Charging plug connection of a traction battery of a mobile work machine

Abstract

Charging plug connection (19) for a charger and a traction battery (2) of a mobile working machine, in particular a forklift truck, with a battery plug unit (18) of the traction battery (2) and with a charger plug unit (1) arranged on a connecting cable (5) with a hand lever (11) pivotable about a lever axis (25), wherein the hand lever (11) is mounted on the lever axis (25) on the charger plug unit (1), wherein the hand lever (11) has a cam guide (16) for a cam block (20) of the battery plug unit (18), wherein at least one cam track (23, 24) exerts a connecting or separating force on the cam block (20) during a pivoting movement of the hand lever (11), characterized in that the charger plug unit (1) has a retaining element (8) which allows attachment to a heavy object, in particular the traction battery (2) or a building wall,enabled and the charger plug unit (1) has a handle (9).

Description

The present invention relates to a charging plug connection for a charger and a traction battery of a mobile working machine, in particular a forklift truck, comprising a battery plug unit of the traction battery and a charger plug unit arranged on a connecting cable with a hand lever pivotable about a lever axis, wherein the hand lever is mounted on the lever axis on the charger plug unit, wherein the hand lever has a cam guide for a cam block of the battery plug unit, wherein at least one cam track exerts a force on the cam block connecting or separating the plug units during a pivoting movement. Battery-electric powered mobile work machines are well-known, and among these, industrial trucks are particularly common. These machines have a traction battery from which all the vehicle's drive energy is drawn, both for propulsion and for work devices. For example, in a forklift truck, such a work device could be the lifting mechanism of a mast. Traction batteries are conventionally designed as lead-acid batteries, which, due to the power requirements, have large capacities and can weigh up to more than a ton. Newer traction batteries, so-called high-performance batteries, which utilize newer technologies such as lithium-ion cells, offer significantly higher power and energy densities with the same physical size and often lower weight. When the mobile machine or forklift draws the full power provided by the traction battery, relatively high currents flow. The traction battery is typically designed as a replaceable battery, located in a battery compartment of the vehicle and removable for recharging.This allows, for example, in multi-shift operation of industrial trucks, a discharged traction battery to be replaced with a charged one without requiring any work interruption for recharging. For this to work, the traction battery must be connected to the mobile machine via a plug connection. This connection consists of two plug units: a socket and a plug. One plug unit is located on a connection cable of the traction battery, and the second plug unit is connected to the vehicle. Due to the high currents and large power transmissions, the contacts of the connector unit are relatively large and must exhibit high surface pressure to prevent unwanted heating caused by high contact resistance. Therefore, significant actuation forces are required when inserting and removing the connector. To simplify operation, it is therefore common practice to permanently attach one of the two connector units to the vehicle frame, rather than just using a connecting cable. This fixed attachment allows a single person to connect the battery connector system simply by handling the second, or loose, connector unit. The corresponding connector unit of the traction battery typically has a handle that allows it to be connected to the connector unit permanently attached to the vehicle frame by applying the necessary force. To recharge the traction battery, it can be connected to a charger either while installed in the vehicle or removed from the vehicle. For this purpose, a connector unit matching that of the mobile work machine is attached to a connection cable of the charger to create a charging plug connection. A disadvantage of this state of the art, however, is that the operating forces required for large connector units are very high, both when connecting to the mobile work machine and to a charger. Even for a strong person, connecting or disconnecting a permanently attached connector unit is difficult. Furthermore, the locking and securing of the connected battery connector system relies solely on the spring force of the connector units' contacts. In addition, in the case of a charging connector connection, the traction battery connector unit is attached to a connecting cable, and the charger connector unit is also typically attached to a connecting cable to allow for flexible connection options with the traction battery.As a result, a charging plug connection often lacks a firm support for one plug unit to allow the necessary connection or disconnection forces to be applied with both hands using the second plug unit. From the subsequently published DE 10 2014 101 469 A1 and the subsequently published DE 10 2014 118 140 A1, a charging plug connection with the features of the preamble of claim 1 is known. US 3 836 938 A discloses a lever-operated safety connection and disconnection mechanism for a pair of electrical cable connections. From JP H-06 215828 A, a battery connector system with an insertion and disconnection aid is known, consisting of a lever on which the loose connector unit is attached in the area between a lever axis and a lever end serving as a handle. The loose connector unit is attached to the same lever arm as the handle, on the same side opposite the lever axis. A disadvantage of this state of the art is that it requires a relatively large amount of space, since the lever axis has to be located to the side of the loose plug unit and the lever arm has to be relatively long overall for sufficient leverage. The present invention therefore aims to provide a charging plug connection for a mobile work machine that avoids the aforementioned disadvantages and with which a plug connection as a charging plug connection with a charger can be established with low actuating forces. This problem is solved by a charging plug connection with the features of independent claim 1. Advantageous embodiments of the invention are specified in the dependent claims. The object of the invention is achieved by providing a charging plug connection for a charger and a traction battery of a mobile work machine, in particular a forklift truck, comprising a battery plug unit of the traction battery and a charger plug unit arranged on a connecting cable with a hand lever pivotable about a lever axis, wherein the hand lever is mounted on the lever axis on the charger plug unit, wherein the hand lever has a cam guide for a cam block of the battery plug unit, wherein at least one cam track exerts a force connecting or separating the plug units on the cam block during a pivoting movement of the hand lever, the charger plug unit has a retaining element that enables attachment to a heavy object, in particular the traction battery or a building wall, and the charger plug unit has a handle. Advantageously, the lever arm of the hand lever and the cam guide can be used to apply a force to push or separate the battery connector unit from the charger connector unit. Depending on the design, either a pushing or separating force, or both, are possible. This auxiliary mechanism significantly improves ergonomics, as the battery connector unit only needs to be positioned, and a subsequent pivoting motion of the hand lever connects the battery connector system. The risk of injury during insertion or removal is reduced because slippage cannot occur when significant force is applied to the connector unit, and easy operation by a single person is possible. The cam block on the loose connector unit is typically a round bolt.The charger connector unit should preferably be secured against a support point, for example by a clamp or holding device. Suitable support points include a building component such as a wall, the traction battery (due to its considerable weight), or even a forklift. According to the invention, the charger plug unit has a retaining element that enables it to be attached to a heavy object, in particular a traction battery or a building wall. By attaching the charging plug to a heavy object, such as the forklift, the traction battery, or even a building element, the operating forces can be supported, preventing the charging plug connection from slipping when the hand lever is operated. The traction battery itself is particularly suitable for this purpose, as conventional designs typically feature a battery tray with an upper edge to which, for example, the retaining element can be attached with suitable connecting elements. Alternatively, with a fixed charging station, it is also conceivable to screw the charging plug unit to a wall, for instance. According to the invention, the charger plug unit has a handle. This allows for easier handling of the charger plug unit and placement, for example, on the top edge of the battery tray. Advantageously, the cam track can, at least over part of its length, effect a force transmission by means of a gradient in relation to a line running to the lever axis during a pivoting movement of the hand lever. When the hand lever is moved, a force acts on the cam follower via a surface lying in a straight line with the lever axis. This force depends solely on the lever arm on this straight line relative to the lever axis and acts in a direction perpendicular to this surface. However, if the cam follower track has a slope relative to this straight line, the direction of the exerted force can be controlled. For example, a larger component can be applied in the direction of movement to connect to the optimal plug unit. Furthermore, a significant increase in force can be achieved by the cam follower sliding along the slope. In a training course, the slope changes with the distance to the lever axis. As the cam block slides along the cam track, its distance from the lever axis changes. For example, a suitably adapted curve can achieve a uniform or essentially constant force throughout the entire process of pushing the plug units together. Any other control of the force via this movement is also possible. For example, a greater force can be applied at the beginning of the pushing process. The cam block can be guided in a linear guide that is fixed opposite and aligned with the charger plug unit, while at the same time the cam track acts on the cam block. For example, contact pins inserted into sockets provide a degree of guidance after the loose connector unit is attached to the fixed connector unit. Nevertheless, jamming can still occur. Therefore, it is advantageous if the battery connector unit is also guided in the correct direction of movement by the cam tracks. Furthermore, by simultaneously engaging the cam track of the hand lever and the guide on the same cam track, a force component that does not point towards or away from the fixed connector unit can be supported. This forced guidance advantageously protects the battery connector system and both connector units from mechanical stress. In another embodiment, the guide is a slot in a sheet of metal. The hand lever can have cam tracks for connecting and disconnecting the charging plug connection. This allows the battery connector system to be operated with minimal effort, both when connecting and disconnecting. In particular, it is also possible to design the force curve differently for connecting and disconnecting by using different characteristic curves for the cam tracks. In an advantageous embodiment of the charging plug connection, the retaining element allows it to be hooked onto the upper edge of a battery tray of a traction battery via an angled strip. The upward-projecting edge of the battery tray is particularly suitable for mounting using a retaining element. This can be a simple hook, or a design with a slot for the top edge of the battery tray. It is conceivable that longitudinal movement along the battery tray can be prevented, for example, by securing the retaining element in a corner of the tray at a 90° angle to each other. Alternatively, clamping elements or spring elements can be used to fix the retaining element to the top edge of the battery tray, or a separate clamping mechanism can be employed. A return spring can push the hand lever into a position where the hand lever rests against the charger plug unit. In particular, this ensures that the hand lever is returned to its starting position when the charging plug connection is not actuated or not locked, thus preventing the hand lever from being unintentionally raised during transport of the charger plug unit. The charger plug unit advantageously has a U-shaped profile, in the space between which plug contacts are arranged, with a hand lever arranged on each side wall and the two hand levers being connected at their lever end by a handle. The lever axes can be arranged directly adjacent to the base of the U-shaped profile. The guides, as previously described, can be arranged above the lever axes in relation to the bottom of the U-shaped profile. Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiments shown in the schematic figures. Fig. 1 shows a charger plug unit according to the invention attached to a traction battery, Fig. 2 shows the charger plug unit with the traction battery of Fig. 1 in a front view, Fig. 3 shows the charger plug unit of Fig. 1 with the hand lever open, Fig. 4 shows the charger plug unit of Fig. 1 with the hand lever open and a battery plug unit of the traction battery forming a charging plug connection, Fig. 5 shows the charger plug unit of Fig. 4 with the battery plug unit attached, Fig. 6 shows the charging plug connection of Figs. 4 and 5 in the locked state, Fig. 7 shows the charging plug connection of Fig. 4 schematically in a top view when locked, and Fig. 8 shows the charging plug connection of Fig. 4 schematically in a top view when unlocked. Fig. 1 shows a charger connector unit 1 according to the invention attached to a traction battery 2 with a battery tray 3 and battery cell terminals 4. The charger connector unit 1, connected by a connecting cable 5, consists of connection sockets 6 arranged in a U-shaped profile 7. The U-shaped profile 7 is connected to a retaining element 8, on which a handle 9 is mounted. A hand lever 11 is arranged on each side wall 10 of the U-shaped profile 7. Each of the hand levers 11 is connected to the other on the opposite side of the U-shaped profile 7 via a handle 12. The charger connector unit 1 is mounted onto an upper edge 13 of the battery tray 3 by means of the retaining element 8. Fig. 2 shows the charger connector unit 1 with the traction battery 2 of Fig. 1 in a front view. The charger connector unit 1 is placed on the upper edge 13 of the battery tray 3 via the retaining element 8 with the handle 9, where it is held by an angle bracket 14. The hand levers 11, arranged within the U-shaped profile 7 and connected by the handle 12, are pushed back into the locked position by a return spring 15 when the charger connector unit 1 is not connected to a battery connector unit. The connection sockets 6 are also located within the U-shaped profile 7. Fig. 3 shows the charger connector unit 1 of Fig. 1 with the hand levers 11 open in a perspective view from the front. The charger connector unit 1 is placed on the upper edge 13 of the battery tray 3 of the traction battery 2 via the retaining element 8 with the handle 9 and the angle bracket 14. A cam guide 16 integrated into the hand levers 11, together with guides 17, forms openings into which cam blocks of a battery connector unit can be inserted. Fig. 4 shows the charger connector unit 1 of Fig. 1 with the hand lever 11 open and a battery connector unit 18 of the traction battery 2, forming a charging connector connection 19. The battery connector unit 18 has locking blocks 20 and a handle 22. In the illustration of Fig. 4, the battery connector unit 18 is aligned with the charger connector unit 1, which is placed on the upper edge 13 of the battery tray 3. Fig. 5 shows the charger plug unit 1 of Fig. 4, which is placed on the upper edge 13 of the battery tray 3 via the retaining element 8, with the battery plug unit 18 attached. The cam blocks, which are not visible here, are then inserted into the cam guides 16 and guides 17 of Fig. 3, since the hand levers 11 are fully open. Fig. 6 shows the charging plug connection 19 of Figs. 4 and 5 in the locked position. The battery plug unit 18 is drawn into the locked position against the charger plug unit 1 via the hand levers 11 and the guide of the cam blocks in the cam guides 16 (not visible here). Fig. 7 shows a schematic top view of the charging plug connection 19 from Fig. 4, shown in the locked position and arranged on the battery tray 3. The pivoting movement of the hand lever 11, as indicated by the arrow, presses the battery plug unit 18 onto the charger plug unit 1 in the direction of the second arrow. This is achieved by a cam track 23 arranged on the hand lever 11 as part of the cam guide 16, which exerts a corresponding force on the cam blocks 20, a force reduced by the leverage of the hand lever 11. Force components that do not act directly towards the charger plug unit 1 are supported by the guide 17, which consists of a slot in the U-shaped profile. The hand lever 11 is mounted on a lever axis 25 on the charger plug unit 1.Since the battery connector unit 18 has cam blocks 20 on both sides and hand levers 11 with a cam track 23 are arranged on both sides, the battery connector unit 18 is pressed onto the charger connector unit 1 with a force on both sides and cannot become jammed. Fig. 8 shows a schematic top view of the charging plug connection 19 of Fig. 4 during unlocking. By pivoting the hand lever 11 in the opposite direction to Fig. 7, as indicated by the arrow, the battery plug unit 18 is pushed away from the charger plug unit 1 in the direction of the second arrow. This is achieved by a second cam track 24 arranged on the hand lever 11 as part of the cam guide 16, which exerts a corresponding force on the cam blocks 20, a force reduced by the leverage of the hand lever 11. Force components that do not act directly towards the charger plug unit 1 are supported by the guide 17, which consists of a slot in the U-shaped profile.

Claims

Charging plug connection (19) for a charger and a traction battery (2) of a mobile working machine, in particular a forklift truck, with a battery plug unit (18) of the traction battery (2) and with a charger plug unit (1) arranged on a connecting cable (5) with a hand lever (11) pivotable about a lever axis (25), wherein the hand lever (11) is mounted on the lever axis (25) on the charger plug unit (1), wherein the hand lever (11) has a cam guide (16) for a cam block (20) of the battery plug unit (18), wherein at least one cam track (23, 24) exerts a connecting or separating force on the cam block (20) during a pivoting movement of the hand lever (11), characterized in that the charger plug unit (1) has a retaining element (8) which allows attachment to a heavy object, in particular the traction battery (2) or a building wall,enabled and the charger plug unit (1) has a handle (9). Charging plug connection (19) according to claim 1, characterized in that the cam track (23, 24) at least over part of its length, by means of a gradient in relation to a line running to the lever axis (25), effects a force transmission during a pivoting movement of the hand lever (11). Charging plug connection (19) according to claim 2, characterized in that the slope changes with the distance to the lever axis (25). Charging plug connection (19) according to one of claims 1 to 3, characterized in that the cam block (20) can be guided in a linear guide (17) fixedly arranged opposite and aligned with the charger plug unit (1), while at the same time the cam track (23,24) acts on the cam block (20). Charging plug connection (19) according to claim 4, characterized in that the guide (17) is a slot in a sheet metal part. Charging plug connection (19) according to one of claims 1 to 5, characterized in that the hand lever (11) has cam tracks (23, 24) for connecting and disconnecting the charging plug connection (19). Charging plug connection (19) according to one of claims 1 to 6, characterized in that the retaining element (8) enables hooking onto the upper edge (13) of a battery tray (3) of a traction battery (2) via an angle strip (14). Charging plug connection (19) according to one of claims 1 to 7, characterized in that a return spring (15) pushes the hand lever (11) into a position in which the hand lever (11) rests against the charger plug unit (1). Charging plug connection (19) according to one of claims 1 to 8, characterized in that the charger plug unit (1) has a U-shaped profile (7) in the space between which plug contacts are arranged, wherein a hand lever (11) is arranged on each side wall and the two hand levers (11) are connected at their lever end by a handle (12). Charging plug connection (19) according to claim 9, characterized in that the lever axes (25) are arranged directly adjacent to the bottom of the U-shaped profile (7). Charging plug connection (19) according to claim 10, characterized in that guides (17) according to one of claims 4 or 5 are arranged above the lever axes (25) with respect to the bottom of the U-shaped profile (7).

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