Mobile Storage Unit With Holding Brake And Single Status Line For Load And Drive Detection

Abstract

The present invention is a mobile storage unit including an electric motor operably connected to wheels movably supporting the unit, and a motor brake operably connected to the electric motor. A shaft is rotatably mounted to the unit and supports the wheels on which the unit moves, and is engaged with an electric motor. The electric motor operates to rotate the shaft and the wheels to move the unit in the desired direction. Upon deactivation of the motor, the motor brake, which is also engaged with the shaft, operates to prevent any further rotation of the shaft to maintain the mobile storage unit in a specified location regardless of deflection of the surface on which the storage unit is positioned.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures illustrate the best mode currently contemplated for practicing the present invention.

In the drawings:

FIG. 1 is an isometric view of a mobile storage unit system incorporating the motor brake and single status line of the present invention;

FIG. 2 is a schematic view of the mobile storage system of FIG. 1 and a control arrangement incorporated in the mobile storage system;

FIG. 3 is an enlarged partial section view taken along line 3-3 of FIG. 1;

FIG. 4 is a partial section view taken along line 4-4 of FIG. 3; and

FIG. 5 is a schematic circuit diagram of the main control board and the motor brake and status board shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

With reference now to the drawing figures in which like reference numerals designate like parts throughout the disclosure, a mobile storage system is indicated generally at 10 in FIG. 1. The storage system 10 is mounted over a floor or other supporting surface 11, and includes a pair of end panels or members 12 between which extend a pair of rails 14, in a manner as is known. The rails 14 support a number of storage units 16, each of which is movable on the rails 14 via one or more wheels 18 rotatably mounted to the storage unit 16. Representatively, each wheel 18 may include a pair of flanges 19 between which rail 14 is received, to guide movement of the storage unit on the rail 14. The particular manner in which the wheels 18 are engaged with the rails 14 is known in the art.

Each set of wheels 18 on each storage unit 16 is interconnected by a transverse shaft 20, so that the wheels 18 rotate together. One of the shafts 20 is operably connected to an electric motor 22, which may be secured to a cross member 23 forming a part of the carriage of the storage unit 16. The cross member 23 may be in the form of an inverted channel member, and preferably serves to mount the wheels 18 to the carriage of storage unit 16.

As shown in FIGS. 3 and 4, mounting bracket 27 is secured to one of the vertical walls of cross member 23. Mounting bracket 27 has an inverted L-shape, and a pair of spaced apart openings are formed in the upper horizontal wall of mounting bracket 27. A motor bracket 28 is operable to mount motor 22 to mounting bracket 27. Motor bracket 28 also has an inverted L-shape, and includes an upper horizontal wall that overlaps the upper horizontal wall of mounting bracket 27. Motor 22 is secured to the vertical wall of motor bracket 28, and is oriented horizontally such that the output shaft of motor 22 extends through an opening in the vertical wall of motor bracket 28. The upper horizontal wall of motor bracket 28 includes a pair of slots, which are configured to overlie the openings in the upper horizontal wall of mounting bracket 27. A pair of fasteners F extend through the aligned openings and slots, and are employed to selectively fix motor bracket 28 to mounting bracket 27, and to thereby fix the position of motor 22.

The output shaft of motor 22 drives rotation of a drive gear 35, which in turn is engaged with a driven gear 37 mounted to an axle 39, to which shaft 20 is secured. Wheel 18 is secured to axle 39, such that operation of motor 22 results in driving rotation of wheel 18 through drive gear 35, driven gear 37 and axle 39. In this manner, the motor 22 drives one of the wheels 18 into rotation, which is transferred by shaft 20 to the other wheel 18 in the set of wheels. The other set of wheels 18 rotate synchronously with rotation of the driven wheels 18, to move the storage unit 16 in a desired direction on the rails 14.

It is also understood that the output shaft of motor 22 may be drivingly engaged with a drive shaft interconnected with wheels 18 in any other satisfactory manner, e.g. through a belt or chain drive arrangement, in a manner as is known. The motor output shaft is representatively illustrated at 25, and is rotatable in response to operation of motor 22 to provide rotary output power. The motor 22 is operated in response to actuation through an operator control panel 24 disposed on the storage unit 16, in order to move the particular storage unit 16 along the rails 14 to a desired position. When the motor 22 is not in use to rotate the output shaft 25, the output shaft 25 is free to rotate within the motor 22 and the drive shaft 20 is thus free to rotate along with wheels 18.

It is understood that the drive system as shown and described represents one embodiment of a satisfactory drive system that may be used to impart movement to storage units 16. Many other types of drive systems are known in the art, and may be used to move storage units 16 on rails 14. The present invention is not limited to the specific type of drive system used to move storage units 16 in response to operation of motor 22.

FIG. 2 illustrates deflection of the surface 11 to which the rails 14 are mounted, under the weight of the loaded storage units 16. The deflection of the surface 11 is shown with reference to the dotted line in FIG. 2, which illustrates a normal flat, planar orientation and attitude of surface 11. Surface 11 deflects under the weight of the storage units 16 to a deflected position, shown at 30. Due to the deflection of the surface 26 and correspondingly of the rails 14 mounted to the surface 26, each storage unit 16 tends to drift or move toward the lowermost point 31 of the deflected surface 30, each storage unit 16 tends to move or drift toward the lowermost deflected point 31 under the force of gravity, when motor 22 is not being operated to move the storage unit 16 on the rails 14. Such movement or drifting of the storage unit 16 is caused by rotation of the wheels 18 on the rails 14 and the ability of the drive shaft 20 to rotate relative to the motor 22 when motor 22 is not being operated.

In accordance with the present invention, to prevent the inadvertent movement or drifting of each storage unit 16 along the rails 14 to the lowermost point 31 of the deflected rails 14, the electric motor 22 is also operably connected to a motor brake 32. The brake 32 is mounted to the motor 22 generally at the end of motor 22 opposite the motor bracket 28, and is engaged with the motor output shaft 25. In the illustrated embodiment, the motor brake 32 includes a recess 33 into which the end of motor output shaft 25 extends. Alternatively, the motor brake 32 may be positioned so as to act on the drive shaft 20 or the axle 39. The motor brake 32 may be any satisfactory shaft brake, and representatively may be a Power Off type brake such as is available from Inertia Dynamics of Torrington, Connecticut under its model number 1702-2521. It is understood, however, that any other type of satisfactory shaft brake may be employed.

Referring to FIG. 2, in order to enable the motor 20 and motor brake 32 to be operated in concert with one another, the motor brake 32 is connected via suitable connectors or wires 34 and 38 to a motor brake and status board 36, which can send control signals to operate the brake 32 and also receive an electronic indication of the status of the brake 32. The status board 36 is also operably connected to a main control board 40, from which control signals for the operation of the motor 22 can be sent to the motor 22 in response to user operation of the control panel 24 on the storage unit 16.

In operation, when an individual utilizes the control panel 24 to move a specific storage unit 16, the control board 40 of the specified storage unit 16 sends a signal to the electric motor 22, and to the status board 36 connected to the motor brake 32. This signal, which can be a power signal, causes the electric motor 22 to operate and cause the rotation of the axle 39 and shaft 20 to move the unit 16 in a specified direction. Simultaneously, a signal, such as power signal, is sent to the motor brake 32 from the status board 36 in order to disengage the brake 32 from the shaft 20 through the various drive components, or maintain the brake 32 in a disengaged position, such that the shaft 20 is free to rotate in conjunction with the electric motor 22. Once the unit 16 is positioned where desired, the operator depresses or releases a stop switch (not shown) on the control panel 24. This generates a stop signal that is sent from the control panel 24 to the control board 40, which in turn sends terminates the power signal to the motor 22 to cease operation of the motor 22. Simultaneously, the power signal sent from the control board 40 through the motor brake and status board 36 to the motor brake 32 is terminated, causing the brake 32 to engage the motor shaft 25, and the shaft 20 through the various drive components, and prevent any further rotation of the shaft 20, for maintaining the unit 16 at the specified location.

Looking now at FIG. 5, a circuit diagram of the main control board 40, the motor brake and status board 36, the motor brake 32, and the connections between them is illustrated. There is a multi-wire connection (not shown) between the main control board 40 and the motor brake and status board 36, but only a single wire forms the single status line 42 functions to enable signals from the status board 36 concerning the connection of the status board 36 to the main board 40, and of the connection of the board 36 to a load, via the brake 32. The connection between the motor and brake status board 36 and the motor brake 32 is formed with a pair of wires 34 and 38. These wires 34 and 38 provide the source and the return signals from the status board 36 to control the operation of the brake 32 that enables the holding brake 32 and status board 36 to prevent the storage unit 16 from drifting along the rails 14.

The main control board 40 includes a digital or analog input 44 that is pulled-up to 5V through a resistor 46. Both the input 44 and the resistor 46 are located on the main control board 40 that is connected to the motor brake and status board 36 through the single status line 42. On the motor brake and status board 36, an output 50 of a high side drive 52 is connected to a resistor-ladder 54 including resistors 56, 58 and 60, as well as to the motor brake sourcing output 62. The resistor ladder 54 scales the voltage coming from the high side drive 52 to the positive input 64 of an op-amp 66. A second resistor ladder 68 includes resistors 70 and 72 and provides the switching threshold for the op-amp 66. A resistor divider 74, including resistors 76 and 78, scales the voltage out of the op-amp 66 to be a “high” (3.5V-5.5V) or lower. The resistor 78 of the divider 74 also pulls down the voltage from resistor 46 to a “low” when the divider 74, and thus the status board 36, is connected to the main control board 40. A second op-amp 80 uses a third resistor ladder 82 including resistors 84 and 86 for the switching threshold of the op-amp 80. The positive input 88 of the op-amp 80 is connected between a resistor 90 and the motor brake return output 92. Also, a capacitor 94 is connected to the op-amp 80 at the power input 96 to help provide some noise filtering. The supply voltage Ua for the motor brake and status board 36 is variable, and preferably between 18V-25V.

In operation, the electronic circuit of the motor brake and status board 36 provides a status signal along the single status line 42 to the main control board 40 of whether or not the circuit is connected to the main control board 40, and also whether or not a load is connected to the high side drive 52 via the brake 32. More specifically, if the motor brake and status board 36 are not connected to the main control board 40, and the load is or is not connected to the motor brake and status board 36, a “high” (high=3.5 Volts-5.5 Volts) will always be seen on the status line 42 when the high side drive 52 is in either the on or off state. Further, if the motor brake and status board 36 is connected to the main control board 40 and the load is not connected to the high side drive 52, a “low” (low=less than 0.5 Volts) will always be seen on the status line 42 when the high side drive 52 is in either the on or off state. If the motor brake and status board 36 is connected to the main control board 40 and the load is connected to the high side drive 52, a “low” will be seen on the status line 42 if the high side drive 52 is in the off state. In this case a “high” will only be seen on the status line 42 if the high side drive 52 is on and the load is being driven at a defined minimum current or greater (about 90 mA-125 mA or greater), barring any fault conditions.

Fault conditions can also be determined using the status line 42 and the commanded state of the high side driver 52. For example, a short to Ua (STUa) with the proper load connected to the high side drive 52 looks to the main control board 40 like the control board 40 is not connected to the motor brake and status board 36. Further, a STUa with the load not connected to the high side drive 52 looks to the main control board 40 like an open load. Also, a short to ground (STG) with or without the load connected to the high side drive 52 looks like an open load. Table 1 shows an exhaustive listing of the states aforementioned.

TABLE 1
Brake Status States
	Motor Brake Control Board not connected to
	Main Control Board and/or STUa
	w/ load connected
	Motor Brake and Status Board has Open Load
	and/or STG w/ or w/o load connected and/or
	STUa w/o load connected
	Main Control	Load	FIG. 3,	FIG. 3, Item	High-Side	Status
Condition #	Board Connected?	Connected?	Item 92	62	Drive State	Line
1	NO	X	X	X	OFF	HIGH
2	NO	X	X	X	ON	HIGH
3	YES	YES	NORMAL	NORMAL	ON	HIGH
4	YES	YES	NORMAL	NORMAL	OFF	LOW
5	YES	NO	NORMAL	NORMAL	ON	LOW
6	YES	NO	NORMAL	NORMAL	OFF	LOW
7	YES	YES	NORMAL	STUa	ON	HIGH
8	YES	YES	NORMAL	STUa	OFF	HIGH
9	YES	NO	NORMAL	STUa	ON	LOW
10	YES	NO	NORMAL	STUa	OFF	LOW
11	YES	YES	STUa	NORMAL	ON	HIGH
12	YES	YES	STUa	NORMAL	OFF	HIGH
13	YES	NO	STUa	NORMAL	ON	LOW
14	YES	NO	STUa	NORMAL	OFF	LOW
15	YES	YES	NORMAL	STG	ON	LOW
16	YES	YES	NORMAL	STG	OFF	LOW
17	YES	NO	NORMAL	STG	ON	LOW
18	YES	NO	NORMAL	STG	OFF	LOW
19	YES	YES	STG	NORMAL	ON	LOW
20	YES	YES	STG	NORMAL	OFF	LOW
21	YES	NO	STG	NORMAL	ON	LOW
22	YES	NO	STG	NORMAL	OFF	LOW

Various alternatives are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.

Claims

1. A mobile storage unit comprising: a) a housing adapted to receive and retain items therein;b) a shaft rotatably secured to the housing;c) at least one wheel interconnected with the shaft for rotation therewith;d) an electric motor operably connected to the shaft to rotate the shaft; ande) a motor brake operably connected to the shaft.

2. The storage unit of claim 1 wherein the motor brake is connected to the electric motor.

3. The storage unit of claim 1 wherein the motor brake defines a recess therein within which the shaft is received.

4. The storage unit of claim 3 wherein the recess is positioned in alignment with a central opening extending through the electric motor in which the shaft is positioned.

5. The storage unit of claim 5 wherein the motor brake is operably connected to a motor brake and status controller.

6. The storage unit of claim 5 wherein the motor brake and status controller is operably connected to a main controller via a single status line.

7. The storage unit of claim 6 wherein the motor brake and status controller is configured to provide status signals to the main controller along the single status line concerning the connection of the motor brake and status controller to a load and to the main controller.

8. The storage unit of claim 1 wherein the motor brake is deactivated when a power supply is connected to the motor brake.

9. The storage unit of claim 1 wherein the motor brake is activated when a power supply is disconnected from the motor brake.

10. A method for controlling the movement of a mobile storage unit in a mobile storage unit system, the method comprising the steps of: a) providing a storage unit including a housing adapted to receive and retain items therein, a shaft rotatably secured to the housing, at least one wheel secured to the shaft for rotation therewith, an electric motor operably connected to the shaft to rotate the shaft, and a motor brake operably connected to the shaft; andb) connecting a power supply to the motor brake to allow rotation of the shaft.

11. The method of claim 10 further comprising the step of connecting the power supply to the electric motor to rotate the shaft simultaneously with connecting the power supply to the motor brake.

12. The method of claim 10 further comprising the step of disconnecting the power supply to the motor brake to prevent rotation of the shaft after connecting the power supply to the shaft.

13. The method of claim 12 further comprising the step of disconnecting the power supply from the electric motor simultaneously with disconnecting the supply from the motor brake.

14. The method of claim 10 further comprising the step of providing a status signal from a motor brake and status controller to a main controller along a single status line connecting the motor brake and status controller to the main controller after connecting the power supply.

15. The method of claim 14 wherein the step of providing the status signal comprises: a) sending a signal concerning the status of a load connection to the motor brake and status controller along the single status line; andb) sending a signal concerning the status of a connection between the motor brakeand status controller and the main controller.

16. The method of claim 14 further comprising the step of altering the connection of the power supply to the motor brake in response to the signal sent from the motor brake and status controller to the main controller along the single status line.

17. A status determining system for monitoring drive and load connections, the system comprising: a) a main controller; andb) a status controller operably connected to the main controller along a single status line and configured to detect the status of a connection of the status controller to a load and to the main controller.

18. The system of claim 17 further comprising an electrically operable component connected to and operable by the status controller.

19. The system of claim 18 wherein the electrically operable component is a motor brake.

20. The system of claim 19 wherein the system is operably connected to a motor brake disposed on a mobile storage unit including a rotatable shaft to which the motor brake and an electric motor are connected.