JPH0788894B2 - Torque detector for automatic transmission - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detection device for detecting a rotational torque transmitted to an output shaft of an automatic transmission used in a vehicle, and more particularly, to a rotational torque of the output shaft accurately. It is designed to detect.

[Conventional technology]

As a conventional torque detecting device for an automatic transmission, there are, for example, those described in JP-A-61-127952 and JP-A-61-127953.

In this conventional example, one or a plurality of torque detectors each having a built-in torque detecting element are fitted to a rear end portion of a transmission case of a vehicle, a fitting structure, a rib and a screw structure for engaging with the rib.
Alternatively, it is attached by a flange structure, and the detection surface of the torque detector is opposed to the output shaft extending from the transmission case with a predetermined distance in the circumferential direction. The torque detector has a configuration in which an exciting coil and a detection coil are wound around a substantially U-shaped magnetic core, and the outer peripheral surface of the output shaft facing the torque detector is
In order to improve the detection sensitivity, a thin film (ribbon) having a thickness of 20 to 30 μm made of a magnetically permeable member such as amorphous is adhered with a heat resistant adhesive.

[Problems to be solved by the invention]

However, in the above-described conventional torque detecting device for an automatic transmission, since the torque detecting head in which the exciting coil and the detecting coil are wound around the magnetic core is used as the torque detector, the mounting position of the torque detecting head is the transmission. It is limited to the rear extension that is connected to the outside and cannot be installed in the transmission case. If there is a rear extension, there is no problem, but it is not necessary for the auxiliary transmission or the four-wheel drive after the automatic transmission. When the transfer is directly connected, there is a problem that the torque detector cannot be provided. Further, in order to detect the torque fluctuation due to the gear shift shock that occurs when the hydraulic pressure is applied to each engagement element to perform a gear shift, the final stage of the engagement element of the output shaft, that is, the position near the rotational force transmission portion with respect to the output shaft is detected. The most accurate torque detection can be performed by detecting with.When the torque is detected outside the transmission case as in the above-mentioned conventional example, a shift shock detection delay occurs and accurate shift shock prevention control is performed. There was also a problem that it could not be done.

Therefore, the present invention has been made by paying attention to the problems of the above-mentioned conventional example, and by performing the torque detection of the output shaft in the transmission case, the automatic shift capable of solving the problems of the above-mentioned conventional example. An object is to provide a torque detection device for a machine.

[Means for solving problems]

The driving force from the engine is transmitted through the input shaft, and the driving force is automatically changed to be connected to the output side of the transmission case by appropriately selecting a plurality of fastening elements arranged in the transmission case. In an automatic transmission that transmits to an output shaft that extends to the outside through a rear extension, a cylindrical member that extends inward facing the output shaft is fixed to an end plate portion formed on the output side of the transmission case, A torque detecting surface having a shape magnetic anisotropy is formed on the outer peripheral surface of the output shaft in the transmission case, on the rear side of the final stage of the fastening element and facing the cylindrical member, and faces the torque detecting surface. A torque detector having a detection coil is attached to the cylindrical member.

[Action]

In the present invention, the torque detection surface is formed by directly giving the shape magnetic anisotropy to the circumferential surface of the output shaft or by adhering a thin film having the shape magnetic anisotropy, and facing the same. By disposing a torque detector including a flat detection coil, the magnetic permeability of the torque detection surface changes due to the tensile force or compression force due to the torque acting on the torque detection surface in the torque detector. The change is detected by the detection coil. As described above, since it is only necessary to provide the detection coil as the torque detector, it is possible to dispose the torque detector in a slight gap between the output shaft in the transmission case and the transmission-side cylindrical member facing the output shaft. Therefore, it is possible to accurately detect a torque fluctuation such as a shift shock transmitted to the output shaft.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of an automatic transmission showing an embodiment of the present invention.

In the figure, reference numeral 1 denotes a transmission case, a torque converter housing 2 is integrally connected to a front end side thereof, and a rear extension 3 is integrally connected to a rear end side thereof.

An oil pump housing 4 and an oil pump cover 5 are arranged between the transmission case 1 and the torque converter housing 2, and the input shaft 6 is inserted into the transmission case 1 through the cylindrical portion of the oil pump cover 5. There is.

A turbine 7t of a torque converter 7 is spline-coupled to a position inside the torque converter housing 2 of the input shaft 6, and a sun gear 8a of a rear planetary gear 8 is fixed to a rear end portion of the transmission case 1.

Then, as schematically shown in FIG. 4, the planet carrier 8c of the rear planetary gear 8 is connected to the internal gear 9d of the front planetary gear 9.

On the other hand, a high clutch 10 is interposed between the input shaft 6 and a planet carrier 9c of the front planetary gear 9, and a reverse clutch 11 is interposed between the input shaft and a sun gear 9a of the front planetary gear 9.

Further, the forward one-way clutch 12, the forward clutch 13 and the overrun clutch 14 are inserted in parallel between the internal gear 8d of the rear planetary gear 8 and the planet carrier 9c of the front planetary gear 9, and the forward planetary gear 9 is inserted. A low and reverse brake 15 and a low one-way clutch 16 are connected in parallel between the planet carrier 9c of the gear 9 and the fixed portion.

Meanwhile, the planet carrier 8c of the rear planetary gear 8
An output shaft 17 coaxially arranged with the input shaft 6 is spline-connected, and the output shaft 17 is connected to a propeller shaft (not shown) through the rear extension 3.

The output shaft 17 is an end plate portion of the transmission case 1.
A cylindrical member 20 rotatably supported by a Newle bearing 18 inserted between the cylindrical member 20 and the end plate 1a, which extends in the transmission case 2 so as to face the output shaft 17.
Is stuck.

A torque detection device 30 that detects the rotational torque transmitted to the output shaft 17 is arranged between the output shaft 17 and the cylindrical member 20.

That is, as shown in FIGS. 2 and 3, the torque detection device 30 has a torque detection surface 30 formed on the outer peripheral surface of the output shaft 17.
A, a torque detector 30B composed of a coil facing the torque detection surface 30A, and a measuring unit 30C that measures a rotational torque based on a detection signal of the torque detector 30B.

The torque detection surface 30A is formed on the outer peripheral surface of the small diameter portion 31 formed at a position near the front end that is spline-coupled to the planet carrier 8c of the rear planetary gear 8 in which the rotational torque is transmitted to the output shaft 17 in the transmission case 1. , A first groove row 32A (see FIGS. 2 and 6) consisting of a plurality of grooves a, ..., A and a second groove b ,. Groove row 32B (No.
(See Figures 2 and 6).

Further, each of the grooves a, ..., A has an inclination angle of +45 degrees with respect to the axial direction of the output shaft 17 (see arrow A in FIG. 2) (where the axial direction is the reference axis, From now on, it is assumed that the counterclockwise direction is positive and the clockwise direction is negative), while each of the grooves b, ..., b has a predetermined depth (for example, 1 mm) with an inclination angle of -45 degrees. Are formed at equal intervals.

By providing the grooves a, ..., A and b, ..., B, the first and second groove rows 32A, 32B are provided between the grooves a ,. ..., b small part 31 between each other
A ', ..., a' on the line as part of the peripheral surface of the
, B ′, ..., B ′ are formed (see FIG. 6). The ridges a ′, ..., A ′ and b ′, ..., B ′ each have a predetermined magnetic flux φ for torque detection described later in the axial direction of the shaft (45 degrees in this embodiment). (See the dotted line in FIG. 6), which enables the first and second groove rows 32A and 32B of the small diameter portion 31 to have different shape magnetic anisotropies. .

Therefore, the groove length, the groove width, and the groove interval for each of the grooves a, ..., A and b, ..., B are set to predetermined values that can secure the above-described shape magnetic anisotropy.

Actually, the groove rows 32A and 32B of the torque detection surface 30A are output shafts.
When 17 is formed, it is formed by cutting using a cutting machine such as a hobbing machine.

Here, the first and second groove rows 32A and 32 in the present embodiment.
B is set so as to have a so-called positive magnetostriction property in which the magnetic permeability increases when subjected to tensile deformation.

On the other hand, the torque detector 30B includes first and second coils 33A and 33B for exciting and detecting, which are closely opposed to each other in the groove rows 32A and 32B with a gap of a predetermined distance, and these coils 33A and 33B are wound. It is configured to have first and second yokes 34A and 34B which are held and fixedly arranged on the inner peripheral surface of the cylindrical member 20.

On the other hand, the measuring unit 30C described above is configured as shown in FIG. To explain this in detail, in the figure, 40 is the first,
It is a bridge circuit of the second coils 33A and 33B and resistors (resistance values R ₁ and R ₂ ) 41A and 41B. In this bridge circuit 40,
The inductance L ₁ of the first coil 33A is a value including the inductive inductance of the first groove row 32A, and similarly, the inductance L ₂ of the second coil 33B is the second groove row 3A.
It is a value including the induction inductance of 2B. The AC power supply 42 is connected to the input ends a and b of the bridge circuit 40, while the output ends c and d are connected to the signal processing unit 43 that processes the detection signal. Here, the frequency of the AC power supply 42 is set to a value (for example, about 10 kHz to 30 kHz) sufficient to generate a so-called skin effect, in which the magnetic flux passing through the groove rows 32A and 32B is distributed only on the surface thereof. .

In addition, the signal processing unit 43 uses the rectifier circuits 44A and 44B that convert the detection signals from the output terminals c and d of the bridge circuit 40 into direct current, the output of the rectifier circuit 44A as positive, and the output of the rectifier circuit 44B as negative. A differential amplifier 45 that takes the difference between them and amplifies and outputs the amplified signal as a torque detection signal is configured.

Here, in the present embodiment, the inductances L ₁ and L ₂ of the bridge circuit 40 are set so that L ₁ = L ₂ in the state where the rotational torque is not transmitted to the output shaft 17, and thus this state Then, the resistance values R ₁ and R _{2 of the} resistors 41A and 41B are set so that the output of the bridge circuit 40 becomes zero, that is, the balanced state.

Next, the operation of the above embodiment will be described.

First, when the select lever (not shown) is set to the neutral range or the parking range, both the forward clutch 13 and the reverse clutch 11 are controlled to the open state, and the rotational force from the engine input to the input shaft 6 is It is not transmitted to the output shaft 17, and the output rotational torque remains zero. In this case, when the AC power supply 42 of the measuring unit 40B is turned on and an AC current of a predetermined frequency is supplied to the first and second coils 33A and 33B, a magnetic closed circuit as shown by the dotted line in FIG. 7 is formed. It

That is, looking at the magnetic circuit applied to the first coil 33A, each magnetic flux φ passes through the first yoke 34A, the air gap, and the first groove row 32A, and again becomes a path through the air gap and the first yoke 34A. The same applies to the magnetic circuit of the second coil 33B.

At this time, the magnetic fluxes Φ, ..., Φ in the first and second groove rows 32A, 32A are due to the skin effect, the surface portions of the first and second groove rows 32A, 32B, that is, the grooves a. , ...,
Line-shaped ridges a'between a and b, ..., b
, A ′ and b ′, ..., B ′ and pass through with an inclination angle of 45 degrees, which is positive or negative with respect to the axial direction (see the dotted line in FIG. 6). In this state, since the inductance L ₁ = L ₂ as described above, the AC outputs of the output terminals c and d of the bridge circuit 40 have the same phase and the same potential. Therefore, the DC outputs of the rectifier circuits 44A and 44B are equal to each other, the output value of the differential amplifier 45 becomes zero, and the rotational torque with respect to the output shaft 17 is displayed.

From this state, when the drive range or 2 range is selected with the select lever to start the vehicle, the forward clutch 13 and the overrun clutch are correspondingly selected.
With 14 engaged, forward one-way clutch
The rotation force from the engine transmitted to the input shaft 6 is transmitted to the output shaft 17 via the sun gear 8a of the rear planetary gear 8, the pinion gear 8b, and the planet carrier 8c. , Output shaft
17 starts forward rotation. This allows the first groove row
32A is subjected to compressive deformation in the direction indicated by-in Fig. 6,
On the other hand, the second groove row 32B undergoes tensile deformation in the direction shown by-in the figure. By this deforming action, in the first groove row 32A, the magnetic permeability is reduced, the magnetic fluxes φ, ..., φ passing therethrough are reduced, and eventually the inductance L ₁
Is reduced. On the other hand, in the second groove row 32B, the magnetic permeability increases, and the magnetic flux φ passing therethrough is ...
φ increases, and eventually the inductance L ₂ increases.

Therefore, in the bridge circuit 40 of the measuring unit 30C, the balance is lost, and the voltage at the output end c-b side becomes higher than that at the output end db side. Therefore, in the signal processing unit 43, the output of the rectifier circuit 44A is the rectifier circuit 44B.
And the differential amplifier 45 outputs a rotational torque detection signal indicating a positive value.

On the other hand, if you select the reverse range with the select lever,
When the reverse clutch 11 is engaged, the low and reverse brake 14 acts, and the rotational force transmitted to the input shaft causes the reverse clutch 11, the sun gear 9a of the front planetary gear 9, the pinion gear 9b, the internal gear 9d and the rear planetary gear. It is transmitted to the output shaft 17 via the planet carrier 8c of the Lee gear 8, and the output shaft 17 rotates in the reverse direction. As a result, the first groove row 32A undergoes tensile deformation in the direction indicated by-in FIG. 6, and the second groove row 32B undergoes compressive deformation in the direction indicated by-in FIG. As a result, the inductance L ₁ increases because the magnetic permeability increases in the first groove row 32A, while the inductance L ₂ decreases because the magnetic permeability decreases in the second groove row 32B.

Therefore, in the bridge circuit 40 of the measuring unit 30C, the output end d
The voltage of the −b side output becomes higher than that of the output end c−b side output. Therefore, in the signal processing unit 43, the output of the rectifier circuit 44B becomes larger than the output of the rectifier circuit 44A, and the differential amplifier 45 outputs a torque detection signal having a negative value.

Therefore, when the above-mentioned measurement is executed for various rotational torques for each rotational direction of the output shaft 17, the value of the rotational torque applied to the output shaft 17 and the magnetic permeability of the first and second groove rows 32A, 32B are measured. Since there is a proportional relationship with the value, the result shown in FIG. 8 is obtained. That is, when the rotation torque is zero, the output voltage of the signal processing unit 43 becomes zero, and when the rotation torque is applied in the right rotation direction or the left rotation direction from this state, a positive or negative value proportional to the torque value is obtained. The output voltage is obtained. That is, the magnitude of the rotational torque input to the output shaft 17 can be known from the value of the output voltage, and the direction of application of the rotational torque can be known from the positive / negative of the output voltage. By performing feedback control of the engagement element such as the clutch, it is possible to prevent shift shock and perform optimum shift control. In particular, since the rotation torque of the output shaft can be detected in the vicinity of the portion to which the rotation torque is transmitted, the rotation torque can be accurately detected and the response delay in feedback control can be reduced. .

The present embodiment has various advantages because it is constructed and operates as described above.

First, the torque detection surface 30A has grooves a, ..., A and b, ..., B directly formed on the outer peripheral surface of the small diameter portion 31 of the output shaft 17,
As a result, since the output shaft 17 is composed of a single member that utilizes the magnetic characteristics of the output shaft 17, the processing steps are simplified, the cost can be reduced, and the mechanical process can be reduced as compared with the case where the magnetostrictive thin film is attached. It is also robust and does not have different coefficient of thermal expansion between members, as in the case of a composite member that adheres a magnetostrictive thin film, the temperature characteristics are improved, and the torque detection surface 30A is Since they are formed over the circumferential surface of a predetermined area, their detection outputs are averaged in the circumferential direction, and they are directly affected by local magnetic characteristic disturbances such as structural defects inside the output shaft 17. In addition, even if the output shaft 17 is eccentric, the effect of this eccentricity error can be canceled by both sides of the output shaft 17, so that the torque detection accuracy can be significantly improved.

Further, in the present embodiment, the torque detection surface 30A is configured such that the two groove rows 32A and 32B receive the deformation forces in the opposite directions with respect to the rotational torque, so that output signals of opposite polarities are obtained. As a result, the range width of the detection signal with respect to the change in torque can be set large, and both the right rotation direction and the left rotation direction can be detected while maintaining the above-described high accuracy.

Furthermore, in this embodiment, the first and second coils 33A, 33B are used.
Since it is configured to be used for both excitation and detection,
The size can be further reduced as compared with the case where both coils are separately wound.

In addition, in the above-described embodiment, the case where the first and second groove rows 32A and 32B are provided as the torque detection surface has been described, but the present invention is not necessarily limited to this, and for example, The configuration can be simplified by using only one of them, and in that case, one or both of the rotational torques can be appropriately measured depending on how the bridge circuit 40 of the measuring unit 30C is assembled. On the other hand, in the above case,
When there is enough mounting space, torque detection surface 30A
By providing a plurality of sets of the torque detectors 30B and the shape detectors of the torque detectors 30B, the detection output may be increased and the detection accuracy may be further improved.

Further, in the above-described embodiment, the grooves a, ..., A and b,
.., b are set to +45 degrees and −45 degrees, respectively, but the present invention is not necessarily limited to this. For example, the tilt angles may be opposite to each other, and machining etc. It may be an angle other than 45 degrees as required.

Furthermore, in the above-described measuring unit 30C, the case of measuring the output voltage according to the rotation torque has been described, but the output voltage is digitized and processed by the microcomputer,
It is also possible to perform power train shift control.

By the way, in the present invention, the groove is provided obliquely as the magnetic flux direction defining means constituting the shape magnetic anisotropy,
As a modification of this, a groove-shaped non-magnetic member may be embedded to reduce leakage of magnetic flux and to ensure more secure passage of magnetic flux in an oblique direction.

Further, in the above embodiment, the case where the torque detection surface is directly formed on the output shaft has been described, but the present invention is not limited to this, and a thin film having an amorphous slit array is attached to the output shaft 17. You may do it.

Further, not only when the rectifier circuits 44A and 44B are applied as the measuring unit, but when the AC differential amplifier is applied as the differential amplifier, the output terminals c and d of the bridge circuit 40 are directly input to the differential amplifier. The bridge circuit 44 may be connected to the side, as long as it is configured so that the balanced state and the unbalanced state of the output terminals c and d of the bridge circuit 44 can be detected.

Furthermore, the automatic transmission is not limited to the configuration of the above embodiment, and the present invention can be applied to an automatic transmission having any other configuration.

〔The invention's effect〕

A cylindrical member extending inwardly facing the output shaft is fixed to an end plate formed on the rear extension side of the transmission case, and the final stage of the fastening element of the output shaft in the transmission case and in the output case. A configuration in which a torque detection surface having a shape magnetic anisotropy is formed on the outer peripheral surface on the further rear side and opposed to the cylindrical member, and a torque detector having a detection coil is mounted on the cylindrical member opposed to the torque detection surface. Therefore, it becomes possible to detect the rotational torque transmitted to the output shaft in the vicinity of the transmission part, and it occurs when the rotational torque transmitted to the output shaft in a non-contact state and the fastening element of the automatic transmission are fastened. It is possible to accurately detect the shift shock that occurs, and to reduce the detection delay of the rotational torque. It is possible to provide a suitable torque detector when using a click detection value performs a shift control of the automatic transmission.

Further, since the torque detector of the output shaft is arranged in the transmission case, the torque of the output shaft can be reliably detected even when the auxiliary transmission or the transfer is directly connected to the rear side of the automatic transmission. .

Further, since the torque detection device can be arranged in a narrow space, the total length of the transmission case does not become long, and a special bracket or the like is required when mounting the torque detector on the transmission case side cylindrical member. In addition, since the output shaft and the transmission case side cylindrical member are arranged concentrically, the gap between the detection coil of the torque detector and the torque detection surface can be maintained uniformly.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a partially enlarged view of an essential part of FIG. 1, FIG. 3 is a sectional view taken along line III-III of FIG. 2, and FIG. Fig. 1 is a schematic diagram of the automatic transmission, Fig. 5 is a block diagram showing an example of a measuring unit, Fig. 6 is a development view showing a torque detection surface formed on an output shaft, and Fig. 7 is a magnetic field generated by a coil. FIG. 8 is a characteristic diagram showing the relationship between torque and output voltage of the torque detection device. In the figure, 1 is a transmission case, 6 is an input shaft, and 8
Is a rear planetary gear, 9 is a front planetary gear, 10 is a high clutch, 11 is a reverse clutch, 12 is a forward one-way clutch, 13 is a forward clutch, 14 is an overrun clutch, 15 is a low and reverse brake, and 16 is a low clutch. One-way clutch, 17 is an output shaft, 20 is a cylindrical member, 30A is a torque detecting surface, 30B is a torque detector, 30C is a measuring unit, 32A and 32B are groove rows, 33A and 33B are coils, 40 is a bridge circuit, and 45 is a It is a differential amplifier.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroyuki Hirano 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Kunihiko Morikawa 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. ( 72) Inventor Hisashi Kitahara, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture, Nissan Motor Co., Ltd. (72) Masaki Sugimoto, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (56) Reference: JP-A-61 -127953 (JP, A)

Claims (1)

[Claims] 1. A drive force from an engine is transmitted through an input shaft, and the drive force is automatically changed by appropriately selecting a plurality of fastening elements arranged in the transmission case to automatically shift the transmission case. In an automatic transmission that transmits to an output shaft that extends to the outside through a rear extension that is connected to the output side, a cylinder that extends inward facing the output shaft at an end plate portion formed on the output side of the transmission case. A member is fixed, and a torque detecting surface having a shape magnetic anisotropy is formed on the outer peripheral surface of the output shaft in the transmission case and on the rear side of the final stage of the fastening element and facing the cylindrical member, A torque detector having a detection coil is mounted on the cylindrical member facing the torque detection surface. Detection device.