JPH074234U - Parking safety device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent unnecessary damage to the parking brake. [Structure] A pressure switch 2, a speed change switch 3, a speed change solenoid valve 4, a drag prevention relay 5, and a release switch 6. Particularly, the pressure switch 2 and the speed change switch 3 are actuated to operate the speed change solenoid valve 4. A drag prevention relay 5 is provided to activate the parking brake 44 to prevent the parking brake 44 from dragging.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a parking safety device used in a parking brake device equipped in a cargo handling vehicle such as a large forklift truck.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, as a parking brake device equipped in a cargo handling vehicle such as a large forklift, those shown in FIGS. 2 and 3 are known. The parking brake device 40 is basically a hand valve 41 that is manually operated to supply and discharge compressed air from an air pressure source (not shown), and a quick valve that supplies and discharges compressed air in response to the hand valve 41. It consists of a release valve 42, a spring chamber 43 that is actuated by compressed air from now on, and a parking brake (disc brake) 44 that is actuated by it. Press the hand valve to supply compressed air from the air pressure source to the hand valve → quick release valve → spring chamber, and to release the parking brake by extending the spring chamber against the spring. As shown in, pull the hand valve to move the compressed air from the pneumatic source to the hand valve and quick release valve. Released from the, it has become a spring chamber as to operate the parking brake depends on that Ru is shortened in the spring. The parking brake system also functions as an emergency brake (emergency brake), and the parking brake is automatically activated when the airline is damaged. As a parking safety device used in such a parking brake device, the one shown in FIG. 4 is known. The parking safety device 50 basically includes a pressure switch 51 that detects that the parking brake 44 has been actuated, a speed change switch 52 that is actuated by the operation of a speed change lever (not shown), and the operation of the speed change switch 52. A gear shift solenoid valve 53 which is operated by the above to control a gear shift clutch (not shown), an alarm buzzer 54 which issues an alarm, and an alarm buzzer 54 which is activated by the operation of the pressure switch 51 and the gear shift switch 52 so as to activate the alarm buzzer 54. The alarm relay 55 and the alarm relay 55 actuate the parking brake, and when the gear shift lever is operated to actuate the gear shift switch, the alarm buzzer is activated to issue an alarm. However, in such a system, although the alarm buzzer sounds, the shift solenoid valve is activated by the operation of the shift switch, the shift clutch is engaged, and the vehicle runs. The vehicle is driven with the so-called braking parking brake being dragged. Therefore, there is a problem that the parking brake is unnecessarily burned and damaged.

[0003]

[Problems to be solved by the device]

 The present invention was devised in order to solve this problem in view of the above problems, and its purpose is to provide a parking safety device that prevents unnecessary damage to the parking brake. There is.

[0004]

[Means for Solving the Problems]

 The parking safety device of the present invention is basically operated by the pressure switch that detects that the parking brake has been activated, the speed change switch that is operated by operating the speed change lever, and the operation of the speed change switch. Related to the shift solenoid valve that controls the shift clutch, the drag prevention relay that is actuated by the operation of the pressure switch and the shift switch to deactivate the shift solenoid valve, and the operation of the drag prevention relay that can be manually operated. The feature is that it is composed of a release switch that activates the variable-speed solenoid valve instead of the release switch.

[0005]

[Action]

 When the parking brake is activated, the pressure switch detects this and is activated. When the shift lever is operated, the shift switch is operated. When the pressure switch and shift switch are activated, the anti-drag relay is activated and the shift solenoid valve is deactivated. When the shift solenoid valve is deactivated, the shift clutch is disengaged, which prevents dragging. When the release switch is manually operated, the shift solenoid valve is operated regardless of the operation of the drag prevention relay. When the shift solenoid valve is actuated, the shift clutch is brought into the connected state, so that drag running is performed.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an electric circuit diagram showing a parking safety device according to an embodiment of the present invention. The parking safety device 1 is mainly composed of a pressure switch 2, a speed change switch 3, a speed change solenoid valve 4, a drag prevention relay 5, and a release switch 6. The pressure switch 2 detects that the parking brake 44 has actuated. In this example, the pressure switch 2 is provided in the air line from the hand valve 41 of the parking brake device 40 to the spring chamber 43, and when the parking brake 44 is actuated, Is a low-pressure switch that detects when the air pressure is lost due to air pipe rupture, etc. It turns on when there is no pressure and turns off when pressure is applied. One end of the pressure switch 2 is connected to a power supply plus via a parking brake lamp 7 and a fuse 8, and the other end is connected to a negative power supply. An alarm buzzer 9 is connected in parallel to the parking brake lamp 7. A normally open contact of an alarm relay 10 is provided between the alarm buzzer 9 and the pressure switch 2. The speed change switch 3 is operated by the operation of the speed change lever. In this example, similar switches 11 and 12 are operated by the operation of the forward / reverse and speed stage levers (not shown) which are speed change levers. Each of the base terminals is connected to the power source plus through the fuse 13. A back buzzer 14 and a back lamp 15 are provided between the R terminal of the forward / reverse switch 11 and the negative power source. The F terminal and the R terminal of the forward / reverse switch 11 are connected to the negative power source via the diodes 16 and 17 and the coil of the alarm relay 10, respectively. A diode 18 is connected in parallel to the coil of the alarm relay 10. The speed change solenoid valve 4 is operated by the operation of the speed change switch 3 to control the speed change clutch. In this example, the speed change clutch of the transmission (transmission) is forward, reverse, first speed, two speed. Similar solenoid valves (only the solenoid is shown in FIG. 1) 19 to 23 for controlling the third and third speed clutches (not shown) are provided, and diodes 24 to 28 are connected in parallel to each other so that the speed change switch 3 has It is connected to the F terminal, R terminal, 1 terminal, 2 terminal, and 3 terminal. The drag prevention relay 5 is actuated by actuation of the pressure switch 2 and the speed change switch 3 to deactivate the speed change solenoid valve 4. In this example, the coil is connected in parallel to the alarm buzzer 9 and One end of the normally closed contact is connected to the forward solenoid valve 19 and the reverse solenoid valve 20 via diodes 29 and 30, and the other end is connected to the power source minus. The release switch 6 can be manually operated and operates the variable speed solenoid valve 4 regardless of the operation of the drag prevention relay 5. In this example, the release switch 6 is a push button switch and the drag prevention relay 5 is normally closed. It is connected in parallel to the contacts. Next, the operation will be described based on such a configuration. When the hand valve 41 is pulled, compressed air from the air pressure source is released from the hand valve 41 and the quick release valve 42, the spring chamber 43 is shortened by the spring, and the parking brake 44 is actuated. Detects this and is turned on. Then, the parking brake lamp 7 lights up. When the forward / reverse lever of the shift lever is operated, the forward / backward switch 11 of the shift switch 3 is operated from neutral to forward or reverse. Then, the normally open contact of the alarm relay 10 is turned on, the alarm buzzer 9 sounds, and the normally closed contact of the drag prevention relay 5 is turned off, so that the forward solenoid valve 19 and the reverse solenoid valve 20 of the shift solenoid valve 4 are not operated. Since the forward clutch and the reverse clutch of the speed change clutch are disengaged, drag travel is prevented. The parking brake device 40 has a function as an emergency brake, and since the parking brake 44 is automatically applied when the air line is damaged, if the parking brake 44 operates as an emergency, The drag prevention function of will not work and you will not be able to drive. For example, it is dangerous to operate on a railroad crossing. In such a case, by manually operating the release switch 6 to release the drag prevention function, the parking brake 44 can be dragged while traveling. That is, when the release switch 6 is turned on, the forward solenoid valve 19 and the reverse solenoid valve 20 of the shift solenoid valve 4 are activated regardless of the operation of the drag prevention relay 5, and the forward clutch and the reverse clutch of the shift clutch are opened. Since the vehicle is connected, dragging is performed.

Although the alarm buzzer 9 is provided as in the prior art in the previous embodiment, it is not limited to this and may be omitted, for example.

[0008]

[Effect of device]

 As described above, according to the present invention, the following excellent effects can be obtained. (1) A drag prevention relay that is composed of a pressure switch, a speed change switch, a speed change solenoid valve, a drag prevention relay, and a release switch, and that is activated by the operation of the pressure switch and the speed change switch to deactivate the speed change solenoid valve. Since it is equipped with a parking brake, it is possible to prevent dragging of the parking brake and prevent unnecessary damage to the parking brake. (2) Since a release switch is provided that can be manually operated and activates the shift solenoid valve regardless of the operation of the drag prevention relay, even if the parking brake operates as an emergency, the drag prevention function is canceled. It is possible to drive even while dragging the parking brake. (3) Since only the drag prevention relay and the release switch are provided, the structure is relatively simple and can be implemented immediately.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a parking safety device according to an embodiment of the present invention.

FIG. 2 is a pneumatic circuit diagram showing a running state of the parking brake device.

FIG. 3 is a pneumatic circuit diagram showing the operation of the parking brake device.

FIG. 4 is an electric circuit diagram showing a conventional parking safety device.

[Explanation of symbols]

1,50 ... Parking safety device, 2,51 ... Pressure switch,
3, 52 ... Gear change switch, 4, 53 ... Gear change solenoid valve, 5 ... Drag prevention relay, 6 ... Release switch, 7
… Parking brake lights, 8, 13… Fuse,
9,54 ... Alarm buzzer, 10,55 ... Alarm relay, 11
... forward / reverse switch, 12 ... speed stage switch, 14 ... back buzzer, 15 ... back lamp, 16-18, 24-3
0 ... Diode, 19 ... Forward solenoid valve, 20 ...
Reverse solenoid valve, 21 ... 1st speed solenoid valve,
22 ... 2nd speed solenoid valve, 23 ... 3rd speed solenoid valve, 40 ... Parking brake device, 41 ... Hand valve, 42 ... Quick release valve, 43 ... Spring chamber, 44 ... Parking brake.

Claims (1)

[Scope of utility model registration request] 1. A pressure switch for detecting that a parking brake is operated, a speed change switch operated by operating a speed change lever, a speed change solenoid valve operated by operation of the speed change switch to control a speed change clutch, A drag prevention relay that is actuated by the operation of the pressure switch and the speed change switch to deactivate the speed change solenoid valve, and a release switch that is manually operable and operates the speed change solenoid valve regardless of the operation of the drag prevention relay, A parking safety device characterized by being configured from.