JPH09287556A - Air pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable smooth shifting of a differential of a vehicle which is used, for instance, for a locking system from a free to locked condition by suppressing occurrence of erroneous operation of a pressure switch at the operation of a pump part, and thereby attaining improvement of durability of the pressure switch. SOLUTION: An air pump 1 has a pump case 10, a pump 20 which is housed in the pump case 10 and operated by an output of a motor, and a pressure switch part 30 which is housed in the pump case 10 while being communicated with the pump 20, and has a pressure switch 35 operated for interrupting power supply to a motor 2 when pressure generated in the pump 20 is a specified value or more. In such a setup, an orifice 36 is arranged between the pump 20 and the pressure switch 35 for throttling an amount of air to be supplied from the pump 20 to the switch part 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air pump used for operating an actuator incorporated in a rear differential main body in a vehicle rear differential lock system, for example.

[0002]

2. Description of the Related Art Conventionally, for example, an air pump used in a rear differential lock system for a vehicle as described above includes a pump case, a pump portion housed in the pump case and operated by the output of a motor, and a pump. A pressure switch unit including a pressure switch that communicates with the pump unit via a flow path formed in the case and that operates to shut off the power supply to the motor when the pressure generated in the pump unit exceeds a predetermined pressure. There is one that is configured with.

[0003]

However, in the above-mentioned conventional air pump, when the operating pressure of the pressure switch is considerably smaller than the pressure generated in the pump portion, the pump portion is operated (rear differential). The pressure switch malfunctions due to the pulsation of the pump section when the actuator built into the main unit is operated to shift the differential from the free state to the locked state, even though the pressure generated in the pump section is below the specified pressure. It cannot be said that there is a possibility that the power supply to the motor will be cut off due to this, and if the pressure switch malfunctions in this way, not only cannot the differential be smoothly moved from the free state to the locked state, but the motor If it is a DC motor, the starting current of the motor must flow frequently through the pressure switch. Is in, there is a problem that the durability of the pressure switch is significantly reduced, it has been a conventional problem to solve this problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above-mentioned conventional problems, and suppresses the malfunction of the pressure switch during the operation of the pump portion as much as possible to improve the durability of the pressure switch. However, for example, when used in a rear differential lock system of a vehicle, it is possible to smoothly shift the differential from the free state to the locked state, and as a result, to provide an air pump that can improve reliability. It is an object.

[0005]

The invention according to claim 1 of the present invention comprises a pump case, a pump portion housed in the pump case and operated by the output of a motor, and a pump portion in the pump case. An air pump provided with a pressure switch unit which is housed in a communication state and operates in a direction of cutting off power supply to the motor when the pressure generated in the pump unit exceeds a predetermined pressure, wherein the pump unit Between the pressure switch and the pressure switch is characterized in that an orifice for reducing the amount of air sent from the pump unit to the pressure switch unit is provided. It is a means to solve it.

Further, in the air pump according to the second aspect of the present invention, the pressure switch part communicating with the pump part has a switch cover separate from the pump case, and the orifice is provided in the switch cover. It is configured.

Further, in the air pump according to the third aspect of the present invention, the pump case has a flow path for connecting the pump section and the pressure switch section, and the orifice is provided on the flow path.

Here, in the air pump according to the second and third aspects of the present invention, the diameter of the orifice for reducing the amount of air flowing into the pressure switch side is 0.6 mm to 0. The thickness is preferably 8 mm, and more preferably 0.7 mm.

[0009]

In the air pump according to the first aspect of the present invention, even when the operating pressure of the pressure switch is considerably smaller than the pressure generated in the pump portion, when the pump portion is operated, the pump is operated by the orifice. Since the amount of air sent from the pump unit to the pressure switch side is throttled, malfunction of the pressure switch due to pulsation of the pump unit is less likely to occur, that is, power is supplied to the motor when the pressure generated in the pump unit is below a predetermined pressure. As a result, the starting current of the motor does not flow frequently in the pressure switch, and the durability of the pressure switch is improved.For example, this air pump is used for the rear differential lock of the vehicle. When used in a system, actuating the pump will move the differential from the free state to the locked state. It becomes possible to shift to slip, so that the improvement of the reliability can be improved.

Further, in the air pump according to the second aspect of the present invention, since the switch cover which is separate from the pump case is provided with the orifice, the hole forming work for forming the orifice is simplified. On the other hand, in the air pump according to claim 3 of the present invention, since the orifice is provided on the flow path that connects the pump portion and the pressure switch portion, when the pressure switch portion is detachable from the pump case, The pressure switch portion of the air pump will be diverted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the air pump according to the present invention. In this embodiment, the air pump according to the present invention is an air pump for driving an actuator in a rear differential lock system of a vehicle. Indicates.

As shown in FIG. 3, a rear differential lock system for a vehicle includes a rear differential lock section 50 having an actuator built therein and a differential lock switch 6 arranged at a driver's seat of a vehicle C.
1, a lock detection switch 62 provided on the rear differential lock unit 50, an electronic control unit 60 having the air pump 1 and a control unit 63 arranged at the rear of the vehicle C, and the rear differential lock unit 5
It is mainly configured by an air pipe portion 70 that connects the actuator of No. 0 and the air pump 1 of the electronic control portion 60.

As shown in FIGS. 1 and 2, an air pump 1 for sending air to an actuator of a rear differential lock portion 50 has a substantially box-shaped pump case 10 as shown in FIGS.
A pump portion 20 housed in the bottom portion (lower portion in the figure) of the pump case 10 and operated by the output of the motor 2 provided on the side portion; and a pressure switch portion located inside the pump case 10 and above the pump portion 20. The pressure switch unit 30 includes a partition wall 11 provided between the pump unit 20 and the pressure switch unit 30 of the pump case 10 and a print base 13 provided on the cap 12 side of the pump case 10.
The flow path 14 that is housed in the space between the pump section 20 and the pressure switch section 30 has a connection flow path 14 a that is provided in the partition wall 11 and serves as a connection section to the air piping section 70.
Through the.

The pump portion 20 communicates with the flow path 14 via the check valve 3 having a substantially duck bill shape, and further, the actuator side space Sn communicating with the actuator of the rear differential lock portion 50 and the pump portion housing of the pump case 11. A pump movable part 24 including a diaphragm 21 provided between an atmosphere side space Sa communicating with the atmosphere side through an intake / exhaust duct 15 provided in the part, and plates 22 and 23 sandwiching the central part of the diaphragm 21 from the front and back sides. An intake valve 25 is provided at the center of the pump movable portion 24. In this case, the diaphragm 21
Is fixed in a state that its peripheral portion is sandwiched between the pump case 10 and the pump cover 16, and the pump movable portion 24 is the tip portion of the connecting rod 22a integrally provided at the center of the plate 22 on the upper side in the drawing. By connecting the output shaft 2a of the motor 2 via the bearing 4 and interposing the eccentric bush 5 between the bearing 4 and the output shaft 2a, the output of the motor 2 reciprocates in the vertical direction in FIG. ing.

The intake valve 25 has a through hole 22b, one end of which opens at the center of the lower surface of the plate 22 and the other end of which opens at the lower portion of the connecting rod 22a, and one end of the through hole 22b provided at the center of the diaphragm 21. Valve body 26 for opening and closing
The plate 23 is provided with a valve body relief portion 23a, and a communication hole 23b between the valve body relief portion 23a and the actuator side space Sn is formed.

On the other hand, the pressure switch section 30 has a hollow switch case 31, and a switch cover which is mounted in a lower opening of the switch case 31 via a switch diaphragm 32 and has a downward cylindrical section 33a at the center. 33 (switch cover) and a rod-shaped pressure receiving portion 34a provided at the tip (lower end in the drawing) housed in the switch case 31 so as to be slidable in the vertical direction and protruding from the switch diaphragm 32. 33
a, which is also slidably inserted in the vertical direction in the air inflow path 33b of a, a compression coil spring 37 which is provided in the switch case 31 and applies a downward force to the piston 34, and the piston 34 is lifted to move the motor. 2 is provided with a pressure switch 35 that cuts off the power supply to the motor 2 and restarts the power supply to the motor 2 by lowering the piston 34.

The pressure switch section 30 electrically connects the terminals of the pressure switch 35 to a circuit on the print base 13, and also has a downwardly cylindrical portion 33 of the switch cover 33.
By fitting a into the fitting recess 11a formed in the partition wall 11 via the O-ring 6, it is fixed between the print base 13 and the partition wall 11, and the downward cylindrical portion 33a of the switch cover 33. Air inflow path 33
b is communicated with the actuator of the rear differential lock part 50 and the actuator-side space Sn through the flow path 14 provided in the pump case 10, and the piston 34 is operated when the pressure generated in the pump part 20 becomes equal to or higher than a predetermined pressure. Rises and presses the pressure switch 35, which cuts off the power supply to the motor 2.

In this case, the opening portion of the air inflow passage 33b at the tip of the downward cylindrical portion 33a of the switch cover 33 is formed as an orifice 36 having a diameter smaller than that of the air inflow passage 33b, and the pump portion 20 is provided. The amount of air sent from the pressure switch unit 30 to the pressure switch unit 30 is reduced.

Further, the air pump 1 is provided with a solenoid valve 40 as a release valve between the partition wall 11 and the print base 13 in parallel with the pressure switch section 30.

The solenoid valve 40 has a bobbin 41 having a hollow portion, a coil 42 wound around the bobbin 41, and a valve seat centered on a flow path 43 and closely fixed to the lower end of the hollow portion of the bobbin 41. 44 and this valve seat 44
A valve body 45 that is urged upward in the drawing to come into contact with and separate from the valve body, and a valve body sliding portion 46 formed on the upper end side of the hollow portion of the bobbin 41.
And a flow path 47 provided along the longitudinal direction of the valve body sliding portion 46, the solenoid valve 40 has an upper end of a bobbin 41 at the print base 13.
The O-ring 6 is fitted in the fitting recess 13b formed in the partition wall 11 while fitting into the fitting hole 13a formed in
By being fitted through through, it is fixed between the print base 13 and the partition wall 11 like the pressure switch unit 30.

The solenoid valve 40 allows the passage 43 on the valve seat 44 side to communicate with the actuator of the rear differential lock portion 50 and the actuator-side space Sn via the passage 14 provided in the pump case 10, and also allows the valve body to slide. The flow path 47 on the moving part 46 side is communicated with the atmosphere side through the inside of the pump case 11 and the intake / exhaust duct 15, and operates at the stage of freeing the rear differential to actuate the actuator of the rear differential lock part 50. The flow path 14 communicating with is opened to the atmosphere.

In the air pump 1, when the differential lock switch 61 is turned on, the motor 2 of the air pump 1 is activated by a command from the control unit 63 of the electronic control unit 60, and the suction operation is started in the pump unit 20.

At this time, the solenoid valve 40 is in a closed state, and when the pump movable portion 24 of the pump portion 20 starts the vertical reciprocating operation, the air sucked through the intake / exhaust duct 15 passes through the intake valve 25 to the atmosphere. Side space S
The air sent from a to the actuator-side space Sn and sent to the actuator-side space Sn is pressure-fed to the actuator of the rear differential lock unit 50 via the flow path 14, the connection flow path 14a, and the air piping unit 70, and the differential Will shift from the free state to the locked state.

During this time, the downwardly facing cylindrical portion 33a of the switch cover 33 of the pressure switch portion 30 is passed through the flow path 14.
Air is also supplied to the air inflow path 33b of the motor 20, and when the pressure generated in the pump unit 20 becomes equal to or higher than a predetermined pressure, the piston 34 rises and presses the pressure switch 35 to supply power to the motor 2. When the supply is interrupted and the pressure becomes equal to or lower than the predetermined pressure, the piston 34 descends to restart the power supply to the motor 2, so that the pressure generated in the pump unit 20 is maintained at the predetermined magnitude. The Rukoto.

While the pump unit 20 is operating,
Since the amount of air supplied to the air inflow passage 33b of the downward cylindrical portion 33a of the switch cover 33 of the pressure switch portion 30 is narrowed down by the orifice 36, the pressure switch 35 operates in comparison with the pressure generated in the pump portion 20. Even if the pressure is quite low, the pump part 2
The up and down movement of the piston 34 due to the pulsation of 0 does not occur, and the malfunction of the pressure switch 35 is less likely to occur. Therefore, the starting current of the motor 2 does not flow frequently in the pressure switch 35, the durability of the pressure switch 35 is improved, and in addition, the differential smoothly moves from the free state to the locked state. As a result, the reliability will be improved.

On the other hand, when the differential lock switch 61 is turned off, the motor 2 of the air pump 1 is stopped by the command from the control unit 63 of the electronic control unit 60, and the suction operation of the pump unit 20 is stopped.
Since the solenoid valve 40 is opened to open the flow path 14 communicating with the actuator of the rear differential lock portion 50 to the atmosphere, the locked state of the rear differential is released.

In this air pump 1, the pump case 10
Since the orifice 36 is provided in the switch cover 33 which is a separate body from the above, the hole forming work for forming the orifice 36 becomes simple.

FIG. 4 shows another embodiment of the air pump according to the present invention. In this embodiment also, the air pump according to the present invention is an air pump for driving an actuator in the rear differential lock system of a vehicle. Show.

As partially shown in FIG. 4, the air pump 81 in this embodiment is the air pump 1 according to the previous embodiment.
The difference from the above is that the orifice 86 is provided on the flow path 14, that is, the communicating portion of the flow path 14 with the pressure switch unit 30 is formed as the orifice 86, and other configurations are the same as those of the previous embodiment. It is the same as the air pump 1.

In this air pump 81, since the communicating portion of the flow path 14 with the pressure switch portion 30 is formed as the orifice 86, the pressure switch portion 30 is attached to and detached from the pump case 10 as in this embodiment. If it is possible, the pressure switch portion 30 of the air pump 81 will be diverted.

The detailed construction of the air pump according to the present invention is not limited to the construction of the above embodiment.

[0033]

As described above, according to the first aspect of the present invention.
Since the air pump according to the above has the above-mentioned configuration, even if the operating pressure of the pressure switch is considerably smaller than the pressure generated in the pump section, the pulsation during the operation of the pump section prevents the pressure switch from malfunctioning. Can be stopped,
Therefore, since the starting current of the motor does not flow frequently to the pressure switch, the durability of the pressure switch can be improved.For example, when this air pump is used in the rear differential lock system of the vehicle, the differential is free. It is possible to smoothly shift from the state to the locked state, which brings about a very excellent effect that the reliability can be improved.

Further, since the air pump according to claim 2 of the present invention has the above-mentioned structure, it is possible to easily perform the hole forming work when forming the orifice, and further, the air pump according to claim 3 of the present invention. Then, with the above-described configuration, when the pressure switch portion is attachable to and detachable from the pump case, the pressure switch portion of the air pump can be diverted, which is a very excellent effect.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing an embodiment of an air pump according to the present invention.

FIG. 2 is a cross-sectional explanatory view from the right side of the air pump shown in FIG.

FIG. 3 is a perspective view illustrating an arrangement state of a rear differential lock system including the air pump of FIG. 1 in a vehicle.

FIG. 4 is an enlarged cross-sectional explanatory view of an orifice portion showing another embodiment of the air pump according to the present invention.

[Explanation of symbols]

 1,81 Air pump 2 Motor 10 Pump case 14 Flow path 20 Pump part 30 Pressure switch part 33 Switch cover (switch cover) 35 Pressure switch 36,86 Orifice

Claims (3)

[Claims] 1. A pump case, a pump unit housed in the pump case and operated by the output of a motor, and a pressure generated in the pump unit housed in communication with the pump unit at a predetermined pressure. In the air pump provided with a pressure switch unit having a pressure switch that operates in a direction to shut off the power supply to the motor at the above-mentioned stage, between the pump unit and the pressure switch, the pressure switch from the pump unit is provided. An air pump characterized by being provided with an orifice for restricting the amount of air sent to the section. 2. The air pump according to claim 1, wherein the pressure switch part communicating with the pump part has a switch cover separate from the pump case, and the orifice is provided in the switch cover. 3. The air pump according to claim 1, wherein the pump case has a flow path that connects the pump section and the pressure switch section, and the orifice is provided on the flow path.