU)
7 ... Torque converter 73 ... Lock-up clutch 8 ... Automatic transmission 103 ... Axle

Claims (1)

The driving force output from the engine is input to the transmission via the torque converter and transmitted to the axle.
A control device that performs control to bring a lock-up clutch of a torque converter into a sliding friction state during creep when the accelerator pedal is not depressed.

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