DE112016001012T5 - Braking device for an axle of an electric vehicle - Google Patents

Abstract

A brake device (100) for an axle (1000) of an electric vehicle is provided. The brake device (100) has a service brake (50) and a parking brake (70). The braking device (100) is characterized in that the parking brake (70) in turn comprises a mechanical device for locking / unlocking (80) an actuating piston (71), wherein the actuating piston (71) is adapted to a common disc brake holder (60). to act.

Description

Technical area

The present invention relates to a brake device for an axle of an electric vehicle.

More particularly, the present invention relates to a brake device of an electric vehicle having an axle equipped with two wheels driven by two independent electric motors, one for each wheel.

Technical background

Incidentally, it should be noted that the teachings of the present invention could also be applied to an axle or a transmission equipped with a single motor.

Electric vehicles of this kind may be, for example, a storage forklift, a stage platform, a towing vehicle, etc.

It is known in the field of electric traction vehicles, such as forklift trucks, that axles are equipped with two independent electric motors, one for each hub and for each driven wheel. Each hub is also equipped with an associated planetary gear.

Axes of this type further include a planetary gear for each wheel, a parking brake unit provided in common for the two driven wheels, and a service brake unit also provided in common for the two driven wheels.

It is known that while the service brake is of the "normally open" or "normally released" type, and therefore must be actuated directly by an operator, typically by hydraulic actuation means, the parking brake is instead of the "normally closed." Or "normally operated" type, and is actuated by hydraulic actuating means or electrical means having a coil.

In other words, the parking brake is always engaged (for safety reasons) until the electric vehicle is started by the operator. That is, when the operator instructs the start of the electric vehicle, an electronic control system generates a signal which, by passing an electric current through the coils, generates an electromagnetic force that moves a piston releasing the parking brake, so that the vehicle moves.

One of the problems resulting from this type of parking brake operation is that, in order to stay in the released position and allow the vehicle to move, the coil must be continuously energized by passing an electrical current; this clearly results in continuous power consumption with consequences for overheating and reduced battery autonomy and thus reduced productivity, especially in the case of heavy duty trucks where very large parking brakes (and related coils) are mounted.

Disclosure of the invention

Therefore, the main object of the present invention is to provide a brake device provided with a parking brake which overcomes the disadvantage described above while being simple and inexpensive to manufacture.

Thus, according to the present invention, there is provided a brake device for an axle of an electric vehicle as claimed in claim 1 or as claimed in any one of claims directly or indirectly dependent on claim 1.

Brief description of the drawings

For a better understanding of the present invention, a preferred embodiment will now be described, purely by way of non-limiting example, with reference to the accompanying drawings, in which:

1 Figure 11 illustrates an exploded view of an axle of an electric vehicle having a brake device according to the teachings of the present invention;

2 shows an enlarged and partially cut part of in 1 illustrated axis;

3 Fig. 11 illustrates a first view of certain details associated with the brake device according to the present invention; and

4 shows a second view of certain details that belong to the braking device according to the present invention.

Best way to carry out the invention

In the 1 and 2 denotes the reference numeral 1000 an axle of an electric vehicle (not illustrated in its entirety); being the axis 1000 a braking device 100 according to the teachings of the present invention.

The axis 1000 has a longitudinal axis (X) to which it is substantially symmetrical.

The brake device 100 again has a service brake 50 and an actuating device for the parking brake 70 on.

Before the brake device 100 it is necessary to briefly describe the other components of the axle 1000 to mention.

In principle, the axis points 1000 two side housings (CRTL) arranged symmetrically with respect to a central housing (CRTC) ( 1 ); wherein each side case (CRTL) contains in its interior a respective (not shown) electric traction motor.

Each side case (CRTL) is coupled by means of a respective flange (FLG) to a respective reduction gear box (not shown), which in turn is connected by known means to a respective wheel (not shown).

Each gear box contains in its interior a respective mechanical gear, for example of the planetary gear type (not illustrated), which is used in a known manner to reduce the number of revolutions output from the respective electric traction motor, and therefore the active torque to increase on the bike.

As in the 1 and 2 As shown, each electric traction motor causes a respective grooved shaft (SHS) projecting toward the center housing (CRTC) to rotate.

In known manner, each splined shaft (SHS) is coupled to a respective rotating disc brake (not illustrated) which carries on its inside teeth coupled to the grooves of the grooved shaft (SHS).

The two rotating disc brakes are in a disc brake holder 60 included in the middle housing (CRTC) for the service brake 50 and the parking brake 70 is shared.

The disc brake holder 60 For example, has three fixed disc brakes that do not move relative to the middle housing (CRTC).

It should be noted that in this case the solid disc brakes must be three in number so that each rotating disc brake is provided between two fixed disc brakes.

Conventionally, springs (not shown) are disposed between the (rotating and stationary) disc brakes, the springs being adapted to return the disc brake holder to the initial configuration once the braking operation (both the service braking operation and the parking brake operation) is over.

One or more approaches 61 (for example, three in 1 to be seen) are the scope of the disc brake holder 60 outwardly to (by known and not illustrated means) the disc brake holder 60 at the middle housing (CRTC).

As again in 1 is shown on the right side of the middle housing (CRTC) the above-mentioned service brake 50 which, as previously mentioned, is of the "normally open" type.

The service brake 50 has a piston in a known manner 51 on (which is substantially axially symmetrical shaped), which is adapted to the brake discs of the brake disc holder 60 to act.

This piston 51 is by an actuator 52 activated, which is for example of the hydraulic type (but which could also be electrical or of a different type).

When the piston 51 by the action of the actuator 52 moves in a parallel manner with respect to the axis (X) in a direction indicated by an arrow (F1), it closes the brake disc holder 60 by pressing the (movable and fixed) discs against each other. In such a way, an indirect braking effect on the two shafts (SH) is achieved, thus providing the desired deceleration of the axle 1000 and therefore the entire electric vehicle is achieved.

The piston 51 moves back as soon as the "positive" signal stops, which is applied as a result of the force of the separating springs and the viscous force generated between the brake discs.

What about the parking brake 70 (of the normally closed type), this has a piston 71 (which is made of a ferromagnetic material and is substantially cylindrically shaped), which normally presses the (movable and fixed) disc holder, so that the discs are pressed against each other, thus what the axis 1000 due to the compressive force of a variety of springs 74 held in the braked state (in this embodiment, the springs of the helical spring type).

When the operator starts the vehicle, a coil pulls 72 (which acts as an electromagnet), which on a flange 73 is mounted, the piston 71 towards itself (in a direction identified by an arrow (F3)), thereby overcoming the elastic resistance produced by the coil springs 74 is exerted with an axis parallel to the axis (X); the coil springs 74 more precisely between the piston 71 and a front end 73A of the flange 73 are arranged, on which the coil 72 is arranged.

Therefore, the coil springs 74 due to the pressure effect of the piston 71 on the front side 73A pressed together.

At this point, the system would need continuous electrical power to the coil 72 Deliver to continue the parking brake 70 to keep it open.

It is obvious that all this would entail a considerable waste of electrical power and a truly considerable waste of power in the case of very large axles which would require particularly powerful brakes with large coils (electromagnets) and the use of considerable electromagnetic forces would bring with it.

To overcome this problem, therefore, is the outer circumferential edge 71A of the piston 71 with a surrounding collar 71B been provided, which projects outward.

The circulating collar 71B has a variety of recesses 71C which are equally spaced apart.

The solution chosen in the present case consists of four recesses 71C each of which is arranged at 90 ° with respect to the two adjacent recesses.

In fact, the number of recesses depends 71C from the requirements of the project and, if necessary, could be a solution with only one recess 71C be used.

The parking brake 70 has a mechanical device around the piston 71 to lock / unlock in the open position 80 ,

The mechanical device for locking / unlocking 80 again has a ring 81 on that with tabs 82 is provided, which protrude inwardly and radially in the direction of the axis (Z).

It should be noted that the number of protrusions 82 on the ring 81 are present, equal to the number of recesses 71C on the above circumferential collar 71B is.

Therefore, if the projections 82 the recesses 71C Precise face is when the magnetic tightening force on the piston 71 through the coil 72 caused, an axial displacement of the piston 71 in the direction of the arrow (F3) possible.

If instead the piston 71 from the discs of the disc brake holder 60 If it is to be kept dissolved, it will be sufficient even in the absence of magnetic force, the ring 81 to rotate about the axis (Z) in a direction indicated by an arrow (F4) so that the projections 82 no longer at the recesses 71C but against a full or unbroken page 71C of the circulating federal government 71B rest to the piston 71 in the of the disc brake holder 60 to hold the dissolved position, the ring 81 again in the axial direction by suitable projections provided on the housing (CRTC) ( 2 ).

The rotation of the ring 81 about the axis (Z) (arrow (F4)) is controlled by an actuator 83 running tangentially on the ring 81 acts.

Advantageously, but not necessarily, is the actuator 83 also of the electrical design.

It should also be noted that the actuator 83 overcomes the elastic resistance of a spring (not shown) and that the mechanism is retained without any waste of electrical power, thanks to the thrust (and friction) provided by the piston 71 on the ring 81 through the coil springs 74 is exercised.

It should also be noted that to increase the safety of the system and to permit manual engagement of the brake system in the absence of electrical power due to a fault, two actuators may be present (see attached figures). All elements are held together by a plurality of screws (SCR), each screwed into a corresponding screw hole (HL).

The next time the parking brake 70 it will be sufficient to send an electrical command to the coil 72 so that after the thrust of the magnetic force no frictional force between the actuator 71 and the ring 81 and thus the force of the spring acting in the actuator 83 there is the ring 81 in a direction indicated by an arrow (F5) opposite to the direction of the arrow (F4).

If at this point every lead 82 right in front of the respective recess 71C lies, the piston becomes 71 again against the discs of the disc brake holder 60 pressed (in the direction shown by an arrow (F6)) due to the thrust generated by the coil springs 74 is exercised, causing the parking brake 70 is created again.

According to the present invention also the possibility of connection of the actuator 83 with a (not shown) wire rope considered, so that in case of failure of the ring 81 Manually rotated from the outside to manually apply the parking brake 70 to solve after the piston 71 has been pushed back following the application of a manual control on the piston 51 the service brake 50 ,

The main advantage of the brake device according to the present invention is that by using a simple mechanical device for locking / unlocking the piston, the amount of electrical power needed to keep the parking brake open is nearly zero.

Claims (8)

Brake device ( 100 ) for one axis ( 1000 ) of an electric vehicle; the braking device ( 100 ) Comprises: - a service brake ( 50 ); and - a parking brake ( 70 ); the service brake ( 50 ) and the parking brake ( 70 ) a common disc brake holder ( 60 ) exhibit; a braking device, characterized in that the parking brake ( 70 ) again a mechanical device for locking / unlocking ( 80 ) of actuating means ( 71 ) having; the actuating means ( 71 ) are adapted to on the common disc brake holder ( 60 ) to act. Brake device ( 100 ) according to claim 1, characterized in that the mechanical locking / unlocking device ( 80 ) of the actuating means ( 71 ) a ring ( 81 ), which with radial projections ( 82 ) provided with corresponding recesses ( 71C ) can be engaged, which at the actuating means ( 71 ) are provided to selectively an axial displacement of the actuating means ( 71 ) to perform the braking operation if necessary. Brake device ( 100 ) according to claim 2, characterized in that the recesses ( 71C ) on a circulating collar ( 71B ) are formed to the outside of the actuating means ( 71 ) protrudes. Brake device ( 100 ) according to claim 2 or claim 3, characterized in that the number of radial projections ( 82 ) equal to the number of recesses ( 71C ). Brake device ( 100 ) according to one of claims 2 to 4, characterized in that the locking / unlocking device ( 80 ) also actuating means ( 83 ) tangent to the ring ( 81 ) act around the ring ( 81 ) about a longitudinal axis (X), which substantially a symmetry axis of the axis ( 1000 ). Brake device ( 100 ) according to claim 5, characterized in that the actuating means ( 83 ) are further connected to manual actuation means which can be activated in case of failure. Axis ( 1000 ) of an electric vehicle, which with at least one braking device ( 100 ) is provided according to claims 1 to 6. Electric vehicle having at least one axle ( 1000 ) according to claim 7.

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