JPH08133033A - Eddy current type speed reducing device - Google Patents

Abstract

PURPOSE: To prevent a drag of a braking drum by releasing braking by means of an actuator when a pressure of a fluid pressure tank becomes the preset value or less so as to smoothly drive a vehicle continuously. CONSTITUTION: A magnet supporting cylinder 13, in which multiple magnets 13a are connected with each other while their magnetic poles toward a braking drum 15 being alternated with each other in the circumference direction, is connected to an actuator B driving the magnet supporting cylinder 13 to a braking position, in which it is projected to the inside of the braking drum 15 connected to a rotary shaft 18, or to a non-braking position, in which it is retracted from the braking drum 15. A solenoid switching valve 10 cutting off communication between a fluid pressure tank 12 and an external end chamber 23 in the actuator B during demagnetization is inserted and connected between them, while a solenoid switching valve 10a connecting the fluid pressure tank 12 and an internal end chamber 24 together during demagnetization is inserted and connected between them. A relay switch 9 is inserted and connected to an energizing circuit for the respective solenoid switching valves 10, 10a. On the basis of an output, which is based on a signal from a pressure sensor 11 when the pressure of the fluid pressure tank 12 becomes the preset value or less, from an electronic controlling unit 7, the relay switch 9 is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current type speed reducer for a vehicle, and more particularly to an eddy current type speed reducer for generating a braking force when a magnet support cylinder projects into a braking drum by a fluid pressure actuator.

[0002]

As disclosed in Japanese Patent Laid-Open No. 3-86060, in a conventional eddy current type speed reducer, a braking torque based on an eddy current is applied to a braking drum when an actuator causes a magnet supporting cylinder to project inside a braking drum. appear. By the way, if the pressure in the fluid pressure tank drops during braking due to some failure,
Due to the actuator, the magnet support cylinder cannot be pulled out from the inside of the braking drum, the braking drum is dragged, and smooth operation of the vehicle cannot be continued thereafter.

In order to solve the above-mentioned problems, conventionally, a strong return spring is mounted inside the actuator, and the pressurized fluid in the outer end chamber of the actuator is discharged to the outside. The brake is released from the inside of the braking drum to release the braking. However, the above-mentioned current type speed reducer requires a large-sized and large-output actuator capable of pushing the magnet support cylinder into the inside of the braking drum against the force of the return spring during braking, which makes mounting on a vehicle difficult.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide, when the pressure in a fluid pressure tank falls below a predetermined value,
It is an object of the present invention to provide an eddy current type speed reducer in which braking is released in advance by an actuator so that smooth vehicle operation can be continued.

[0005]

In order to achieve the above object, the structure of the present invention has a magnet supporting cylinder supported on the vehicle body side, a braking drum connected to a rotating shaft, and a magnet supporting cylinder inside the braking drum. In an eddy current type speed reducer including an actuator that drives a protruding braking position and a non-braking position that is retracted from a braking drum, and a fluid pressure tank that is a pressure source of the actuator, the pressure in the fluid pressure tank is below a predetermined value. The actuator is driven by the output of the electronic control unit based on the signal of the pressure sensor when the contact condition is reached, and the magnet support cylinder is placed in the non-braking position.

[0006]

[Function] An electromagnetic switching valve that connects the fluid pressure tank and the inner end chamber of the actuator to each other during demagnetization and a solenoid switching valve that disconnects the fluid pressure tank and the outer end chamber from each other when demagnetized. Each is inserted and connected. When the pressure in the fluid pressure tank falls below a predetermined value during braking, the electromagnetic switching valve immediately switches, the pressurized fluid in the fluid pressure tank is supplied to the inner end chamber of the actuator, and the magnet support cylinder is pulled out from the braking drum. The alarm is activated at the same time when the braking is released.

[0007]

FIG. 1 is a schematic diagram of an eddy current type speed reducer using a permanent magnet (this is simply called a magnet) according to the present invention. The eddy current type speed reducer A includes a braking drum 15 having a cooling fin 16, which is connected to a large number of spokes 17 protruding radially outward from a boss portion 18a of a rotary shaft (for example, an output shaft of a transmission of a vehicle) 18. ing. A large number of ferromagnetic plates 14a are coupled to the inner end of the immovable guide cylinder 14 made of a non-magnetic material and projecting into the braking drum 15 at equal intervals in the circumferential direction. On the other hand, the outer end of the guide cylinder 14 has an inner peripheral surface to which a cylinder 14b made of a magnetic material is coupled. On the outer peripheral surface of the magnet support cylinder 13 made of a magnetic material, the magnets 13 facing the ferromagnetic plates 14a are provided.
a is coupled so that the polarities are alternately different in the circumferential direction.

The magnet support cylinder 13 has a plurality of actuators B.
As a result, it is driven to the illustrated non-braking position and the braking position protruding into the braking drum 15. Actuator B has piston 22 fitted in cylinder 21 to define outer end chamber 23 and inner end chamber 24, and rod 25 connected to piston 22.
Is projected to the outside through the inner end chamber 24, and the magnet support cylinder 1
Combined with 3. The air tank 12 is connected to the outer end chamber 23 of the actuator B via the electromagnetic switching valve 10 and to the inner end chamber 24 via the electromagnetic switching valve 10a. The power source battery 8 is connected to the electromagnetic switching valves 10 and 10a and the alarm device 30 via the relay switch 9, respectively.

The relay switch 9 has a signal when the retarder switch 3 mounted on the steering cylinder 2 is closed and a signal from the accelerator sensor 4 when the accelerator pedal is released.
The clutch sensor 6 when the clutch pedal is released
And the output of the electronic control unit 7 based on In the case of a vehicle equipped with an automatic transmission, the clutch sensor 6 need not be provided.

According to the present invention, when the pressure in the air tank 12 drops,
The output of the electronic control unit 7 based on the signal of the pressure sensor 11 when the pressure in the air tank 12 becomes equal to or lower than a predetermined value in order to avoid the state where the braking cannot be released and to allow the smooth operation of the vehicle to be continued. The braking is released by.

As shown in FIG. 2, the electromagnetic switching valve 10 opens the outer end chamber 23 to the outside when demagnetized, and connects the outer end chamber 23 to the air tank 12 when excited. On the contrary, the electromagnetic switching valve 10a communicates the inner end chamber 24 with the air tank 12 during demagnetization, and releases the inner end chamber 24 during excitation with the outside.

In normal operation, when the clutch pedal is released, the retarder switch 3 is closed and the accelerator pedal 4 is released, the relay switch 9 is closed by the output of the electronic control unit 7, and the power source battery 8 to the relay switch 9 are closed. Then, the electromagnetic switching valves 10 and 10a and the alarm device 30 are energized. The electromagnetic switching valves 10 and 10a are switched from the state shown in FIG. 2, and the pressurized air in the air tank 12 is changed to the electromagnetic switching valve 10.
The air in the inner end chamber 24 is discharged to the outside through the electromagnetic switching valve 10a. Therefore, the magnet support cylinder 13 is pushed into the inside of the braking drum 15 by the piston 22, and the rotating braking drum 15 is moved to the magnet 13a.
Receives a braking torque based on the eddy current when traversing the magnetic field exerted on the braking drum 15 via the ferromagnetic plate 14a.

When the pressure in the air tank 12 drops below a predetermined value po during braking, the relay switch 9 is opened by the output of the electronic control unit 7 based on the signal from the pressure sensor 11, and the electromagnetic switching valves 10 and 10a are opened as shown in FIG. Switch to the position shown in. Therefore, the pressurized air in the air tank 12 is supplied to the inner end chamber 24 via the electromagnetic switching valve 10a, and the air in the outer end chamber 23 is discharged to the outside via the electromagnetic switching valve 10. The magnet support cylinder 13 is pulled out from the braking drum 15, the magnetic field is not applied to the braking drum 15, and the braking is released.

FIG. 3 is a flow chart of a control program for performing the above control by the electronic control unit 7. The control program starts at p11 and determines at p12 whether the accelerator pedal is released. If the accelerator pedal is not released, open the relay switch 9 on p13 and then p18
Go to.

If the accelerator pedal is released at p12, it is determined at p14 whether or not the clutch pedal is released. P if the clutch pedal is not released
Proceed to step 13, and if the clutch pedal is released, p
At 15, it is determined whether or not the retarder switch 3 is closed. If the retarder switch 3 is not closed, the process proceeds to p13. If the retarder switch 3 is closed, it is determined at p16 whether the pressure in the air tank 12 is higher than the predetermined value po. If the pressure in the air tank 12 is lower than the predetermined value po, p13
When the pressure in the air tank 12 is higher than the predetermined value po, the relay switch 9 is closed at p17, and the process ends at p18.

In the case of the above-mentioned actuator using air pressure, an electromagnetic three-way valve is used for each electromagnetic switching valve. The pressure sensor may be connected to the air tank 12, but if it is provided at a portion close to the actuator B, for example, at the point c in FIG. 1, water in the air freezes in the conduit between the air tank 12 and the point c. Even in the case where the pressurized air is not sufficiently supplied to the actuator B due to the above reasons, the braking releasing operation by the electronic control unit 7 works.

The present invention has the same effect even in the case of an actuator using hydraulic pressure instead of air pressure.

In the above-described embodiment, the eddy current type speed reducer of the type having the magnet support cylinder in which a large number of magnets are coupled to the braking drum so that the magnetic poles are alternately different in the circumferential direction has been described. The present invention is not limited to, for example, a coil type magnet, a magnet supporting cylinder supported on the vehicle body, a braking drum connected to the rotating shaft, and a braking position where the magnet supporting cylinder is projected into the braking drum. The present invention can be widely applied to an eddy current type speed reducer including an actuator driven to a non-braking position retracted from a braking drum, and a fluid pressure tank which is a pressure source of the actuator.

[0019]

As described above, according to the present invention, the magnet supporting cylinder supported on the vehicle body side, the braking drum connected to the rotating shaft, the braking position where the magnet supporting cylinder is projected into the braking drum, and the withdrawal from the braking drum. In an eddy current type speed reducer equipped with an actuator that is driven to a non-braking position and a fluid pressure tank that is the pressure source of the actuator, the signal of the pressure sensor when the pressure of the fluid pressure tank becomes equal to or lower than a predetermined value. Since the actuator is driven by the output of the electronic control unit based on the above, and the magnet support cylinder is placed in the non-braking position, it is not necessary to provide a strong return spring in the actuator, and braking and braking release by the actuator with small size and small output. Can be used to help reduce the weight and cost of the actuator, and reduce the vehicle mounting space.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an eddy current type speed reducer according to the present invention.

FIG. 2 is a circuit diagram showing connection of electromagnetic switching valves in the same eddy current type speed reducer.

FIG. 3 is a flow chart of a control program of the eddy current type speed reducer.

[Explanation of symbols]

B: Actuator 7: Electronic control device 9: Relay switch 10, 10a: Electromagnetic switching valve 11: Pressure sensor 12: Air tank 13: Magnet support cylinder 13a: Magnet 1
4: Guide cylinder 14a: Ferromagnetic plate 15: Braking drum 1
4b: cylindrical body 23: outer end chamber

Claims (3)

[Claims] 1. A magnet supporting cylinder supported on a vehicle body side, a braking drum connected to a rotating shaft, and a magnet supporting cylinder driven to a braking position protruding into the braking drum and a non-braking position retracted from the braking drum. In an eddy current type speed reducer equipped with an actuator and a fluid pressure tank which is a pressure source of the actuator, the output of the electronic control unit based on the signal of the pressure sensor when the pressure of the fluid pressure tank falls below a predetermined value. An eddy current type speed reducer characterized by driving an actuator to bring a magnet support cylinder to a non-braking position. 2. An electromagnetic switching valve for disconnecting the fluid pressure tank and the outer end chamber of the actuator during demagnetization, and an electromagnetic switching valve for communicating with the inner end chamber during demagnetization. Insert and connect the relay switch to the energizing circuit of each solenoid directional control valve, and connect the relay switch by the output of the electronic control unit based on the signal of the pressure sensor when the pressure in the fluid pressure tank falls below a predetermined value. The eddy current type speed reducer according to claim 1, which is opened. 3. A signal from a pressure sensor when the pressure in the fluid pressure tank falls below a predetermined value, an accelerator sensor signal when the accelerator pedal is released, and a clutch when the clutch pedal is released. The eddy current type speed reducer according to claim 1, wherein the relay switch is opened by an output of an electronic control device based on a signal of a sensor.