GB2065272A

GB2065272A - A control valve with a mechanical remote control device

Info

Publication number: GB2065272A
Application number: GB8037198A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-12-11
Filing date: 1980-11-20
Publication date: 1981-06-24
Also published as: FR2472127B1; GB2065272B; DE2949703A1; IT8026492A0; FR2472127A1; IT1134619B

Abstract

The control slide 5 of a control valve 2 is adjustable with the aid of a mechanical remote control device 3. The latter has a manually actuated lever 34 and a pulling means in the form of a cable 39 coupled to the lever. The cable is connected to the control slide 5 and a return spring 6 additionally engages the control slide in such a manner that the cable is permanently under tension. The control valve 2 is arranged so that the control slide 5 can be moved by the return spring 6 into an emergency switching position adjacent to the positions designed for controlling an hydraulic drive 18 if the cable should rupture. In the said emergency switching position, the control slide 5 effects the stopping of the hydraulic drive 18. The control valve, Fig. 2 (not shown), has neutral, lower, raise float and emergency control positions. The control valve and actuating lever 34 are normally biased to neutral by a resetting mechanism 36, having one or more springs. The actuating mechanism comprises a spring pressed detent 37 which is releasable by electromagnet 75 on either pressing a bolt on 71 to actuate a switch 70 or by limit switches 25, 26 on the hydraulic drive 18. Electromagnets 15 of a flashing unit 14 preventing conitation are actuated by switch 78. <IMAGE>

Description

SPECIFICATION A control valve with a mechanical remote control device The invention originates from a control valve according to the preamble of claim 1. A control valve provided with a valve slide member is already known, which is moved into three positions by means of a mechanical remote control device which has a manually actuated lever, the central position of which is the neutral position. The two other positions are the control positions for the forward and reverse operation of an hydraulic drive in the form of, for example, a cylinder with a piston. Such a drive is arranged, for example, on a tractor, excavator or the like and serves for the raising and lowering of working equipment. The remote control device has a latching mechanism coupled to the manually actuated lever.It has a slide portion with detent notches and a latching element which is forced by means of a latching spring against the slide portion and its detent notches. A resetting device formed from compression springs and spring washers directly engages the slide portion and attempts to slide the slide portion out of each of the control positions towards its neutral position.

Moreover, the remote control device also has a pull cable hooked into the slide portion and connected to the slide valve member, a return spring acting on the slide valve member and permanently tensioning the pull cable as well as a breakdown safety device which directly engages the slide valve member. The breakdown safety device includes a movable release controller comprising a tensionable control spring and a nonmovable release member. The release controller is unlatched by means of the release member The unlatching takes place when, after rupturing of the pull cable, the return spring has pushed the slide valve member together with the release controller so far that the latter strikes the release member.After the unlatching, the pretensioned control spring forces the slide valve member against its previous direction of movement and through the next adjacent control position into its neutral position. The disadvantage is that during the time which the slide valve member requires to reach its neutral position, the hydraulic drive is switched in and damage can occur. Moreover, the technical expenditure for the complicated release controller and the release member is high. In addition, the danger exists that the release controller becomes ineffective as a result of improper servicing or repair.

Advantages of the Invention The control valve in accordance with the invention and its mechanical remote control device comprising the characterising features according to claim 1 has the advantage that, when the pulling means (for example cable) breaks, the control member for stopping the hydraulic drive is arranged to move only in one direction which takes place within a particularly short period.

Thus, the danger that a breakdown occurs after rupturing of the cable is quite considerably reduced by the invention. A further advantage of the control valve in accordance with the invention consists in the fact that it is considerably simpler in construction and for that reason is cheaper to manufacture. Due to its more simple construction, it is also more accessible. Moreover, the danger that the emergency switching off could fail to operate as a result of an improper maintenance or repair of a breakdown safety device especially arranged to be operated by a release member, is overcome.

The features set forth in the other claims facilitate further developments and improvements of th'e control valve set forth in claim 1. The further developments with the features according to claims 5 to 9 have the advantage that they can be operated particularly easily and are therefore sensitive. These further developments can be applied directly or through control valves actuated by push-pull linkages. Because of the electromagnets, the embodiment comprising the features according to claim 6 has the additional advantage that it can also be remote controlled by limit position switches, pressure limiting switches and the like. The embodiment comprising the feature according to claim 11 is particularly economical since a current source which is provided anyway is also used for actuating the blocking unit.

Drawings An embodiment of the invention is illustrated in the drawings and is described in detail in the following specification. Figure 1 shows a control valve provided with a remote control device partially in section and partially diagrammatic, Figure 2 shows a detail of the embodiment according to Figure 1, and Figure 3 shows further details of the embodiment according to Figure 1 in section.

Description of the Embodiment In Figure 1, a control valve is referenced 2 which is connected to a remote control device 3.

The control valve 2 has a valve housing 4, a control member in the form of a control slide 5 and a return spring 6 engaging the control slide 5 and attempting to push the control slide 5 towards the right. The valve housing 4 is connected through a line 7 to a pump 8. A suction connection 9 from the pump 8 is immersed in a container 10 for hydraulic fluid. A return line 11 is arranged between the valve housing 4 and the container 10. A pressure switch 1 3 is connected to the line 7 through a further line 12. A blocking unit 14 is connected to an hydraulic drive 1 8 through lines 16, 1 7. This hydraulic drive 1 8 consists of a double acting cylinder 1 9 and a piston rod 20 projecting out of the cylinder.Through a pin 20', the piston rod 20 engages a jib 21 which carries a shovel 22. The jib 21 is mounted by means of an axis 23 on a tractor, excavator or the like. A control cam 24 is connected to the jib 21. Two switches 25, 26 are so arranged on the tractor that, when the jib reaches predetermined pivotal positions, they are actuated by the control cam 24.

The remote control device 3 has a housing 30, a housing base 31, a first pivot axis 32 arranged in the housing 30, a segment 33 carried by the said pivot axis, an actuating means fixed to the segment 33 and designed in the form of a manually actuable lever 34 provided with a handle 34', a pin 35 fixed to the segment 33, a resetting unit 36 fixed to the housing 30, a latching mechanism 37 and a flexible pulling means in the form of a cable 39.

The resetting unit 36 consists of a housing 41, a rod 42 provided with axial abutment surfaces 43, 44, two spring washers 45, 46 loosely engaging around the rod 42 between the said axial abutment surfaces 43, 44 and a return spring 47 arranged between the said spring washers 45, 46 and loosely engaging around the rod 42. The rod 42 is mounted for longitudinal displacement both in the housing 41 and in the housing 30. The return spring 47 acts so that when the latching mechanism 37 is unlatched in a manner to be described later, the rod 42 is forced back into the illustrated neutral position after any displacement out of the neutral position. The rod 42 is pivotally connected to an intermediate member 49 by a pin 48. The intermediate member 49 is pivotally connected to the segment 33 by means of the pin 35.Thus, a pivoting of the segment 33 by means of the manually actuated lever 34 causes the rod 42 to be displaced. The cable 39 is connected to a nipple 50 which is hooked into the rod 42. The cable 39 extends through a guide grommet 51 into a grommet holder 52 fixed to the valve housing 4. A connecting piece 53 which is connected on the one hand to the cable 39 and on the other hand to an actuating rod 54, is mounted for longitudinal displacement within the grommet holder 52. The actuating rod 54 extends through a sealing ring 55 arranged in the grommet holder to the control slide 5 and is connected to the latter with the aid of a clamping device 56. A hollow adjusting screw 57 is inserted between the guide grommet 51 and the grommet holder 52.

The control valve 2, formed as a 6/5-way valve, is illustrated diagrammatically in Figure 2. The control slide 5 is movable within the valve housing 4 into five different positions I, II, Ill, IV and V. The central position Ill is the neutral position. When the control slide 5 is located in the said neutral position Ill, the lines 7, 11, 16 and 1 7 are closed.

If the control slide 5 is brought into the next position IV, towards the right in Figure 1 , then the lines 7 and 16 as well as the lines 11 and 17 are connected to one another. The cylinder 1 9 is influenced whereupon the jib 21 and the shovel 22 are raised. If the control slide 5 is moved through the neutral position Ill into the control position Il against the action of the return spring 6, then the jib and the shovel 22 are lowered. In the position I, the lines 1 6 and 1 7 are connected to the return line 11 and the line 7 coming from the pump 8 is closed. Bringing the control slide 5 into the position I, permits a force acting from the outside to move the piston rod 20 freely in the direction of the force.Thus, this control position I represents a free movement position. If the control slide 5 is allowed to follow the action of the return spring 6, then it is moved into the position V which, proceeding from the neutral position Ill, is adjacent to the position IV. The control slide 5 and the valve housing 4 surrounding it are designed in such a manner that in the position V of the control slide 5 the same control action occurs, for example, as though the control slide 5 were in its neutral position III. In this manner, the said position V forms an emergency switching in or switching out position.

The latching mechanism 37 is formed by the segments 33, which carries three detent notches 60, 61 and 62 on its periphery, a latching member 54 which carries a latching pawl 65 pointing towards the segment 33 and which is mounted by means of a second pivotal axis 66 arranged in the housing 30, and a latching spring 67. The latching spring 67 is inserted in the housing base 31 and pivots the latching member 64 towards the segment 33. With a suitable pivotal adjustment of the segment 33, the latching pawl 65 engages in one of the detent notches 60, 61 or 62 and produces a pivotal resistance at the segment 33.

An unlatching device 70 is associated with the latching mechanism 37. The unlatching device 70 consists of a push-button 71 mounted for displacement in the longitudinal direction of the manually actuated lever 34, a return spring 72 for the push-button 71, a push rod 73 arranged beyond the push-button 71, a switch 74 fixed to the segment 33 and actuable through the push rod 73 and an electromagnet 75. A pressure on the button 71 actuates the switch 74. The electromagnet 75 is switched in or switched out by the switch 74 according to its switching position. By means of an anchor rod 76, the electromagnet 75 acts on an arm 64' arranged on the latching member 64 in such a manner that the latching member 64 is pivoted against the action of the latching spring 67.Thus, by switching on the electromagnet 75, the latching member 64 can be pivoted away from the segment 33 so that the latching pawl 65 releases the segment 33.

A compensating spring 77 which pushes against the spring washer 46 is arranged within the resetting unit 36. This compensating spring 77 operates against the return spring 6 through the cable 39 so that only very little force is required to displace the control slide 5 in alternate directions from the region of its neutral position lil, by means of the manually actuated lever 34. The resetting unit 36 acts so that the rod 42 and the control slide 5 are moved into their neutral positions when the latching pawl 65 does not engage in one of the detent notches 60, 61. The adjusting screw 57 is adjusted in such a manner that with the rod 42 located in the neutral position, the control slide 5 is also located in its neutral position III.

The control valve 2 and its remote control device 3 operate in the following manner. On pivoting the manually actuated lever 34 clockwise from the neutral position Ill, the rod 42 and the spring washer 46 are pushed against the action of the return spring 47. Thus, the nipple 50 is moved in the direction of the guide grommet 51. Through the control slide 5 and the actuating rod 54, the return spring 6 pulls the cable 39 in the direction of the valve housing 4. On further clockwise pivoting of the manually actuated lever 34, the latching pawl 65 then latches in the detent notch 60. Simultaneousiy, the control slide 5 takes up the position IV within the valve housing so that the pump 8 is connected through the blocking unit 14 to the line 16. Thus, the jib 21 is raised.The latching pawl 65 retains the segment 33 in the pivotal position it has reached until, by a sufficiently large force on the manually actuated lever, the latching pawl 65 is forced out of the detent notch 60 or until, by pressure on the pushbutton 71, the electromagnet 75 pivots the latching pawl 65 out of the detent notch 60. As soon as the latching pawl 65 is located outside the detent notch 60, the segment 33 is moved by the resetting unit 36 into the neutral position by releasing the manually actuated lever 34. By pivoting the manually actuated lever 34 anticlockwise, once again out of the neutral position Ill, the latching pawl 65 finally latches in the detent notch 61 which is associated with the position II.In so doing, the rod 42 is pushed towards the right and through the cable 39 pulls the control slide 5 into the position Il against the force of the return spring 6. Moving the control slide 5 in the described manner produces a lowering of the jib 21. The control slide 55 is also movable out of the said position back into the neutral position Ill in the manner already described. If the manually actuated lever 34 is pivoted anticlockwise further out of the described position II, then the latching pawl 65 arrives in the detent notch 62 and the control slide 5 arrives in its position I, the so-called free movement position. From this free movement position, the control slide 5 is also movable once again into its neutral position Ill in the previously described manner.In the case where the cable 39 ruptures when the control slide 5 is located in or between any of the described positions I to IV, the return spring 6 brings the control slide 5 rapidly towards the right into position V. This position V is the emergency switching off position already described with the aid of Figure 2. The control slide 5 moved into the said emergency switching off positions stops the hydraulic drive 18.

The switches 25 and 26 serve as limit position switches and are actuated by the control cam 24 when the jib 21 reaches its constructively predetermined limit positions or its limit positions preselected for the particular application. Like the switch 74, the switches 25 and 26 are connected to the electromagnet 75. Through the control cam 24 and the switches 25, 26, the hydraulic drive 18 can actuate the unlatching device 70 automatically and cause the control slide 5 to be moved back into its neutral position Ill. In the same manner, the unlatching device 70 can control, through the pressure switch 13, an inadmissible pressure rise in the lines 7 and 1 2 which is the result, for example, of an overloading of the jib 21.

The blocking unit 14 inserted between the control valve 2 and the lines 1 6 and 1 7 protects the hydraulic drive 1 8 against so-called cavitation in known manner. Its electromagnets 1 5 serve for unblocking. The electromagnets 1 5 are connected to a switch 78 which is accommodated within the housing 30. A switching cam 79 is arranged on the segment 33, which actuates the switch 78 when the manually actuated lever 34 is located in its neutral position Ill. Thus, the switch 78 is always actuated without any special operation by an operator when the control slide 5 reaches its neutral position lil. The electromagnets 1 5 are connected to a current supply unit 80 which also serves to supply the electromagnet 75.

A rotary valve could also be used instead of a linearly displaceable control slide 5. The concept of the invention may also be accomplished with such control valves provided with valve seats in which the movable valve elements are actuated by control cams or the like.

Instead of the switch 74, a control cam or the like (not shown) can, for example, be movably arranged on the segment 33 in such a manner that it can be pushed by means of the pushbutton 71 and the push rod 73 against the latching pawl 65 or the latching member 64. The pushbutton 71 can be replaced by an actuating lever or a tubular handle mounted for displacement on the lever 34.

Claims

1. A control valve comprising a control member movable into a plurality of switching positions for selectively controlling an hydraulic drive and comprising a mechanical remote control device acting on the control member which has an actuating member, a latching mechanism comprising a latching member loaded by a latching spring and coupled to the actuating member, as well as a resetting device having at least one resetting spring loading the actuating member in the direction of its neutral position, furthermore a tension means arranged between the actuating member and the control member and a return spring arranged in the vicinity of the control member and retaining the tension means permanently under tension, characterised in that, the control member of the control'valve is movable by the return spring into an emergency switching position which, in the operative direction of the return spring, is adjacent to the switching positions which are designed for controlling the drive in alternate driving directions.

2. A control valve according to claim 1 characterised in that the control valve and its control member are designed in such a manner that the control member produces the same switching off effect as in the neutral position when it is located in its emergency switching position.

3. A control valve according to claim 1 or 2 characterised in that the actuating member is formed as a pivotably mounted manually actuated lever.

4. A control valve according to one of claims 1 to 3 characterised in that a device for unlatching the latching member of the latching mechanism is associated with the manually actuated lever.

5. A control valve according to one of claims 1 to 4 characterised in that the device for unlatching has a manually actuable switch and an electromagnet controlled by the said switch and that the electromagnet is associated with the latching member acting oppositely to the latching spring.

6. A control valve according to one of claims 1 to 4 characterised in that the device for unlatching the latching member has a manually actuable actuating means associated with the manually actuated lever and which acts on the latching member against the action of the latching spring through a mechanical member.

7. A control valve according to one of claims 1 to 6 characterised in that the actuating means is designed as a pushbutton displaceably mounted on the manually actuated lever.

8. A control valve according to claims 6 and 7 characterised in that a control cam displaceable towards the latching member by means of the pushbutton and engaging the latching member is mounted on the segment.

9. A control valve according to one of claims 1 to 8 characterised in that at least one pressure switch which controls the electromagnet of the unlatching device is connected to at least one pressure line connected to the control valve.

10. A control valve according to one of claims 1 to 9 characterised in that at least one switch directly or indirectly controllable by the hydraulic drive is provided which controls the electromagnet of the unlatching device.

11. A control valve according to one of claims 1 to 10 characterised in that an electromagneticaliy actuable blocking unit is arranged after the control valve.

12. A control valve substantially as herein described with reference to the accompanying drawings.