JP2008075688A - Power transmission device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress lowering of acceleration caused in gear shifting or the like without contributing to rotation fluctuation in low-speed rotation. <P>SOLUTION: A planet gear unit 21 is provided on an output side of an engine 11, and either of a ring gear 211, a pinion gear 212, and a sun gear 213 is connected to an input shaft of the unit 21, and any one of other gears is connected to an output shaft. The planet gear unit 21 includes a clutch 215 structured so as to connect at least two of the three gears 211-213 for forming the planet gear, and a brake 214 for restricting rotation of a third gear except for the two gears connected to the input shaft and the output shaft, and a rotating mass 216 for generating predetermined inertia moment is coupled to the third gear. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power transmission device for a vehicle, and more particularly, to suppress a reduction in acceleration caused by an inertial resistance acting on an engine at the time of shifting without impairing stability of low-speed rotation at the time of idling or the like. Related to technology.

As a power transmission device mounted on a vehicle, the following devices employing an automatic transmission are known.
That is, an internal combustion engine is provided as a drive source, and the crankshaft of this engine is connected to an automatic transmission via a torque converter. The driving force generated by the engine is transmitted to the drive wheels at a predetermined gear ratio by this automatic transmission. A forward clutch configured as a multi-plate clutch is interposed between the torque converter and the automatic transmission. The forward clutch connects and disconnects the output shaft of the torque converter and the input shaft of the automatic transmission. As an automatic transmission, a continuously variable transmission such as a belt drive type is known in addition to various multistage automatic transmissions represented by a planetary gear type. In such a power transmission device, the driving force generated by the engine is transmitted to driving wheels via a torque converter, a forward clutch, an automatic transmission, a final gear, a drive shaft, and the like to propel the vehicle (Patent Document 1). ).
JP 2004-003425 A (paragraph number 0011)

  Incidentally, the torque converter incorporates a direct coupling clutch generally called a lock-up clutch. In order to avoid transmission loss due to the slip of the torque converter, the crankshaft and the input shaft of the automatic transmission are directly connected by fastening this lock-up clutch during high-speed cruising with relatively small engine fluctuations. Thus, slippage of the torque converter is eliminated and transmission efficiency is improved.

  However, when shifting from the state in which the lock-up clutch is engaged, if the shift by the automatic transmission (ie, downshift) is made while maintaining this engagement state, the crankshaft, torque converter and forward clutch rotate together. Therefore, since the inertial resistance acting on the engine is large, the engine rotation cannot be increased rapidly, and the vehicle temporarily decelerates (hereinafter, this phenomenon is referred to as “shrink”). This causes a problem that drivability is impaired. On the other hand, if the weight of a rotating element such as a crankshaft is reduced and the inertial resistance is reduced, the increase in engine rotation itself becomes smooth. However, the weight reduction is naturally limited, and in this case, there is another problem that the low-speed rotation at the time of idling or the like becomes unstable.

  The present invention has been made in consideration of the above-described problems, and provides a power transmission device for a vehicle that can suppress a reduction in acceleration that occurs during a shift or the like without promoting rotational fluctuations during low-speed rotation. For the purpose.

  The power transmission apparatus for a vehicle according to the present invention uses an engine as a drive source, and is disposed on the output side of the engine. The input shaft is connected to the crankshaft of the engine and the output shaft is connected to the drive wheels of the vehicle. Equipped with a planetary gear unit. This planetary gear unit has a ring gear, a pinion gear, and a sun gear, and the input shaft is connected to one of these gears, and the output shaft is other than the one to which the input shaft is connected. Connected to one of the gears. The planetary gear unit is connected to a housing, a clutch configured to be able to connect at least two of three gears, a ring gear, a pinion gear, and a sun gear, and an input shaft or an output shaft of these gears. And a brake for restricting rotation of the third gear excluding the two gears with respect to the housing, and a rotating mass body coupled to the third gear for generating a predetermined moment of inertia.

  According to the present invention, the ring gear, the pinion gear, and the sun gear are rotated together by fastening the clutch of the planetary gear unit under the condition that the transmission efficiency of the driving force is required, and the driving wheel is driven by the planetary gear unit. The transmission loss can be eliminated and the driving force can be transmitted efficiently. On the other hand, when downshifting is performed in response to accelerator operation or the like, by releasing the clutch, the inertial resistance to the engine can be reduced, and a smooth increase in engine rotation can be ensured. Further, by providing the third mass other than the gear to which the input shaft or the output shaft is connected with the rotating mass body, the inertial energy held by the rotating mass body at the time of shifting is used to act on the engine. The inertial resistance to be offset can be offset, the engine speed can be increased more quickly, and the acceleration can be prevented from being lost during shifting. Note that, by engaging the clutch, the inertial mass of the entire rotating element including the rotating mass body is ensured, so that it is also possible to avoid the rotational fluctuation during the low-speed rotation.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a configuration of a vehicle power transmission device 1 according to an embodiment of the present invention. In the present embodiment, the power transmission device 1 includes a continuously variable transmission as an automatic transmission, and the continuously variable transmission includes a forward clutch for idle neutral control. In this embodiment, a belt drive type is adopted as the continuously variable transmission, but a toroidal type may be adopted, and various stepped automatics such as a planetary gear type may be used instead of the continuously variable transmission. It is also possible to employ a transmission.

  In the power transmission device 1 according to the present embodiment, a crankshaft of an internal combustion engine (hereinafter simply referred to as “engine”) 11 as a drive source is connected to an automatic transmission 41 via a torque converter 31 as a starting element. Configured. The automatic transmission 41 is provided with a forward clutch 411 configured as a multi-plate clutch. The forward clutch 411 is provided as means for switching between the neutral and drive ranges, whereby the output shaft of the torque converter 31 and the input shaft of the automatic transmission 41 (here, the next input pulley 412). The rotation axis). With the forward clutch 411 released, the transmission of the driving force from the engine 11 to the automatic transmission 41 is interrupted, and the automatic transmission 41 is set to the neutral range. Further, the automatic transmission 41 is provided with an input side pulley 412 and an output side pulley 413, and a metal belt 414 wound between these pulleys 412 and 413, and pulleys on the input side and the output side are provided. By changing the ratio, the gear ratio by the automatic transmission 41 is determined. The automatic transmission 41 is further provided with a final gear 415, whereby the driving force after shifting by the pulleys 412 and 413 is finally decelerated. In the power transmission device 1 having such a configuration, the driving force generated by the engine 11 is transmitted to the automatic transmission 41 via the torque converter 31 (and a planetary gear unit 21 described later), and the automatic transmission 41 performs a predetermined process. Is then transmitted to the left and right drive wheels 71, 71 via the final gear 415, the differential gear 51, and the drive shafts 61, 61.

  Here, in this embodiment, the planetary gear unit 21 is interposed between the engine 11 and the torque converter 31, and the clutch 215 provided in the planetary gear unit 21 is selectively connected / disconnected according to the traveling conditions of the vehicle. Thus, the close-up of acceleration generated in the vehicle during downshifting by the automatic transmission 41 is suppressed. In the present embodiment, the planetary gear unit 21 is positioned as an auxiliary transmission element of the power transmission device 1 separately from the automatic transmission 41 as the main transmission element, and includes a single carrier type planetary gear. Yes.

The planetary gear unit 21 includes a ring gear 211, a pinion gear 212, and a sun gear 213. Among these, the ring gear 211 is connected to the crankshaft of the engine 11 and the pinion gear 212 (specifically, a plurality of pinion gears). A carrier 221) to be coupled is connected to the input shaft of the torque converter 31. When the remaining sun gear 213 is connected to the housing 231 of the planetary gear unit 21 via the one-way clutch 214, the relative rotation of the sun gear 213 with respect to the housing 231 is restricted, and the crankshaft of the engine 11 and the input of the torque converter 31 are controlled. The shaft is connected in a decelerated state via a ring gear 211 and a pinion gear 212. In addition, the planetary gear unit 21 includes a clutch 215 configured to be able to connect the ring gear 211 and the sun gear 213 (which allows the three gears 211 to 213 to be rotated together). A rotating mass body 216 having a predetermined inertial mass is coupled to the sun gear 213 coaxially therewith. In the present embodiment, the rotating mass body 216 is formed in a disk shape, and the inertia moment Iw generated thereby is adjusted so as to balance the inertia moment I generated by the rotation element on the engine 11 side, and the inertia mass _mi is The reduction ratio of the planetary gear unit 21 via the ring gear 211 and the pinion gear 212 is set to be substantially equal to (a-1) × m as represented by the following equation (1). In the following equation (1), m is the inertial mass of the rotating element on the engine 11 side.

m _i ≒ (a-1) x m (1)
In the present embodiment, the one-way clutch 214 that restricts the relative rotation of the sun gear 213 to which the rotating mass body 216 is coupled functions as a brake provided for the “third gear”. As such a brake, in addition to the one-way clutch 214, various brakes such as a multi-plate brake can be employed. Further, the three gears 211 to 213 constituting the planetary gear according to the present embodiment may have the same configuration as that normally provided as a single carrier type planetary gear.

  Engagement and release of the clutch 215 are controlled by the AT control unit 201. The AT control unit 201 corresponds to a “control unit” according to the present invention, and executes a predetermined calculation based on vehicle running conditions detected by various sensors described later, and activates the clutch 215. A command signal is output to a hydraulic actuator (not shown).

  The AT control unit 201 includes a signal from the vehicle speed sensor 205 for detecting the vehicle traveling speed VSP, a signal from the inhibitor switch 206, and a transmission for the purpose of gear shifting control by the automatic transmission 41 and the engagement and disengagement of the clutch 215. A signal from an oil temperature sensor 207 for detecting the temperature TF of the hydraulic oil is input, and an accelerator opening APO and an engine speed NE are input from the engine control unit 101. The AT control unit 201 refers to the trend map data shown in FIG. 2 based on the input vehicle speed VSP and the accelerator opening APO, and the region R where the accelerator opening APO is equal to or greater than a predetermined value APO1 corresponding to the vehicle speed VSP. When it is, the command signal for releasing the clutch 215 is output. In addition to the hydraulic actuator of the clutch 215, the AT control unit 201 applies to the hydraulic actuators of the input side pulley 412, the output side pulley 413 and the forward clutch 411 of the automatic transmission 31, and the lockup clutch 311 of the torque converter 31. Command signal. The AT control unit 201 sets the automatic transmission 41 to a predetermined shift speed according to the driving conditions based on the vehicle speed VSP and the accelerator opening APO, and idle neutral control for releasing the forward clutch 411 during idling, and high speed Lock-up control for engaging the lock-up clutch 311 during cruise is executed. The engine control unit 101 controls the engine 11, a signal from the accelerator sensor 105 that detects an operation amount of the accelerator pedal (that is, an accelerator opening degree), a unit crank angle or a reference crank angle from the crank angle sensor 106. Each signal, a signal from the water temperature sensor 107 that detects the temperature TW of the engine cooling water, and the like are input, and a predetermined calculation related to engine control is executed. The accelerator opening APO is an index generally adopted as a required load for the engine 11. The release of the clutch 215 may be performed in response to a downshift command to the automatic transmission 41 by, for example, the AT control unit 201 in addition to the accelerator opening APO.

Next, operation | movement of the power transmission device 1 which concerns on this embodiment is demonstrated with the time chart shown in FIG.
FIG. 3 is a time chart showing a change in the acceleration α of the vehicle when accelerating by an accelerator operation from steady running in a high speed range (FIG. 2) equal to or higher than a predetermined vehicle speed VSP1. As by the planetary gear unit 21 according to the present embodiment (hereinafter referred to as "Embodiment 1".) By the solid line A, the inertial mass m _i of the rotating mass 216 smaller than in the present embodiment (m i _<(a-1 ) × m) that is set (hereinafter referred to as "embodiment 2". as by a dotted line B), larger than in the embodiment of the inertial mass _{m i (m i> (a} -1) × m) that set (Hereinafter referred to as “form 3”) is indicated by a two-dot chain line C, and a case of a general power transmission device having no planetary gear unit 21 is indicated by a solid line Z as a comparative example. In the comparative example, the automatic transmission and the torque converter are subjected to the same shift control and lockup control as in the present embodiment.

  First, in the case of a general power transmission device, the acceleration α rises with a delay from the time t0 when the accelerator pedal is depressed. As shown in the drawing, the acceleration α It shows a negative value temporarily. The phenomenon called acceleration α closing is that the downshift of the automatic transmission 41 accompanying the accelerator operation does not deviate from the control lockup region as a running condition, and the state where the lockup clutch 311 is engaged is maintained. This is because the inertial resistance acting on the engine 11 is large and the engine rotation does not rise rapidly.

  On the other hand, in the case of the mode 1, when the accelerator pedal is depressed, the traveling condition is satisfied (even if the lock-up clutch 311 is kept engaged without departing from the lock-up region). The region R on the map data shown in FIG. 2 is entered, and the clutch 215 of the planetary gear unit 21 is released. As a result, in the first mode, the engine 11 is separated from the downstream rotary elements such as the torque converter 31 with respect to the downshift, and therefore, as shown by the solid line A, the acceleration α is delayed with respect to the accelerator operation. However, there is no shrinkage as seen in the comparative example, and the acceleration α rises smoothly without taking a negative value from α = 0.

On the other hand, in the case of Form 2, after the time t0 when the accelerator pedal is started to be depressed, the acceleration α increases within a short time and reaches the target acceleration α. However, in form 2, the close-up is promoted and the acceleration α immediately after the accelerator operation is drastically decreased. This is due to the greatly reduced as compared with the inertial mass m _i of the rotating mass 216 to that of Embodiment 1. By adjusting the inertial mass m _i, although some shrinkage remains, it is possible to achieve both the acceleration.

Further, in the case of the form 3, as in the case of the form 1, it is possible to completely suppress the closing of the acceleration α. However, in the embodiment 3, by which excessive increase inertia mass m _i of the rotating mass 216, and Kitashi a sharp rise in the acceleration alpha immediately after the accelerator operation, together with cause protrudes acceleration alpha, acceleration The time until α reaches the target acceleration α1 after the accelerator operation is extended.

As described above, according to the present embodiment, the following effects can be obtained.
First, the ring gear 211, the pinion gear 212, and the sun gear 213 are rotated together by engaging the clutch 215 of the planetary gear unit 21 under traveling conditions that require high driving force transmission efficiency, such as during high-speed cruises. The transmission loss by the planetary gear unit 21 can be eliminated.

Secondly, when a downshift is performed by an accelerator operation or the like, by releasing the clutch 215, the engine 11 can be separated from the downstream rotating element, and a smooth increase in engine rotation can be ensured.
Third, the sun gear 213 as the "third gear", that was allowed with a rotary mass body 216 to adjust the inertial mass m _i, the inertia energy which holds this rotating mass 216 during a downshift, the engine 11 and the inertial resistance against the acceleration α can be satisfactorily suppressed. This will be described with reference to a collinear diagram as follows.

FIG. 4 shows the relationship between the rotational speeds of the ring gear 211 (R), pinion gear 212 (shown as carrier C), and sun gear 213 (S) in the planetary gear unit 21 when the clutch 215 is engaged and released. Yes. The one at the time of fastening is indicated by a dotted line L0, and the one at the time of releasing is indicated by a solid line L1.
In FIG. 4, when the clutch 215 is engaged, the ring gear R, the carrier C, and the sun gear S rotate together, so that their rotational speeds coincide as indicated by the dotted line L0. When the clutch 215 is released by the accelerator operation, these rotational speeds are determined by the connection relationship between the input shaft and output shaft of the planetary gear unit 21 and the housing 231. Since the output side and the output side are coupled in a decelerating state, the rotational speed of the ring gear R connected to the input shaft is increased with respect to the carrier C connected to the output shaft, while being connected to the housing 231. The rotational speed of the sun gear S will decrease. Here, the rotational speed of the carrier C tends to decrease due to the action of the inertial resistance generated by the downstream rotational element, but the rotating mass body 216 holds the inertial energy, which is converted into the kinetic energy of the carrier C. As a result, as indicated by a two-dot chain line L2, a decrease in the rotational speed is suppressed, and the close-up of the acceleration α is suppressed.

Fourth, by fastening the clutch 215, the inertial mass of the entire rotating element including the rotating mass body 216 is ensured and rotational fluctuation is suppressed, so that idling can be stabilized.
In the above, the case where the input shaft and the output shaft of the planetary gear unit 21 are connected in a decelerated state by setting the ring gear 211 on the input side and the pinion gear 212 on the output side has been described. The present invention is not limited to this. For example, as a modification, the sun gear 213 is set on the input side, the pinion gear 212 is set on the output side, and the ring gear 211 is connected via a brake such as a one-way clutch. You may make it connect to the housing 231. As another modification, the planetary gear unit 21 may be a dual carrier type, the sun gear 213 may be set on the input side, and the ring gear 211 may be set on the output side. In this case, the rotary mass body 216 is coupled to the pinion gear 212, and the pinion gear 212 is connected to the housing 231 via a brake. According to the former example, since the rotating mass body 216 is coupled to the ring gear 211 far from the rotating shaft, the relatively small rotating mass body 216 that suppresses the inertial mass has sufficient inertia to suppress the closing. Moments can be generated. Further, according to the former example, the gear ratio by the planetary gear unit 21 can only be a value larger than 2, whereas according to the latter example, the distance between the rotating mass body 216 and the rotating shaft is secured, A gear ratio smaller than 2 can be realized while suppressing the weight of the planetary gear unit 21.

  Further, in the above, in order to facilitate understanding of the contents, the downshift accompanying the acceleration in which the closing phenomenon becomes remarkable has been described. However, the present invention is not limited thereto, and the main transmission of the automatic transmission 41 and the like is not limited thereto. It can contribute to the improvement of drivability in that it allows the rotational speed on the input side of the speed change element to be raised smoothly without the adverse effect of promoting rotational fluctuations at low speeds. .

The torque converter 31 is not necessarily required for the power transmission device 1.
The “torque converter” used above includes a so-called fluid coupling having no stator.

Configuration of a vehicle power transmission device according to an embodiment of the present invention Clutch engagement area according to the embodiment Time chart showing change in acceleration α when accelerating by accelerator operation from steady running A collinear chart showing the relationship of the rotational speed of each gear when the clutch is engaged or disengaged

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Power transmission device, 11 ... Engine, 21 ... Planetary gear unit, 211 ... Ring gear, 212 ... Pinion gear, 213 ... Sun gear, 214 ... One-way clutch, 215 ... Clutch, 216 ... Rotating mass body, 221 ... Carrier, 231 ... housing, 31 ... torque converter, 311 ... lock-up clutch, 41 ... automatic transmission, 411 ... forward clutch, 412 ... input pulley, 413 ... output pulley, 414 ... metal belt, 415 ... final gear, 51 ... differential , 61 ... drive shaft, 71 ... drive wheel, 101 ... engine control unit, 201 ... AT control unit.

Claims (9)

An engine that is a driving source of the vehicle;
A planetary gear unit that is disposed on the output side of the engine, the input shaft is connected to the crankshaft of the engine, and the output shaft is connected to the drive wheels of the vehicle;
In the planetary gear unit, the input shaft is connected to any one of a ring gear, a pinion gear, and a sun gear of a planetary gear, and the output shaft is a gear other than the gear to which the input shaft is connected. Connected to either
The planetary gear unit is
A housing;
A clutch configured to be able to connect at least two of the three gears of the ring gear, the pinion gear, and the sun gear;
A brake for restricting rotation of the third gear with respect to the housing excluding two gears to which the input shaft or the output shaft is connected among the three gears;
A vehicle power transmission device comprising: a rotating mass body coupled to the third gear for generating a predetermined moment of inertia.   The power transmission device for a vehicle according to claim 1, wherein the input shaft and the output shaft are connected to a ring gear, a pinion gear, or a sun gear so as to obtain a reduced output with respect to a driving force from an engine.   When the transmission ratio by the planetary gear unit is a and the inertial mass of the rotating element on the engine side is m, the rotary mass body has an inertial mass substantially equal to (a-1) × m, or The power transmission device for a vehicle according to claim 2, which is larger than this.   The planetary gear unit is further included as an auxiliary transmission element of the vehicle, and further includes an automatic transmission provided as a main transmission element for determining a transmission ratio between the crankshaft of the engine and the drive wheels. The vehicle power transmission device according to any one of claims 1 to 3. Means for detecting the driving conditions of the vehicle;
The vehicle power transmission device according to any one of claims 1 to 4, further comprising: a control unit that controls engagement and disengagement of the clutch based on a traveling condition of the vehicle detected by the means. The detection means detects a required load on the engine as a running condition of the vehicle,
The power transmission device for a vehicle according to claim 5, wherein the control unit releases the clutch when the detected required load is larger than a predetermined load. In what comprises an automatic transmission as a speed change element other than the planetary gear unit,
The vehicle power transmission device according to claim 5 or 6, wherein the control unit releases the clutch in response to a downshift request to the automatic transmission.   The power transmission device for a vehicle according to any one of claims 1 to 7, wherein the planetary gear unit is disposed between the engine and a torque converter.   The power transmission device for a vehicle according to any one of claims 1 to 8, wherein the planetary gear unit is disposed between the engine and a forward clutch.

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