GB2111250A

GB2111250A - Apparatus for the control of pressure medium

Info

Publication number: GB2111250A
Application number: GB08232612A
Authority: GB
Inventors: Uwe Altmann; Heinz Walter
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1981-11-17
Filing date: 1982-11-15
Publication date: 1983-06-29
Also published as: FR2516608A1; GB2111250B; FR2516608B1; DE3145525A1

Abstract

A pressure medium is supplied to two parallel connected loads (35, 49) by a pump (10), driven by a pulse controlled electric motor (11), through a control valve (14). The control valve comprises an electro-magnetically actuable proportional valve (15), two pressure maintaining valves (16, 17) and an electro-magnetically actuable multi-way valve (18) which serves for controlling the pressure maintaining valve (16). For actuating the load or loads, the multi-way valve (18) is activated and the control valve (14) then acts as a three-way proportional flow regulating valve. When relieving the load, the pressure maintaining valve (16) is put out of action whereupon the control valve (14) operates as a two-way proportional flow regulator. The valves are controlled by an electronic control apparatus (60) which is controlled by an electric remote adjuster (61). The co-operation of the control valve (14) and the pulse controlled electric motor (11) produce an energy-saving load control, the volume flow is optionally selectable and independent of pressure variations, the loads can be switched completely shock-free. <IMAGE>

Description

SPECIFICATION Apparatus for the control of pressure medium State of the Art The invention originates from an apparatus according to the preamble to the main claim. With such a known apparatus it is necessary to associate with each load its own throttle means, for example in the form of a n e I e an electro-magnetically actuable proportional valve. This increases the cost of the apparatus considerably since such valves are expensive and complicated.

Advantages of the Invention As opposed to this, the apparatus in accordance with the invention comprising the characterising features of the main claim has the advantage that it is simpler as regards the use of apparatus and that the energy required for operating the apparatus is reduced. It is of particular advantage that, by the combination of the valves, a three-way flow regulation of the pressure medium in the direction of one of the loads, during relief thereof a two-way flow regulation, is achieved which is especially achieved for the energy saving control in association with a pulse controlled electric motor.

Advantageous further developments and improvements of the features set forth in the main claim are made possible by the measures set forth in the sub claims.

Drawing An embodiment of the invention is illustrated in the drawing and is explained in detail in the following description. Figure 1 shows a first embodiment of a pressure medium control apparatus in diagrammatic representation, a modification of the embodiment according to Figure 1 is shown in Figure 2.

Description of the Embodiment In Figure 1 a pump which is driven by a pulse controlled electric motor 11 is referenced 10. it draws pressure medium from a reservoir 13 and delivers it into a line 12 which leads to a control valve 14 which consists of the following individual valves: an electromagnetically actuated proportional valve 15, a pressure maintaining valve 1 6 connected in parallel therewith, a pressure maintaining valve 1 7 connected in series with the first valve 16, a four/two-way valve 1 8 as well as a pressure limiting valve 1 9. The proportional valve 1 5 is actuated by a proportional magnet 20 and has a displacement receiver 21; the multi-way valve 1 8 is actuated by an electromagnet 22.

A line 24 which leads through the pressure limiting valve to the reservoir 13 branches from the line 12. Further on, a line 25 which leads to the inlet to the pressure maintaining valve 1 6 branches from the line 12. A branch line 26 from the line 25 leads to the proportional valve 1 5. A control line 12- leads, as a continuation of the line 12, to one end of the pressure maintaining valve 1 7 whereas a line 27 proceeds from its opposite end from which a branch line 27- leads to the proportional valve 1 5. A control line 28 proceeding from the line 27 leads to the multiway valve 18. From the latter, a control line 29 leads to the rear portion of the pressure maintaining valve 16, that is to say it issues at the opposite end to the line 25.The pressure maintaining valve 1 6 has an area ratio of substantially 1:1 and is loaded by a spring 30 away from the end where the control line 29 issues. The pressure maintaining valve 16 is connected to the return line 24.

A line 32, from which a line 33 then proceeds which leads to the proportional valve 15, branches from the line 27. From the pressure maintaining valve 1 7 a line 34 proceeds which leads to a working cylinder 35. Two non-return valves 37, 38, which are electromagnetically actuable, are connected in series in front of the working cylinder. The non-return valve 38 has an electro magnet 39, the non-return valve 37 has an electro-magnet 40. In the position A the nonreturn valves provide a through flow, in the position B they act as non-return valves but in the opposite sense. Beneath the working cylinder, a return line 42 branches from the line 34-. A manually actuated stop-cock 43 is arranged therein.

The pressure maintaining valve 17 is loaded by a spring 44 which is located in the rear portion of the valve. It has transverse bores 45 which issue into the hollow interior thereof. A further comprehensive description of the valves 1 6, 1 7 is omitted since it is readily apparent. The area ratio of the two end surfaces is the same as in the pressure maintaining valve 16, 1:1.

The line 32- leads to a four/three-way valve 48 which is associated with a reversible hydraulic motor 49. From the multi-way valve 48 two lines 50, 51 proceed through non-return valves 52, 53 to the respective inlet and outlet of the hydraulic motor. From the multi-way valve 48 a return line 54 extends to the reservoir 1 3. The multi-way valve 48 is actuated by two electro-magnets 55, 56 and has three switching positions A, B and C. A further four/three-way valve 57 for a third load can be connected to the line 32- or further multi-way valves for further loads. The latter are connected in series but in parallel with the load or working cylinder 35.

All the electro-magnets for the above described valves and the displacement receiver 21 of the proportional valve 1 5 are controlled by an electronic control apparatus 60, the latter is then controlled by a remote adjusting device 61. There, two actuating levers 62, 63 are arranged which are in operative association with desired value generators 64, 65. From there, signals are transmitted through a quantity shaper 66 (for example full wave rectifier), and a logic circuit 67 to two ramp shapers 68, 69 which form therefrom a signal with a definitely positive or negative slope. The magnet 20 of the proportional valve 1 5 is controlled by an amplifier 70 and the electric motor 11 is controlled by an amplifier 71 and a pulse generator 72.The adjustment of the proportional valve is likewise transferred to the control apparatus 60 by the displacement receiver 21.

The electrical output signal from the ramp shaper 68 is also transmitted to a switching amplifier 73 by which the electro-magnets of the described non-return valves are energized. The multi-way valve 48 is adjusted by the electromagnets 55, 56; in that way the direction of the volume of flow to the hydraulic motor is clearly established.

The control of the electrical apparatus for the various hydraulic components is laid down according to a predetermined sequence. First of all, the non-return valves 37, 38 or 55, 56 are operated, then the pulse controlled electric motor and only then the proportional valve 1 5. The switching over of the valves 37, 38 or 55, 56 takes place at zero volume flow; in that way, a shock-free acceleration of the load is possible. It is important that the volume flow from the pump 10 is greater than the set volume flow of the regulating valve 14. Thereby it is ensured that even at low speeds of the pump a safe pressure medium supply for the load is guaranteed.

In order to extend the working cylinder 35, the magnet 39 is first of all actuated whereafter the multi-way valve 38 changes into the through flow position A. Then the magnet 22 is actuated whereupon the multi-way valve 1 8 likewise moves into position A. Thereafter, the electric motor is switched in whereupon the pump begins to deliver pressure medium into the line 12. Only then is the magnet 20 operated and the throttle valve 1 5 arrives from the blocking position B in the through flow position A to a greater or lesser extent as prescribed by the actuating lever 62.

Pressure medium then flows through the throttle valve 1 5 into the line 33 and from there to the pressure maintaining valve 17. This remains in its lower position since pressure medium arrives through the control line 12- under delivery pressure into the chamber receiving the spring and retains the pressure maintaining valve in that position. Also, the pressure maintaining valve 1 6 remains temporarily in its closed position since pressure medium arrives through the lines 27-, 28 and the multi-way valve located in the switching position A as well as the control line 29 at the spring end 30 of the pressure maintaining valve 16. In so doing, no pressure medium can flow out of the line 25 to the reservoir temporariiy.

Thus, the pressure medium delivered by the pump then arrives through the non-return valve 38 located in the through flow position A and the non-return valve 37 to the working cylinder 35 the piston of which is then extended. If this is to be maintained in the said position for a long time then the electric motor 11 is switched off. In view of the non-return valve 37, no pressure medium can flow away from the working cylinder as long as the stopcock 43 is closed. When the pressure in the line 25 is higher than that in the line 29, the pressure maintaining valve 1 6 permits excess pressure medium delivered by the pump to flow into the return line 24.From that it can be appreciated that the control valve 14 in the position "extension" of the working cylinder 35 operates as a three-way flow regulating valve and of course also during actuation of the hydraulic motor 49.

Then, the electro-magnet 40 is energized for lowering the working cylinder 35. The non-return valve 37 moves into the switching position A, the non-return valve 38 is in the position B. Since the pump is not working, only atmospheric pressure prevails in the line 12- and the pressure maintaining valve 1 7 is located in the fully open position illustrated in the drawing. The pressure medium then flows through the pressure maintaining valve 17 into the lines 27 and 32. The pressure then building up in the line 27 closes the pressure maintaining valve against the force of the spring 44. The electro-magnet 20 of the proportional valve 1 5 is then actuated so that the pressure medium can flow from the line 33 through the proportional valve 1 5 into the line 26, 25.Then the pressure in the line 27 and the pressure maintaining valve 1 7 collapses so that the spring 44 and the pressure in the line 12opens the pressure maintaining valve. Then pressure quickly builds up in the pressure maintaining valve once again and it closes once again. This procedure is then repeated continuously. This is because the pressure maintaining valve 1 6 is fully open since its spring chamber is relieved by the multi-way valve 1 8 located in the position B. The pressure medium flowing away from the working cylinder 35 then arrives in the reservoir 1 3. As a result of the force of the spring 30 a lower pressure prevails in the line 25. The proportional valve likewise generates a predetermined throttle resistance.From this it will be appreciated that the control valve 14 operates as a two-way flow regulating valve in the operating condition "lowering" since the pressure maintaining valve 1 7 guarantees a regulated pressure medium discharge.

The electric motor 11 is pulse controlled in accordance with requirements. Thereby and through the construction of the control valve 14 in the form of a two or three-way flow regulating valve, an energy-saving control of the pressure medium is achieved and indeed by saving in primary energy and reducing energy losses. A further advantage consists in the fact that the control valve 14 maintains the volume flow constant independently of pressure variations. The setting of very small volume flows is possible.

Acceleration shocks are prevented by the described circuitry of the multi-way valve.

For actuating the hydraulic motor - according to the sense of rotation -- either the electromagnet 55 or the electro-magnet 56 is energized, likewise the electro-magnet 22 once again whereupon the pressure maintaining valve 1 6 moves into the closed position -- as described above. Only then is the electric motor 11 switched on and the proportional valve 1 5 brought into the desired position corresponding to the desired volume flow by actuating the hand lever 62. Then, pressure medium can once again flow through the proportional valve 1 5 into the bore 32 and from there - when the cylinder is not to be actuated - through the multi-way valve 48 and according to its position either to one or the other input to the hydraulic motor 49.If the pressure medium arrives at the hydraulic motor in the position A of the multi-way valve 48 and through the non-return valve 52, then the non-return valve 53 is closed and vice versa. The pressure maintaining valve 1 7 is likewise located once again in the open position but it can supply no pressure medium to the working cylinder 35 since the non-return valve 38 is located in the blocking position B. Excess pressure medium delivered by the pump can then flow away to the reservoir once again through the activated pressure maintaining valve 1 6.

The desired volume flows are pre-selected by operating the levers 62, 63 to a greater or lesser extent. If, for any reason, the non-return valve 37 should no longer be actuable, then the pressure medium existing in the working cylinder can be discharged through the manually actuated stopcock 43.

The embodiment according to Figure 2 differs from the previous embodiment simply by the fact that the multi-way valves 48, 57 - now provided with an index - are not actuable electrically but manually. However, it is also necessary - in order to achieve the previously described energy-saving control - for the position of these valves to be signalled to the electronic control apparatus. This takes place through the displacement receivers 75, 76. The non-return valves 52, 53 are arranged somewhat differently but act in exactly the same manner. Some variations are made to the electronic control apparatus -- now referenced 77. Only one actuating lever 62 is provided for both the proportional valve 1 5 and for the electric motor 11.

The lines illustrated in the drawing can, of course, also be bores in a housing.

It is preferable to connect to the line 12 a second line 12-- leading to the proportional valve 1 5. In that way, the through flow rate can be doubled. Such a measure is known per se.

Any other electro-magnetically controllable valve can take the part of the proportional valve 15, for example a servo valve.

Claims

1. Apparatus for the pressure medium control of a pump driven by an electric motor to at least one load through throttle means (15) controlled by an electric control apparatus, characterised in that, the throttle means is an adjustable throttle valve (1 5) with which are associated two pressure maintaining valves (16, 17), one of which is in series and the other in parallel and that the parallel connected pressure maintaining valve (16) is actuable by means of a multi-way valve (18) which can be operated at will.

2. Apparatus according to claim 1, characterised in that, the throttle valve is an electro-magnetically actuable proportional valve and that two parallel connected loads (35, 49) are connected to the pump (10).

3. Apparatus according to claim 1 and/or 2, characterised in that, the throttle valve (15), the two pressure maintaining valves (16, 17) as well as the multi-way valve (18) form a control valve (14) which operates as a three-way flow regulating valve for actuating the load but as a two-way flow regulating valve for relieving the load.

4. Apparatus according to one of claims 1 to 3, characterised in that, a first load (35) is formed as a working cylinder with which are associated two series connected electro-magnetically actuable control valves (37, 38) for retracting and extending, and that the second load is an hydraulic motor (49) connected in parallel with the first load and with which is associated a multi-way control valve (48).

5. Apparatus according to one of claims 1 to 4, characterised in that, the control valves and the throttle valve are actuable electro-magnetically.

6. Apparatus according to one of claims 1 to 5, characterised in that, the control of the valves takes place through an electronic control apparatus (60, 77) which is preferably in operative association with an electric remote actuating device (61,78).

7. Apparatus according to one of claims 1 to 6, characterised in that, the electric motor (11) is pulse controlled by the electronic control apparatus and that an electric displacement receiver (21) is associated with the throttle valve (35) and signals the position of the throttle valve to the electronic control apparatus.

8. Apparatus according to one of claims 1 to 7, characterised in that, the two control valves (37, 38) associated with the working cylinder (35) are actuable electro-magnetically and are likewise controllable by the electronic control apparatus.

9. Apparatus according to one of claims 1 to 8, characterised in that, the multi-way control valve (48) for the hydraulic motor (49) is actuable electro-magnetically and is likewise controlled from the electronic control apparatus.

10. Apparatus according to one of claims 1 to 9, characterised in that, the pressure maintaining valves (1 6, 1 7) of the control valve (14) are spring loaded and hydraulically controlled and have an effective area ratio of substantially 1:1.

11. Apparatus according to one of claims 1 to 10, characterised in that, the branch line for the various loads (35, 49) lies down-stream of the throttle valve (15) and the loads are connected in parallel therewith.

12. Apparatus according to one of claims 1 to 11, characterised in that, the electronic control apparatus (60) has a quantity shaper (6) controlled by the remote adjustment device (61), is connected beyond a logic circuit (67) to which are connected one or two ramp shapers (68, 69) beyond which are connected amplifiers or a pulse generator (72) for the electric motor.

13. Apparatus according to one of claims 1 to 12, characterised in that, the pressure maintaining valve (16) can also act as a relief valve.

14. Apparatus according to one of claims 1 to 13, characterised in that, the delivery rate of the pump (10) is slightly higher than the through flow rate set at the throttle means (1 5).

1 5. Apparatus according to one of claims 1 to 14, characterised in that, the valves (37. 38: 48, 57) are appropriately controlled before the control of the electric motor (11) and of the throttle means (15).

1 6. Apparatus for the control of pressure medium substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying drawings.