Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2000-04-11
2001-11-13
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C310S198000, 33
Reexamination Certificate
active
06315527
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a motor-driven compressor which is driven by a driving device connected to a low-voltage power source and through which a relatively large electric current flows.
2. Description of the Related Art
Conventional electric cars or hybrid cars are generally provided with a plurality of 12-volt batteries, and a motor-driven compressor for an air conditioner mounted therein is supplied with, for example, 200 to 300 volts of electricity.
FIG. 1
depicts a motor-driven compressor
2
for an air conditioner mounted in a conventional electric car. The compressor
2
has a shell that is made up of a generally cylindrical shell
4
, a lower shell
6
joined to one end of the generally cylindrical shell
4
, and an upper shell
8
joined to the other end of the generally cylindrical shell
4
. The shell accommodates an electric motor
10
and a compression mechanism
12
driven by the electric motor
10
. The electric motor
10
includes a stator
10
a
secured to the generally cylindrical shell
4
and a rotor
10
b
secured to a crank shaft
14
constituting the compression mechanism
12
.
An electric power from a power source (not shown) is supplied to the motor-driven compressor
2
via a driving device (not shown), a wiring system (not shown), and the like. In applications where the voltage of the power source ranges from 200 to 300 volts, an electric current of only 6 to 7 amperes flows through electric wires, pins of a terminal
16
secured to the upper shell
8
of the motor-driven compressor
2
, and lead wires
18
connected to the pins. Accordingly, the diameter of the electric wires is relatively small and, for example, 2-mm
2
electric wires are generally used.
In some motor-driven compressors, an electric current larger than that in the compressors referred to above flows. If an electric current of, for example, 15 to 20 amperes flows in the compressors, wiring must be conducted using about 3-mm
2
electric wires. In that case, a terminal larger than the terminal
16
shown in
FIG. 1
is mounted to the upper shell
8
.
Recently, a study of electric cars or hybrid cars for practical use is being made at a high pace, and from the viewpoint of safety, there is a tendency to use a 36-volt power source, for example, by connecting three 12-volt batteries in series.
However, if a motor-driven compressor is supplied with 36 bolts of electricity, a large electric current of about 60 to 80 amperes flows through the terminal and the lead wires of the motor-driven compressor via the wiring system. Accordingly, it is necessary for the electric wires to have an increased diameter to allow the electric current of 60 to 80 amperes to flow therethrough. The increase in diameter hardens the electric wires and reduces the degree of freedom of wiring, thus making the wiring very difficult.
Returning to
FIG. 1
, the lead wires
18
of stator windings have respective tab receptacles
19
connected thereto, while the terminal
16
secured to the upper shell
8
has pins and tabs welded to respective pins. In assembling the motor-driven compressor
2
, the tab receptacles
19
of the lead wires
18
are connected to the tabs of the terminal
16
. However, because the internal space of the upper shell
8
is extremely limited, if the diameter of the lead wires
18
is large, it is very difficult to connect the tab receptacles
19
to the tabs of the terminal
16
. Furthermore, if the diameter of the lead wires
18
is large, the heat radiating properties at the connecting portions decrease.
In addition, where a motor-driven compressor is installed in an automotive vehicle, it is necessary to take the resistance to vibration, the resistance to impact, and the like into due consideration. In particular, a hermetic terminal for connection with an external power source requires good hermetic properties or resistance to thermal shock, and also requires a reduction in contact resistance in order to maintain the current-carrying ability in view of the use of a low-voltage and large-current power source.
Conventionally, as shown in
FIGS. 2A and 2B
, the terminal
16
secured to the upper shell
8
is connected to the external power source by press-fitting tab receptacles
22
connected to external electric wires to external tabs
20
secured to the terminal
16
. However, a mere press-fitting increases the contact resistance, and if the diameter of the electric wires is large, there arises a problem in that the mutually connected elements are easily disconnected from each other by vibration.
Also, because the wiring of the large-diameter lead wires is difficult, there is a danger of the lead wires being brought into contact with the shell in the vicinity of the terminal, giving rise to a leakage of electricity.
SUMMARY OF THE INVENTION
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly an objective of the present invention to provide a highly reliable motor-driven compressor driven with electricity of a low voltage and a large electric current.
Another objective of the present invention is to provide the motor-driven compressor of the above-described type that is capable of enhancing the workability during wiring.
In accomplishing the above and other objectives, the motor-driven compressor according to the present invention is driven by a driving device via a single-circuit external wiring system and includes a closed vessel, a compression mechanism accommodated in the closed vessel, and an electric motor accommodated in the closed vessel for driving the compression mechanism, wherein the electric motor including three-phase stator windings each having two parallel circuits.
This construction can cope with the supply of a large electric current without increasing the diameter of electric wires within a limited space inside the closed vessel. Accordingly, the workability is not lowered.
The motor-driven compressor further includes a terminal secured to the closed vessel and having a plurality of pins. Each of the plurality of pins has two tabs secured thereto for connection with the two parallel circuits of the stator winding of each phase. This arrangement ensures sufficient heat radiating properties without increasing the contact resistance.
Conveniently, all the tabs extend radially or parallel to one another in the same direction, thereby maintaining a predetermined distance between the two tabs for each phase and preventing interference between the neighboring phases. Furthermore, the workability during wiring is enhanced.
The motor-driven compressor also includes plural pairs of tab receptacles, each pair of which is connected to the two tabs of each of the plurality of pins, wherein each pair is constituted by two tab receptacles from which respective lead wires extend in opposite directions and which are paired such that the lead wires extend in the same direction. By this construction, each pair of tab receptacles can be readily fitted to the corresponding tabs, making it possible to enhance the workability during wiring.
Preferably, each of the plurality of pins has an externally threaded portion, to which a nut is tightened for connection with the external wiring system. This arrangement prevents the mutually connected elements from being disconnected, for example, by vibration and provides a highly reliable motor-driven compressor.
In another form of the present invention, a motor-driven compressor includes a closed vessel having a terminal secured thereto for connection with an external wiring system, a compression mechanism accommodated in the closed vessel, an electric motor accommodated in the closed vessel for driving the compression mechanism, a plurality of lead wires for connecting a plurality of stator windings of the electric motor to the terminal, each of the plurality of lead wires being divided into two lead wires, and a plurality of intermediate connecting portions each for connecting the two lead wires.
This construction ensures a sufficien
Fukumoto Minoru
Funami Hitoshi
Makino Masahiko
Nishii Nobuyuki
Freay Charles G.
Liu Han L.
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Motor-driven compressor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Motor-driven compressor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motor-driven compressor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2569153