Vehicle control device

Abstract

The invention provides a vehicle control device capable of suppressing generation of crankshaft shock. When it is determined that a crank shock is likely to occur on the basis of the travel history of the vehicle, the shift line from the first gear to the second gear in the shift map of the automatic transmission is changed to the lower vehicle speed side than in the normal time. Thus, when it is determined from the travel history of the vehicle that the friction coefficient of the sliding part is likely to increase, such as a high temperature of the sliding part or a short travel distance of the vehicle, and a crank shock occurs, the automatic transmission is advanced to a low vehicle speed side in the upshift of the second gear, and therefore, during the extension of the sliding part, the surface pressure of the sliding part is reduced, and the surface pressure of the sliding part is reduced. The occurrence of crankshaft shock can be suppressed.

Description

TECHNICAL FIELD

[0001] The present application relates to a control device of a vehicle provided with a propeller shaft having a sliding portion. BACKGROUND

[0002] A propeller shaft that transmits power from a power source of a vehicle to a drive wheel rotates at high speed, and needs to follow a change in vehicle posture that accompanies inertial force at the time of start and stop, and is provided with a sliding portion that can extend and contract in the axial direction. For example, the propeller shaft described in Patent Literature 1 is such a propeller shaft. In Patent Literature 1, a lubricating composition and a lubricating method are disclosed that suppress the generation of stick-slip due to a decrease in the sliding properties of the sliding portion over a long period of use, and reduce the impact (hereinafter, referred to as crankshaft impact) that is generated from the propeller shaft due to the generation of stick-slip.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2015-74659

[0006] In addition, the technology described in Patent Literature 1 has the effect of being able to maintain the sliding properties of the sliding portion of the propeller shaft over a long period of time, but there are issues in countermeasures for cases where the coefficient of friction of the sliding portion is larger than usual, such as in the case of high temperatures with respect to the sliding portion, at the initial operation when the sliding action of the sliding portion has not yet adapted, and in the case of a short vehicle travel distance (ODO). When the coefficient of friction becomes large, for example, in the case where the sliding portion is extended from a contracted state, in the case where the torque from the power source is transmitted to the propeller shaft, the frictional force that is generated based on the surface pressure (hereinafter, referred to as sliding portion surface pressure) of the sliding portion that is acted on by the transmitted torque from the power source with respect to the force (hereinafter, referred to as extension force) that wants to extend the sliding portion becomes large. Therefore, when the extension force is below the frictional force, the sliding portion does not slide but is fixed, and at the moment when the extension force becomes larger than the frictional force, the sliding of the sliding portion toward extension begins, and stick-slip in which the fixation is released is likely to occur, and the crankshaft impact is likely to occur. There are issues in the suppression of the generation of the crankshaft impact in the case where the coefficient of friction of the sliding portion becomes large and the crankshaft impact is likely to occur. SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The present application was completed with the above circumstances as a background, and aims to provide a control device of a vehicle that is able to suppress the generation of a crankshaft impact.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The gist of the first invention is to provide a control device of a vehicle (a) that is driven by a power source via a transmission shaft having a sliding portion that is able to expand and contract in the axial direction, from an automatic transmission to drive wheels, wherein (b) in a case where it is judged from a travel history of the vehicle that it is likely that a crankshaft shock will occur, a shift line of a shift map of the automatic transmission from 1st to 2nd is changed to the low vehicle speed side compared to normal times.

[0011] Inventive Effects

[0012] According to the first invention, the control device changes the shift line of the shift map of the automatic transmission from 1st to 2nd to the low vehicle speed side compared to normal times in a case where it is judged from the travel history of the vehicle that it is likely that a crankshaft shock will occur. Thereby, in a case where it is judged from the travel history of the vehicle that the temperature of the sliding portion is high or the coefficient of friction of the sliding portion is likely to become large due to a short odometer (ODO) and the like, and a crankshaft shock is likely to occur, by advancing the upshift of the automatic transmission to 2nd to the low vehicle speed side, the sliding portion face pressure is able to be reduced in the expansion of the sliding portion, and therefore, the occurrence of a crankshaft shock is able to be suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a diagram that explains the outline structure of the vehicle to which the invention is applied.

[0014] Figure 2 is a diagram that explains an example of the operation of the transmission shaft in relation to the occurrence of a crankshaft shock.

[0015] Figure 3 is a flowchart that explains the main part of the control operation of the electronic control device, and is a flowchart that explains the control operation for suppressing the occurrence of a crankshaft shock.

[0016] EXPLANATION OF REFERENCE NUMERALS

[0017] 10: vehicle, 12: engine (power source), 14: drive wheels, 20: power transmission device, 22: automatic transmission, 24: transmission shaft, 30: sliding portion, 50: electronic control device (control device). DETAILED DESCRIPTION

[0018] Hereinafter, an embodiment of the invention will be explained in detail with reference to the drawings.

[0019] EMBODIMENT

[0020] Figure 1 is a diagram that explains the outline structure of the vehicle 10 to which the invention is applied. Figure 1 (a) of is a diagram that explains the outline structure of the vehicle 10 as a whole. Figure 1Fig. 1 is a view showing an example of a power transmission device 20 provided in a vehicle 10. Fig. 2 is a view showing an example of a drive shaft 24 provided in the vehicle 10.

[0021] In Figure 1 In (a) of Fig. 1, the vehicle 10 is provided with an engine 12. In addition, the vehicle 10 is provided with a drive wheel 14 and a power transmission device 20 provided in a power transmission path between the engine 12 and the drive wheel 14. The engine 12 corresponds to the "power source" of the present application.

[0022] The engine 12 is a publicly known internal combustion engine, and the torque of the engine 12, i.e., the engine torque Te, is controlled by an electronic control device 50 described later.

[0023] The power transmission device 20 is provided with an automatic transmission 22, a drive shaft 24, a differential gear 26, and the like, and transmits power from the engine 12 to the drive wheel 14 from the automatic transmission 22 via the drive shaft 24 and the differential gear 26 and the like in this order.

[0024] In Figure 1 In (b) of Fig. 1, the upper left portion shows a cross-sectional view of the drive shaft 24, and the other portions are front views showing the outer shape. The power transmission device 20 is further provided with a first universal joint 28 and a second universal joint 29. The drive shaft 24 is coupled to an output shaft 22a of the automatic transmission 22 via the first universal joint 28, and is coupled to an input shaft 26a of the differential gear 26 via the second universal joint 29 (see (a) of Fig. 2). Figure 1

[0025] The drive shaft 24 has a sliding portion 30 that is capable of extending and contracting in the axial direction, i.e., the axial direction of the drive shaft 24. The sliding portion 30 is a sliding mechanism for following a change in length between the automatic transmission 22 and the differential gear 26 caused by, for example, a change in vehicle posture at the time of acceleration or deceleration.

[0026] The sliding portion 30 is provided with a first hollow shaft 32, a second hollow shaft 34, and a cover member 36. The first hollow shaft 32 is engaged with the first universal joint 28. The second hollow shaft 34 is engaged with the second universal joint 29. The first hollow shaft 32 is formed with an outer spline 32a for spline fitting on a portion of an outer peripheral surface. The second hollow shaft 34 is formed with an inner spline 34a for spline fitting on a portion of an inner peripheral surface. The outer spline 32a of the first hollow shaft 32 and the inner spline 34a of the second hollow shaft 34 are spline-fitted so as to be incapable of relative rotation around the axial center CL and capable of relative movement in the axial center CL direction. The cover member 36 is a member for blocking the entry of foreign matter, for example, from the outside into the portion in which the first hollow shaft 32 and the second hollow shaft 34 are spline-fitted.

[0027] ​The vehicle 10 also includes an electronic control unit 50, which comprises the control devices for the vehicle 10. The electronic control unit 50 is configured to include a so-called microcomputer.

[0028] Various signals based on detection signals from various sensors (not shown) equipped on the vehicle 10 are supplied to the electronic control unit 50. These signals include, for example, engine speed Ne, transmission input speed Ni, transmission output speed No, vehicle acceleration G, external air temperature Ta, and accelerator opening θacc.

[0029] Engine speed Ne is the rotational speed of engine 12. Transmission input speed Ni is the input speed of automatic transmission 22. Transmission output speed No is the output speed of automatic transmission 22, and it corresponds to vehicle speed V. Furthermore, the vehicle travel distance ODO is accumulated based on vehicle speed V and travel time. Vehicle acceleration G is a signal representing the acceleration in vehicle 10. External air temperature Ta is the external air temperature of vehicle 10. Accelerator opening θacc is the amount of accelerator operation by the driver, representing the magnitude of the driver's acceleration operation.

[0030] Various command signals are output from the electronic control unit 50 to control the various devices (such as the engine 12, automatic transmission 22, etc.) of the vehicle 10. These command signals include, for example, the engine control command signal Se and the transmission control command signal Sat.

[0031] The electronic control unit 50 calculates the driver's driving demand on the vehicle 10 by applying the accelerator opening θacc and vehicle speed V to a drive demand mapping, for example, calculating the required drive torque Trdem in the drive wheels 14, and outputting various command signals to achieve the required drive torque Trdem. Furthermore, the electronic control unit 50 performs automatic transmission 22 shift determination by applying the required drive torque Trdem and vehicle speed V to a shift mapping, and executes shift control as needed. The shift mapping, for example, is a pre-defined relationship on a two-dimensional coordinate system where the required drive torque Trdem and vehicle speed V are set as variables, with shift lines for determining the shift of the automatic transmission 22.

[0032] Figure 2 This is a diagram illustrating an example of drive shaft movement related to the generation of crankshaft impact S. Figure 2 (a) is a timing diagram showing the progression of actions. Figure 2 (b) is in Figure 2 The timing diagram of (a) applies variable speed mapping during the action.

[0033] exist Figure 2In (a), the upper layer shows the vehicle behavior, the middle layer shows the face pressure (hereinafter, referred to as the sliding portion face pressure) PS of the torque transmitted from the engine 12 to the propeller shaft 24 acting on the sliding portion 30, and the lower layer shows the contraction amount, i.e., the sliding amount L of the sliding portion 30. In addition, regarding the behavior after the time tla described later with respect to the sliding portion face pressure PS and the behavior after the time t2 described later with respect to the sliding amount L, the broken line shows the behavior in the case where the present application is not applied (hereinafter, referred to as the conventional example), and the solid line shows the behavior in the case where the present application is applied (hereinafter, referred to as the embodiment).

[0034] In Figure 2 In (a), in the behavior of the conventional example (broken line), when the vehicle 10 starts and accelerates from the stopped state at the time tl, the sliding portion 30 of the propeller shaft 24 slides and contracts to the sliding amount L = LI due to the change in the vehicle posture accompanying the stroke of the rear suspension. During the acceleration, the sliding portion face pressure PS increases to PI. Thereafter, the vehicle 10 is decelerated by the accelerator being off at the time T2, the vehicle posture is restored, and the elongation force E, which is a force (hereinafter, referred to as the elongation force) for elongating the sliding portion 30, acts on the propeller shaft 24. In addition, the sliding portion face pressure PS decreases accompanying the deceleration, and the frictional force R generated based on the sliding portion face pressure PS also decreases. However, before the sliding portion face pressure PS decreases to P2, the elongation force E is lower than the frictional force R, and the sliding portion 30 is not sliding but fixed in the contracted state. Then, at the time t3 when the sliding portion face pressure PS decreases to P2 and the elongation force E becomes greater than the frictional force R, the sliding of the sliding portion 30 to the elongation is started, and stick-slip in which the fixing is released is generated. Due to the generation of the stick-slip, the crank shock S (refer to the oval encircled portion in the drawing) is generated from the propeller shaft 24. The "stick-slip" in the present specification corresponds to the following behavior: for the sliding portion 30 in the contracted state, when the elongation force E is lower than the frictional force R, the sliding portion 30 is not sliding but fixed in the contracted state, and at the time when the elongation force E becomes greater than the frictional force R, the sliding of the sliding portion 30 to the elongation is started and the fixing is released.

[0035] In the case where the frictional coefficient of the sliding portion 30 becomes greater than that at normal times, for example, in the case where the sliding portion 30 is at a high temperature, in the initial operation when the sliding behavior of the sliding portion 30 has not been adapted, i.e., in the case where the vehicle running distance ODO is short, and the like, the stick-slip (crank shock S) is easily generated. When the frictional coefficient of the sliding portion 30 becomes greater, the frictional force R also becomes greater, and thus the sliding portion face pressure PS, which causes the sliding portion 30 to be not sliding but fixed in the contracted state, becomes lower than that at normal times (= P2). In addition, the longer the decrease in the sliding portion face pressure PS to P2 becomes, the longer the period during which the sliding portion 30 is not sliding but fixed in the contracted state becomes, and thus the stick-slip, i.e., the crank shock S, is easily generated.

[0036] Therefore, when the electronic control device 50 determines that the friction coefficient of the sliding part 30 has increased and that crankshaft impact S may occur, it changes the shift line of the automatic transmission 22 from 1st to 2nd gear to the low speed side compared to normal operation. Figure 2 (b) shows the shift lines from 1st to 2nd gear in the shift mapping of the automatic transmission 22. The dashed line indicates the normal shift line, and the solid line indicates the shift line during gear changes. Additionally, in Figure 2 In the variable speed mapping of (b), the progression of each time point (t1, t1a, t2, t3) in the existing example and the embodiment is shown with white circles and single-dot dashed arrows, and the embodiment is shown with black circles and solid arrows. Figure 2 As shown in (a) and (b), in the conventional example, a normal gear shift line is used, and no upshifting occurs from time t1 to time t3; instead, the aforementioned operation is performed in first gear. On the other hand, in the embodiment, a modified gear shift line is used. Starting from the start at time t1, as the vehicle speed V accelerates, an upshift from first gear to second gear occurs at time t1a. By upshifting to second gear, the required drive torque Trdem decreases, and the torque transmitted to the drive shaft 24 also decreases. Therefore, the sliding surface pressure PS also decreases accordingly. When the accelerator is disengaged at time t2, the sliding surface pressure PS decreases below P2, and the elongation force E is greater than the frictional force R. Therefore, during the deceleration of the vehicle 10, the sliding part 30 begins to slide from a contracted state to an extended state. Thus, the generation of crankshaft impact S can be suppressed.

[0037] Figure 3 It is a flowchart illustrating the main part of the control operation of the electronic control device 50, and a flowchart illustrating the control operation for suppressing the generation of crankshaft impact S, which is repeatedly executed, for example.

[0038] exist Figure 3In the present embodiment, the steps of the flowchart correspond to functions of the electronic control device 50. In step (hereinafter, "step" is omitted) S10, it is determined from the travel history of the vehicle 10 whether the friction coefficient of the sliding portion 30 is likely to become large and the crankshaft shock S is likely to occur. As shown in the dialog of S10, this determination is made, for example, by a determination of whether (1) the temperature of the sliding portion 30 is high or (2) the vehicle travel distance ODO is equal to or less than a prescribed distance SL. Further, the determination of whether (1) the temperature of the sliding portion 30 is high is made, for example, by a determination of whether (a) the outside air temperature Ta is equal to or more than a prescribed temperature Tc and (b) the vehicle 10 is driven at a high load (the drive output W is equal to or more than a prescribed output Wh) for a prescribed period Th or more. As for the prescribed distance SL, a preferable value that can be determined from the temporal characteristics of the friction coefficient of the sliding portion as being large can be set by preliminary design or experiment. The drive output W is calculated, for example, by integrating the torque transmitted from the automatic transmission 22 to the drive shaft 24 and the transmission output speed No. Further, as for the prescribed temperature Tc, the prescribed output Wh, and the prescribed period Th, preferable values that can be determined as the temperature of the sliding portion 30 being high can be set respectively by preliminary design or experiment. In the case where the determination of S10 is affirmative, in S20, the shift line of the shift map of the automatic transmission 22 from 1st to 2nd is changed to the low vehicle speed side (of (b) the change), and the routine is ended. In the case where the determination of S10 is negative, in S30, the shift line of the shift map of the automatic transmission 22 from 1st to 2nd is returned to the normal setting (of (b) the normal), and the routine is ended. Figure 2 Figure 2

[0039] As described above, according to the present embodiment, in the case where it is determined from the travel history of the vehicle 10 that the crankshaft shock S is likely to occur, the shift line of the shift map of the automatic transmission 22 from 1st to 2nd is changed to the low vehicle speed side compared to the normal. Thereby, in the case where it is determined from the travel history of the vehicle 10 that the temperature of the sliding portion is high or the vehicle travel distance ODO is short, and so on, the friction coefficient of the sliding portion 30 is likely to become large and the crankshaft shock S is likely to occur, the upshift of the automatic transmission 22 to 2nd is advanced to the low vehicle speed side, and thus, in the elongation of the sliding portion 30, the sliding portion face pressure PS is reduced, and the occurrence of the crankshaft shock S can be suppressed.

[0040] The above-described embodiment of the present application has been described based on the drawings, but the present application can be applied to other modes.

[0041] ​​For example, in the above-described embodiment, the vehicle 10 is an engine vehicle that uses only the engine 12 as a power source, but the present application can be applied even to a hybrid vehicle (HEV) that uses both an engine and a motor as a power source, or an electric vehicle (BEV) that uses only a motor as a power source.

[0042] Furthermore, the above-described content is merely one embodiment, and the present application can be implemented in various forms to which various changes and modifications based on the knowledge of those skilled in the art are applied.

Claims

1. A control device of a vehicle that transmits power from an automatic power source to drive wheels via a propeller shaft having a sliding portion that is able to expand and contract in an axial direction, characterized in that, in a case where it is judged from a travel history of the vehicle that it is likely that a crankshaft impact will occur, a shift line of a shift map of the automatic transmission from 1st to 2nd is changed to a low vehicle speed side compared to a normal time.

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