GB2176861A - Device for automatically regulating tension applied to inner wire of control cable for slack adjustment - Google Patents

Abstract

A Bowden cable device for automatically regulating a tension applied to an inner wire 3 of a control cable 1, comprising: a conduit 2 and the inner wire 3 slidably inserted into the conduit 2; a cap member 4 having an end portion 4a being connected with an end of the conduit 2, having a hollow 9 into which the inner wire 3 is slidably inserted, and having a series of projections 8 on an outer peripheral surface 7 of the other end portion 7 of the cap member 4; a fixed casing 10 containing the cap member 4 so that the cap member can move within the casing in the axial direction; a first element 39 for urging the cap member toward the conduit side; at least one pawl member 18 having a pawl 20 capable of being engaged with the series of projections at or near a free end thereof; a second element 38 for urging the pawl member inwardly in the radial direction; a lock-releasing member 24 being slidably contained within the casing having a first associating portion 27 at an end thereof, and having a second associating portion 25, 26 capable of being associated with the pawl member 18 so that the free end leaves the series of projections; and a nipple 43 being fixed to the inner wire at the position where the inner wire comes out of the lock- releasing member 24 so as to being associated with the first associating portion 27. <IMAGE>

Description

SPECIFICATION Device for automatically regulating tension applied to inner wire of control cable The present invention relates to a device for automatically regulating a tension applied to an inner wire of a control cable (hereinafter referred to as a tension regulating device) and, more particularly, to a tension regulating device which can automatically cancel a looseness or an excessive tenseness occurring to an inner wire of a control cable and always automatically apply the most appropriate tension to the inner wire. Such a looseness occurs to the inner wire due to a rise (drop) in temperature, an occurence of a permanent elongation of the inner wire during the operation, or the like. Further, the excessive tenseness occurs to the inner wire due to a drop (rise) of temperature, a wear of members to the controlled, such as clutch plates, or the like.

Conventionally, a control cable is widely used as a means for remotely controlling an apparatus. The control cable fundamentally comprises a flexible conduit and a flexible inner wire comprising a strand of steel wires, which is slidably inserted into the conduit, and is constructed so as to transmit a load acted on one end of the inner wire to the other end.

An inertial force of such a control cable is lower than that of a rod, or the like, and, therefore, a loss of power to be transmitted is reduced. Further, the control cable can be arranged in the various curved states, since it has a flexibility. Such a control cable is used as the following form. That is to say, both ends of the conduit are fixed to frame(s) of a vehicle, or the like. One end of the inner wire is connected with an operating means such as a lever and the other end of the inner wire is connected with a driven apparatus such as a clutch device and a braking device. According to such a form, a pull load applied to the one end of the inner wire by operating the operating means is accurately transmitted to the driven apparatus via the other end of the inner wire so as to perform the remote operation.

On the other hand, when the inner wire comprising a strand of steel wires repeatedly receives tensions of heavy loads applied by operating the clutch device, the braking device, or the like, of a vehicle over a long period, a permanent elongation gradually occurs to the inner wire. Therefore, the inner wire is loosened and the operational force cannot be accurately transmitted to the driven side.

In order to absorb such a permanent elongation of the inner wire, a mechanism for making the length of the inner wire per se short, a mechanism for making the length of the inner wire short by making the length of the conduit long, or the like, is employed. In the former, an inner wire is divided into two parts. The two parts are respectively wound on two pulleys, which respectively have ratchets engaged with each other. Therefore, the length of the inner wire per se can be made short by rotating one pulley relative to the other pulley, so that the permanent elongation can be absorbed. In the latter, a screw mechanism is applied between an end of the conduit and a portion where the end of the conduit is supported or fixed. The length of the conduit is made long by operating the screw mechanism, so that the length of the inner wire can be made short relative to the length of conduit.As a result, the permanent elongation can be absored.

According to the above described mechanisms, the work for absorbing the elongation must be manually performed every time when the elongation occurrs to the inner wire and, therefore, the work becomes very troublesome. In order to resolve such a problem, Japanese Unexamined Utility Model Publications No. 79268/1976 and No. 21358/1977 disclose devices for automatically absorbing an elongation of an inner wire by using a oneway-clutch means comprising a ratchet, a pawl and a spring.

By the way, an elongation of the inner wire includes not only the above described permanent elongation, but also an elastic elongation which temporarily occurs to the inner wire only when the inner wire receives an external force. In case of such an elastic elongation, the inner wire returns to the original form by removing the external force. The above described devices using the one-way-clutch means have a problem that not only the permanent elongation but also the elastic elongation is absorbed. For example, when one of the devices is applied to a control cable for a clutch device, the device absorbs an apparent elongation of the inner wire due to a deformation of a chassis or a body of a vehicle during the running on a road, an elastic elongation of the inner wire due to an excessive tension applied to the inner wire during the operation, and the like.As a result of the fact, an excessive tenseness occurs to the inner wire and, further, two clutch plates opposited to each other are always incompletely engaged with each other, so that a burning due to a friction occurs to the clutch plates. Further, in case that one of the devices is applied to a control cable used in a braking device, the braking device is always acted due to the above described elongation and elastic elongation, so that a burning occurs to a brake lining.

On the other hand, when the clutch plates of the clutch device, or the brake lining of the braking device is gradually worn away, the inner wire is dragged out of the conduit or the length of the innex wire becomes unefficient relative to that of conduit, so that an excessive tension is applied to the inner wire, for example, when a clutch pedal is operated to the end position. Therefore, it is necessary to adjust so as to make the length of the inner wire long relative to the conduit. However, a tension regulating device which can automatically adjust so as to make the length of the inner wire long relative to the conduit is not known.

The object of the present invention is to provide a tension regulating device for an inner wire of a control cable which can automatically regulate a tension to be applied to the inner wire by automatically adjusting the length of the conduit, so that the length of the inner wire is made to be short relative to the conduit when an looseness occurs to the inner wire, and so that the length of the inner wire is made to be long relative to the conduit when an excessive tenseness occurs to it.

Another object of the present invention is to provide a tension regulating device for an inner wire of a control cable which is simplified in structure and can be surely operated.

According to the present invention, there is provided a device for automatically regulating a tension applied to an inner wire of a control cable, comprising: the control cable comprising a conduit and the inner wire slidably inserted into the conduit; a cap member having an end portion being connected with an end of the conduit, having a first hollow extending in the axial direction of the cap member for slidably inserting the inner wire, and having a series of projections on an outer peripheral surface of the other end portion of the cap member; a casing containing the cap member so that the cap member can move within the casing in the axial direction; a first means for urging the cap member toward the conduit side; at least one pawl member being rotatably supported at one end thereof within the casing, extending inwardly in the radial direction with respect to the cap member and toward the conduit side so that the free end approaches the series of projections, and having a pawl capable of being engaged with the series of projections at or near a free end thereof; a second means for urging the pawl member inwardly in the radial direction; a lock-releasing member being contained within the casing so that the lock-releasing member can siide in the axial direction, having a small opening into which the inner wire is slidably inserted, having a first associating portion at an end thereof, and having a second associating portion capable of being associated with the pawl member so that the free end leaves the series of projections; and a nipple being fixed to the inner wire at the position where the inner wire comes out of the lock-releasing member so as to being associated with the first associating portion.

When the inner wire is pulled toward a driven apparatus, i.e. in the direction of the conduit side, the second associating portion of the lock-releasing member pushes the pawl member outwardly in the radial direction, since the nipple pushes the lock-releasing member toward the driven apparatus side. As a result, the engagement between the pawl and the series of projections is released, so that the cap member becomes free from the casing.

In such a state, the cap member moves in the axial direction so that the tension applied to the inner wire, i.e. the compression applied to the conduit is balanced with a reaction of the first means for always urging the cap member toward the conduit side.

When the inner wire is pulled by an operating means, the second associating portion of the lock-releasing member becomes apart from the pawl member, since the nipple becomes apart from the first associating portion of the lock-releasing member. Therefore, the pawl member is rotated so that the pawl thereof is tightly engaged with the series of projections. As a result, the cap member is locked relative to the casing in the state that the tension of the inner wire is appropriately maintained.

Accordingly, the pull operation of the inner wire can be performed in the most appropriate tensional condition.

Further, the tension regulation of the inner wire of the control cable is automatically performed just after the operation is finished.

Therefore, even if a permanent elongation occurs to the inner wire, or even if the members of the driven apparatus are worn out, the tension of the inner wire of the control cable is automatically regulated in the most appropriate state, so that the device becomes free from maintenance.

The above and other objects and advantages of the present invnetion will become apparent from the following description with reference to the accompanying drawings.

Fig. 1 is a longitudinal sectional view showing an embodiment of a tension regulating device of the present invention; Fig. 2 is a partially sectional side view showing the device in Fig. 1 in the operating state; Fig. 3 is a partially cutaway exploded view in perspective of the device in Fig. 1; and Fig. 4 is a diagram showing an example of a form that the device of the present invention is applied to a control cable used in operating a clutch device of a vehicle.

In Fig. 1, numeral 1 indicates a control cable which comprises a conduit 2 and an inner wire 3 slidably inserted into the conduit 2. A cap member 4 possesses a first end portion 4a and a second end portion 7 extending from the first end portion 4a via a collar 6.

An end of the conduit 2 is connected with the first end portion 4a of the cap member 4, for example, by means of the following method.

That is to say, the end of the conduit 2 is inserted into an axially extending recess por tion 5 formed in the first end portion 4a of the cap member 4 and a periphery of the first end portion 4a is caulked to the end of the conduit 2. The second end portion 7 has a male screw portion 8, which is a series of projections, on at least a part of an outer peripheral surface of the second end portion 7. The cap member 4 has a hollow 9, into which the inner wire 3 is slidably inserted, extending in a central axis of the cap member 4. (The recess portion 5 is coaxial with the hollow 9.) The cap member 4 is contained within a casing 10 so that the cap member 4 can move in the axial direction. The casing 10 comprises a first cup-like portion 11 and a second cup-like portion 12. Those cup-like portions 11, 12 are connected with each other near their openings.

The second cup-like portion 12 has a tubular portion 13 extending from a bottom thereof in the axial direction.

An outer peripheral surface of the collar 6 of the cap member 4 is in contact with an inner peripheral surface 14 of the first end portion 11. The first cuplike portion 11 has a small opening 16, through which the first end portion 4a of the cap member 4 or the control cable 1 passes, at its bottom.

The second portion 12 has two bearing portions 1 7 opposite to each other near its bottom portion, as shown in Fig. 3. A pin 19 for rotatably supporting a pawl member 18 is supported on the bearing portion 17. The pawl member 18 extends from a pin 19 in the radial direction and toward the conduit 2 side, i.e. in the left side in Figs. 1 and 2, so that the free end of the pawl member can approach the screw portion 8.

The pawl member 18 has a pawl 20, inside a free end of the pawl member 18, as shown in Fig. 1. The pawl 20 can be engaged with the male screw portion 8 at an optional position in the range of the screw portion. The pawl member 18 has a first cam portion 21 shaped in a circular arc at its free end and a second cam portion 22 linearly inclined with respect to the axial direction of the cap member 18 at its inside portion, as shown in Fig.

1.

The tubular portion 13 of the second end portion 12 of the casing 10 has a guiding hollow 23 extending in the axial direction. A tubular member 24, having a bottom plate 27, for releasing the locking state of the cap member 4 relative to the casing 10 (hereinafter referred to as lock-releasing member) is slidably inserted into the guiding hollow 23.

The lock-releasing member 24 has a flange portion 25 for preventing the lock-releasing member 24 from coming out of the tubular portion 13, as shown in Fig. 1. Further, an outer periphery of the flange portion 25 is a second associating portion 26 being associated with the second cam portion 22 of the pawl member 18. The bottom plate 27 of the lock-releasing member 24 has a small opening 28 through which the inner wire passes. An outer end surface of the bottom plate 27 of the lock-releasing member 24 is a first associating portion being associated with a nipple 43 described later. The second end portion 7 of the cap member 4 is slidably guided within the lock-releasing member 24 so that the outer peripheral surface of the second end portion 7 is in contact with an inner peripheral surface 29 of the lock-releasing member 24.

Therefore, the cap member 4 can smoothly move in the axial direction since the collar 6 and the second end portion 7 are slidably supported or guided. A space 30 within the casing 10 is divided into two parts by a ring member 32 having an L-shaped section. The ring member 32 is contained within the second end portion 12 near a portion where the first cup-like portion 11 and the second cuplike portion 12 are connected with each other.

The ring member 32 is fixed within the casing 10 by locating a ring-shaped spacer 34 having a trapezoid-shaped section between the ring member 32 and the bearing portions, as shown in Fig. 1. The ring member 32 has an opening 35 through which the second end portion 7 of the cap member 4 passes.

The ring member 32 contains a piston 37 and a coil spring 38 which are a second means for always urging the pawl member 18 inwardly in the radial direction with respect to the axis of the cap member so that the pawl 20 approaches the male screw portion 20.

The piston 37 has a surface 36 being associated with the first cam portion 21 of the pawl member 18. The coil spring 38 is located between the ring member 32 and the piston 37.

Therefore, the piston 37 is always urged toward the first cam portion 21 of the pawl member 18 in the direction of Arrow A in Fig.

1.

A coil spring 39, which is a first urging means, is located between the collar 6 of the cap member 4 and the ring member 32 within the first cup-like portion 11, so that the cap member 4 is always urged toward the conduit 2 side, i.e. in the direction of Arrow B in Fig.

1.

In the embodiment of the device of the present invention shown in Fig. 1, a coil spring 41, which is a third urging means, is provided within an interior 40 of the lock-releasing member 24, so that the lock-releasing member 24 is always urged in the direction of Arrow A.

A male screw portion 42 is formed on an outer peripheral surface of the tubular portion 13 of the second end portion 12, so that the casing 10 can be fixed to a frame, or the like, of a vehicle.

The inner wire 3 is provided with a nipple at a position where the inner wire comes out of the opening 28 of the bottom plate 27 of the lock-releasing member 24.

The operation of the tension regulating device constructed as described above is described below.

The device shown in Fig. 1 can be applied to a control cable 1 for operating a clutch 51 of a vehicle, as shown in Fig. 4, or the like. In Fig. 4, one end of the conduit 2 of the control cable 1 is fixed to the cap member of the tension regulating device 53, as described above. The device 53 is fixed to a frame 52.

The other end of the conduit 2 of the control cable 1 is fixed to a frame 52b near the clutch 51. One end of the inner wire 3 of the control cable 1 is connected with a lower end portion of a clutch pedal 54. The other end of the inner wire 3 is connected with a lever 55 of the clutch 51. Therefore, when operating the clutch pedal 54 in the direction of Arrow C, the inner wire 3 slides within the conduit 2 in the direction of Arrow A so that a clutch plate 57 is separated from a clutch plate 56.

Further, when releasing the operation of the clutch pedal 54, the clutch plate 57 comes in contact with the clutch plate 56 by means of return springs 58 and the clutch pedal 54 is returned to the original position (the direction is indicated by Arrow D in Fig. 4).

Fig. 1 shows the tension regulating device in the state that the clutch pedal 54 is not operated, i.e. the inner wire is pulled in the direction of Arrow B in Fig. 4 and the nipple 43 is urged toward the first associating portion of the lock-releasing member 24. The lock-releasing member 24 is urged in the direction of Arrow B and, therefore, the second associating portion 26 of the flange portion 25 urges the second cam portion 22 of the pawl member 18 outwardly in the radial direction with respect to the axis of the cap member 4 so as to release the engagement between the pawl 20 of pawl member 18 and the male screw portion 8 of the cap member 4. Accordingly, the pawl 20 of the pawl member 18 is disengaged with the male screw portion 8 of the cap member 4 in that state. Therefore, the cap member 4 can freely move within the casing 10 in the axial direction.The tension regulation of the inner wire of the control cable can be performed in such a state.

When the permanent elongation occurs to the inner wire 3, the compression applied to the conduit 2 in the axial direction is reduced.

That is to say, in a control cable arranged in a curved state, a conduit receives a compression from an inner wire being in a tension condition as a reaction force. Then, the cap member 4 is moved in the direction of Arrow B by means of the coil spring 39 so as to apply an appropriate compression to the conduit 2, i.e. to apply an appropriate tension to the inner wire 3. Further, when a shrinkage occurs to the inner wire 3 due to a drop in temperature, or the like, or when the clutch plates 56, 57 are worn out with each other, the clutch plates 56, 57 do not become in contact with each other even if the operation of the clutch pedal 54 is released. In that case, the inner wire 3 goes on receiving an excessive tension from the return spring 58 and, at the same time,the conduit 2 also receives a large compression.

In that case, the cap member 4 is moved in the direction of Arrow A in Fig. 1 against the urging force of the coil spring 39 so that the compression of the conduit 2 and the urging force of the coil spring 39 balances with each other. Accordingly, the length of the conduit 2 becomes short and, therefore, the length of the inner wire 3 disclosed in an atmosphere at the clutch 51 side is made long. As a result, the lever 55 is operated in the direction of Arrow B in Fig. 4 and, the clutch plates 56, 57 are surely engaged with each other without being incompletely engaged with each other or being separated to each other.

As described above, the tension regulation of the inner wire 3 of the control cable 1 is performed just after every operation of the control cable 1, for example, every operation of the clutch pedal 54. That is to say, the length of the conduit 2 of the control cable 1 is adjusted just after every operation of the control cable 1, so that the tension applied to the inner wire 3 is regulated into the most appropriate state.

The pawl members used in the tension regulating device of the present invention are preferably radially arranged with respect to the cap member 4 and the number thereof is preferably 2 to 4. However, the number of the pawl member may be 1 or more than 4.

Further, the means for urging the pawl member inwardly in the radial direction with respect to the cap member 4 is not limited to the above described mechanism comprising the piston 37 and the coil spring 38, but a torsional coil spring can be used.

Further, the engaging projections are not limited to the male screw portion 8 shown in Fig. 1, but a series of annular projections provided at predetermined intervals on an outer peripheral surface of a part of the second end portion can be used.

According to the present invention, when a looseness or an excessive tenseness occurs to the inner wire, the length of the inner wire is automatically regulated relative to the conduit. Further, the cap member can be much surely locked to the casing, and also the locking state can be much surely released, since the pawl of the rotatable pawl member is engaged and disengaged with the screw portion 20 of the cap member. Farticularly, when the locking operation by means of the pawl member is released, the lock-releasing member forcibly moves all the pawl members outwardly in the radial direction, so that the lock-releasing operation is much sured, stabilized and smoothed. Further, the locking operation and the lock-releasing operation are smoothly performed, so that the tension regulation of the inner wire can be surely performed.

Claims (3)

1. A device for automatically regulating a tension applied to an inner wire of a control cable, comprising: (a) the control cable comprisjng a conduit and the inner wire slidably inserted into the conduit; (b) a cap member having an end portion being connected with an end of the conduit, having a hollow extending in the axial direction of the cap member for slidably inserting the inner wire, and having a series of projections on an outer peripheral surface of the other end portion of the cap member; (c) a casing containing the cap member so that the cap member can move within the casing in the axial direction; (d) a first means for urging the cap member toward the conduit side;; (e) at least one pawl member being rotatably supported at one end thereof within the casing, extending inwardly in the radial direction with respect to the cap member and toward the conduit side so that the free end approaches the series of projections, and having a pawl capable of being engaged with the series of projections at or near a free end thereof; (f) a second means for urging the pawl member inwardly in the radial direction; (g) a lock-releasing member being contained within the casing so that the lock-releasing member can slide in the axial direction, having a small opening into which the inner wire is slidably jnserted, having a first associating portion at an end thereof, and having a second associating portion capable of being associated with the pawl member so that the free end leaves the serious of projections; and (h) a nipple being fixed to the inner wire at the position where the inner wire comes out of the lockreleasing member so as to being associated with the first associating portion.

2. The device of Claim 1, wherein further comprising a third means for urging the lockreleasing member in the outward direction of the casing.

3. A device for automatically regulating a tension applied to an inner wire of a control cable as claimed in Claim 1, substantially as herein described with reference to Figures 1-3 of the accompanying drawings.