Technical Field The present disclosure generally relates to an electric connector assembly. In particular, an electric connector assembly comprising an electric harness, a connector and a backshell, and an industrial actuator comprising an electric connector assembly, are provided.

Background Some prior art electric connector assemblies for dynamic applications comprise a harness and a molded backshell that fixes electric conductors statically. Since the conductors are fixed, the conductors are subjected to stress when the harness moves. The conductors thereby risk being damaged. Such prior art electric connector assemblies do therefore not work satisfactorily in dynamic applications.

WO 0007196 A2 discloses a connector for connecting a plurality of cables. The connector comprises a backshell having a plurality of passages and a plurality of cables. Each cable passes through a respective passage in the backshell. Each cable carries an outer shielding layer. The shielding layer is connected to the backshell at the passages.

Summary

One object of the present disclosure is to provide an electric connector assembly that enables a reliable performance for dynamic applications.

A further object of the present disclosure is to provide an electric connector assembly that reduces a risk of damage of one or more electric conductors when a harness moves. A still further object of the present disclosure is to provide an electric connector assembly that has a simple and/or cost-effective design.

A still further object of the present disclosure is to provide an electric connector assembly that enables simple and/or cost-effective manufacture. A still further object of the present disclosure is to provide an electric connector assembly that solves several or all of the foregoing objects in combination.

A still further object of the present disclosure is to provide an industrial actuator comprising an electric connector assembly, which industrial actuator solves one, several or all of the foregoing objects.

According to one aspect, there is provided an electric connector assembly comprising a connector; an electric harness having at least one electric conductor and a protective layer surrounding the at least one conductor, the at least one conductor being connected to the connector; and a backshell connected to the protective layer and to the connector, the backshell comprising a cavity between the protective layer and the connector; wherein the at least one conductor is arranged to move freely inside the cavity when the harness moves relative to the connector.

In comparison with prior art connection assemblies where the conductors are stressed, where the backshell is molded over the conductors to lock the conductors, or where the conductors are fixed in some other way, the electric connector assembly according to this aspect comprises one or more conductors that are freely movable within a cavity inside a backshell. The one or more conductors are allowed to move, such as bend and/or twist, inside the cavity as the harness moves relative to the connector. The conductors may be allowed to move independently inside the cavity. The free movements of the at least one conductor inside the cavity greatly reduces the risk of breakage or damage of the at least one conductor. The free movement may for example be defined as each conductor comprising a point that can move a distance of at least 5 %, such as at least 10 %, of a distance between the protective layer and the connector when the harness moves relative to the connector.

The electric connector assembly is particularly suitable for dynamic applications. In such dynamic applications, various types of relative movements between the harness and the connector typically occur.

The protective layer may end inside the cavity such that the at least one conductor is exposed. The at least one conductor may be exposed along a major length inside the cavity, e.g. when the harness is aligned with the connector. The at least one conductor may extend freely all the way from the protective layer to the connector. The cavity may extend all the way from the protective layer to the connector.

The connector may comprise one or more pins, each pin being electrically connected to a unique conductor. Each conductor may be secured to the connector. The connector may be of a wide range of types. Each conductor may be an individual conductor wire.

The backshell may be flexible. In this case, the backshell may flex as the harness moves relative to the connector. The backshell may for example allow bending and/or twisting of the backshell. The stiffness of the flexible backshell may be such that it can be bent by hand. When the backshell is straight, the harness is aligned with the connector. The straight state of the backshell may or may not be the neutral state of the backshell.

As an alternative, the backshell may be rigid. The stiffness of the rigid backshell maybe such that it can not be bent by hand. Also for a rigid backshell, relative movements between the harness and the connector may cause the one or more conductors to move inside the cavity. The harness may for example be bent or twisted by torsion relative to the connector.

In any case, the backshell may be substantially inelastic. In this way, the backshell can resist pulling forces on the harness without stressing the one or more conductors. The at least one conductor may comprise a slack of at least 3 %, such as at least 5 % in a state where the harness is aligned with the connector. The slack further contributes to avoiding stressing the one or more conductors.

A width of the cavity may be at least 20 %, such as at least 40 %, of a length of the cavity between the protective layer and the connector when the harness is aligned with the connector. A width direction is a lateral direction with respect to a central axis of the electric connector assembly when the harness is aligned with the connector.

The at least one conductor may be arranged to move laterally inside the cavity. The degree of lateral movement depends inter alia on the slack of the one or more conductors and on the lateral play within the cavity.

The at least one conductor may comprise a plurality of conductors. In this case, each conductor may be arranged to move independently with respect to the one or more other conductors.

The backshell may be configured to be bent at least 45 degrees, such as at least 90 degrees, from a state where the harness is aligned with the connector. For example, the backshell maybe configured to be bent at least 45 degrees, such as at least 90 degrees, from a state where the harness is aligned with the connector, while the at least one conductor is free between the protective layer and the connector. That is, while the at least one conductor is separated from the backshell, or from a sheet on the inside of the backshell, as the case may be.

The harness may have a torsion range of at least ± 90 degrees per meter, such as at least ± 170 degrees per meter. That is, the harness can be rotated 90 degrees in each direction from a neutral state without stressing the one or more conductors.

The backshell may be configured to be twisted at least 15 degrees in each direction about a central axis of the electric connector assembly. That is, a part of the backshell connected to the protective layer may be rotated at least 15 degrees in each direction about the central axis relative to a part of the backshell connected to the connector.

The backshell may be molded. This reduces costs of the backshell, for example in comparison with an electric connector assembly comprising a gland. The backshell may be molded onto the connector to thereby fix the backshell to the connector. Alternatively, or in addition, the backshell may be molded onto the protective layer to thereby fix the backshell to the protective layer. In these ways, the manufacturing process of the electric connector assembly is facilitated. The backshell may sealingly close the cavity. The backshell may be configured to protect the at least one conductor from various environmental issues, such as oil, detergent, water, humidity and/or high temperatures. According to one variant, the backshell meets the IEC (International Electrotechnical Commission) 60529 standard IP67. The electric connector assembly may further comprise an electrically conductive sheet on an interior side of the backshell. The sheet ensures that the at least one conductor is separated from the backshell. In case the backshell is molded, the sheet protects the at least one conductor from the molded backshell. The sheet may be formed by a wound tape. The sheet may provide a 360 degrees electric shield. Also the harness may comprise an electric shield.

The electric connector assembly may further comprise a strain relief connecting the backshell to the protective layer. By means of the strain relief, the one or more conductors are further protected from mechanical stress. According to a further aspect, there is provided an industrial actuator comprising an electric connector assembly according to the present disclosure. The industrial actuator may be an industrial robot. Alternative examples of industrial actuators according to the present disclosure are conveyors, positioners, such as workpiece positioners, and track motion platforms. Brief Description of the Drawings

Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein: Fig. l: schematically represents a side view of an industrial robot comprising an electric connector assembly;

Fig. 2: schematically represents a perspective view of the electric connector assembly in a bent state;

Fig. 3: schematically represents a cross-sectional side view of the electric connector assembly in the bent state;

Fig. 4: schematically represents a side view of the electric connector assembly in a straight state; and Fig. 5: schematically represents a side view of the electric connector assembly in a bent state. Detailed Description

In the following, an electric connector assembly comprising an electric harness, a connector and a backshell, and an industrial actuator comprising an electric connector assembly, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.

Fig. 1 schematically represents a side view of an industrial robot 10. The industrial robot 10 is one example of an industrial actuator. The industrial robot 10 of this specific example comprises a base 12, a first link 14a rotatable relative to the base 12 at a first joint, a second link 14b rotatable relative to the first link 14a at a second joint, a third link 14c rotatable relative to the second link 14b at a third joint, a fourth link i4d rotatable relative to the third link 14c at a fourth joint, a fifth link 14e rotatable relative to the fourth link i4d at a fifth joint, a sixth link i4f rotatable relative to the fifth link 14e at a sixth joint, and an end effector 16 connected to the sixth link 14 The industrial robot 10 of this example thus comprises six degrees of freedom. The industrial robot io comprises a plurality of electric motors for driving the joints. Fig. l shows an electric motor 18 of the industrial robot io for driving the fourth joint.

The industrial robot io further comprises an electric connector assembly 20. The electric connector assembly 20 comprises an electric harness 22 containing electric conductors. The conductors transmit power and drive signals to the electric motor 18, in this example from the base 12.

During operation of the industrial robot 10, the electric motor 18 moves relative to the base 12. The electric motor 18 can be moved to a wide range of positions and orientations relative to the base 12.

Fig. 2 schematically represents a perspective view of the electric connector assembly 20 in a bent state. In addition to the harness 22, the electric connector assembly 20 further comprises a connector 24 and a backshell 26. The backshell 26 is molded. The harness 22 comprises a plurality of electric conductors 28, eight in this specific example. The harness 22 further comprises a protective layer 30 surrounding the conductors 28.

A front end of the backshell 26 is rigidly connected to the connector 24 by being molded onto the connector 24. A rear end of the backshell 26 is rigidly connected to the protective layer 30 by being molded onto the protective layer 30. In this example, the electric connector assembly 20 further comprises a strain relief 32. The backshell 26 is rigidly connected to the protective layer 30 by means of the strain relief 32.

The connector 24 comprises a plurality of pins 34. Each pin 34 is electrically connected a unique conductor 28. The connector 24 can be plugged into a socket of the electric motor 18.

The backshell 26 of this example is flexible. As shown in Fig. 2, the backshell 26 is bent approximately 90 degrees. The backshell 26 flexes as the harness 22 moves relative to the connector 24. Fig. 3 schematically represents a cross-sectional side view of the electric connector assembly 20 in the same bent state as in Fig. 2. In Fig. 3, the connector 24 is horizontal and the harness 22 is vertical.

The backshell 26 is hollow and comprises a cavity 36. The protective layer 30 extends slightly into the cavity 36. The individual conductors 28 extend over a main length of the cavity 36. The exposed conductors 28 extend all the way from the end of the protective layer 30 to the connector 24. The cavity 36 extends from slightly behind (below in Fig. 3) the protective layer 30 to the connector 24. As shown in Fig. 3, the conductors 28 are embodied as wires. Each conductor 28 is electrically and mechanically connected to a connector block 38 of the connector 24.

The electric connector assembly 20 further comprises an electrically conductive sheet 40. The sheet 40 is provided on an interior side of the backshell 26 and surrounds the conductors 28. The sheet 40 both functions as an electric shield and prevents the conductors 28 from coming into contact with the molded backshell 26. The sheet 40 is electrically connected to a shield (not shown) of the harness 22.

Each conductor 28 comprises a slack of approximately 5 % when the backshell 26 is in a straight state. Moreover, a width of the cavity 36 is approximately 50 % of a length of the cavity 36 between the protective layer 30 and the connector 24 when the backshell 26 is in the straight state. This enables the individual conductors 28 to move freely within the cavity 36 when the backshell 26 is bent and twisted. Any movements of the harness 22 relative to the connector 24 are absorbed by the backshell 26 without forces from these movements being transmitted to the conductors 28.

As shown in Fig. 3, even though the backshell 26 is bent 90 degrees, there is a lateral play between the conductors 28 and the backshell 26. Thus, none of the conductors 28 is stressed even when the backshell 26 is bent 90 degrees. The electric connector assembly 20 can resist mechanical stress, flexing and torsion without stressing the conductors 28. This enables a reliable function of the conductors 28. The electric connector assembly 20 is therefore very suitable for dynamic applications, such as for the industrial robot 10 where the electric motor 18 may move relative to the base 12 in a repetitive manner over a high number of cycles.

The electric connector assembly 20 may be produced by winding an electrically conductive tape to form the sheet 40 between the protective layer 30 and the connector 24. The backshell 26 can then be molded over the sheet 40 and onto the protective layer 30 and the connector 24. As an alternative, the sheet 40 may be molded before molding the backshell 26 over the sheet 40. In any case, the sheet 40 protects the conductors 28 from the backshell 26 and provides an electric shield.

The IP67 standard as defined in international standard IEC 60529 is an ingress protection rating that defines requirements regarding protection against factors such as dust and liquids. The backshell 26 may provide protection according to IP67. The backshell 26 is thereby protected from total dust ingress and liquid immersion up to 1 m in depth.

Fig. 4 schematically represents a side view of the electric connector assembly 20 in a straight state. In Fig. 4, the backshell 26 is partly open to show the conductors 28 inside. The backshell 26 however sealingly closes the cavity 36.

In the straight state, the harness 22 is aligned with the connector 24 along a central axis 42. Thus, each of the connector 24, the backshell 26 and the harness 22 is concentric with respect to the central axis 42. If the harness 22 is pulled, the pulling force is taken up by the backshell 26 without stressing the conductors 28.

The backshell 26 of this example is straight in its neutral state. Thus, the backshell 26 provides resistance against deformation from the neutral state. The backshell 26 may however alternatively be bent in the neutral state. Due to the slack of the conductors 28 and the lateral play inside the cavity 36, the backshell 26 can be twisted from the straight state, i.e. twisted about the central axis 42, without stressing the conductors 28. The backshell 26 may for example be twisted 15 degrees around the central axis 42 from the neutral state in each direction.

Fig. 5 schematically represents a side view of the electric connector assembly 20 in a bent state. The conductors 28 move independently within the cavity 36 when the backshell 26 is bent from the straight state in Fig. 4 to the bent state in Fig. 5. The conductors 28 move independently and relative to each other when the backshell 26 is bent from the straight state in Fig. 4 to the bent state in Fig. 5.

In case a rigid backshell is employed, the rigid backshell may have the same shape as the flexible backshell 26 in Fig. 4. When the harness 22 moves relative to the rigid backshell, the conductors 28 move freely inside the cavity 36.

While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts maybe varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.