DE2326737A1 - HYDRAULIC SYSTEM - Google Patents

Description

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Patent and
Utility model registration

ROBERT BOSCH GMBH, STUTTGART

Hydraulic system

The invention relates to a hydraulic system with a pump, a consumer supplied by this and a Control valve, which is arranged between the pump and consumer.

In such hydraulic systems it happens that pumps are loaded at low speeds, for example at idle speeds of an internal combustion engine. As gear pumps trained pumps are particularly vulnerable as they have in this T, el astn.ngsfoll only ei re short life.

it is an object of the invention to make an arrangement with which it is avoided., sensitive pumps at low Load speeds.

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This is achieved according to the invention in that 'the between the pump and the control valve a three-way flow control valve is arranged through which up to the minimum speed of the pump, below which it cannot be loaded, the entire amount of pressure medium it delivers to a pressureless space is, while at higher speeds, all of the pressure medium delivered by the pump to the control valve or consumer flows.

This ensures that the pump cannot deliver any pressure medium to the consumer at low speeds. This is rather branched off from the flow control valve to the container beforehand. Only when the area is more dangerous, lower Speed is exceeded, pressure medium is controlled to the consumer and thus the pump is loaded »

Appropriately, this dangerous area is bypassed by that the constant amount of pressure medium by appropriately dimensioning the spring and the diaphragm for the control slide of the flow control valve is achieved. The flow control valve itself is basically of a known type.

An embodiment of the invention is shown in the drawing. This shows in

Fig. ^Λ a hydraulic system, shown schematically $ Fig. 2 a longitudinal section through a flow control valve »

In Fig. 1, a pump, in particular a gear pump, is designated by IO. This sucks pressure medium from a container '' 2 via a suction line. From the pump Ό leads · -! "A Lruckle: lur. ~ 13 to a three-way ßtromregeüventil" 4-. This is in iir. shown in detail. Two lines "5"'-6 ^to an arbitrarily adjustable three-way valve ^ 7 · lead this the flow control valve 14 can be adjusted, for example manually or electromagnetically. From the three-way valve 17 3 performs a line ^Λ via a throttle ^ 9 to a simple THAT CONDITION riden comparison

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consumers 20, "To 19 around a line leads 21, which is on both sides ^ 9 is connected to the throttle to the line" ¹ S "In the conduit 21 a non-return valve j is disposed 22 to open the throttle in the direction from the directional valve towards the consumer able «

From the line "5, a line 23 leads back 2ο to the container ^Λ Further leads from the line 15 a line 24 via a branch line 24 'to a pressure limiting valve 25" This is relieved to a line 26 by the line ^"1 O branches off and led to a switchover valve 27. This itself is relieved to line 24- _o The pressure relief valve 25 is connected via a control line 28 to a power branch 26 "which leads to line 26" From line 26, a control line 26 "leads to the three-way valve ^ 7s> from which it continues and emptied into line "5" From control line 26, two control lines 27 ° and 27 "lead to switchover valve 27"

The three-way valve 17 has three positions I to III "In the switching position II, all line connections of the pump are _s closed to the consumer during III wherein * switching position pressure medium to the consumer 20 via a branch line 29 with nonreturn valve 29 flows" in the Sehaltstellung I Pressure medium, on the other hand, from the consumer to the container <,

The flow control valve " ¹ A- has a housing 509 in which a slide _{bore 3 ^ is formed 9} the connection to an inlet bore 32 hato An ^{outlet bore 53 connects to the slide bore 3 ^ 1} , to which the line 16 is connected c

A control slide 34 slides tightly in the slide bore 31 led »It has a central recess 35? ^ i e at hers the side facing the inlet bore 32 narrows to a diaphragm 36 is. Located approximately in the middle of the slide hole

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an annular groove 37 ₅ from which a channel 38 leads to a second outlet bore 39. Line ^ 5 is connected to this. A plurality of radial bores 41, which interact with the annular groove 37, are formed in the wall 40 of the control slide. A regulator spring 42, the spring constant of which is relatively small, acts on the control slide 34.

The stroke control valve described above is of known type. The size of the spring constant, which is essentially important, is discussed further below.

The pump 10 in the exemplary embodiment is driven by a motor 43, for example an electric motor or an internal combustion engine. In the low speed range, that is, below the minimum speed of the pump " ¹ O, this should not be loaded, since this will affect its service life. Below this minimum speed, the pump delivers only a small pressure medium flow to the flow control valve 14; The spring 42 of the flow control valve and the orifice 36 are designed so that below this minimum speed the entire flow of the pump flows back to the container via the redial bores 4 "and the lines 15-23. The consumer 20 does not receive any pressure medium, the pump is not loaded as a result. The control slide 3 ^ remains in its end position shown in FIG. Only when the speed of the pump increases does such a large pressure difference arise at the diaphragm 36 that the control slide is displaced against the force of the spring 42. The radial bores 4i then block the connection to the channel 38 and to the outlet bore. No pressure medium can now flow back to the container, rather it now flows to the outlet bore 33 and via the line 16 to the directional control valve 17 · If this is in its switching position III, pressure medium flows via the line to the consumer 20 and actuates it. The pump "0 is now loaded by the pressure created by the resistance of the consumer

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20 is generated. From the above it can be seen that the spring 42 and the diaphragm are designed so that after the minimum speed of the pump is exceeded, the control slide 34 quickly moves into its second control position brought v / ird. The leather constant is Therefore, to choose as small as possible, so that the pressure difference at the Moßdrossel 36 increases as the delivery rate increases increases so that the spring force is quickly overcome. This is so designed that it is at a speed at which the pump must not be loaded, the control spool holds in its first starting position. The aperture 36 has a relatively large one Diameter. It should also be noted that the system does not have any leakage current above the minimum speed of the pump, since then all pressure medium flows to the consumer. The flow control valve thus also has the function of a so-called. Changeover valve, which from a certain delivery rate the entire pressure medium leads to another place.

If the speed of the pump falls below this critical point, the control slide moves from its working position in which the radial bores 4 ^ are separated from the annular groove 37, back to its first starting position, whereupon all pressure medium flows back to the container. The one operating the motor 43 Person is thus forced to keep the speed of the pump during the consumer load always over its critical Keep speed.

If the consumer is to be relieved, the directional valve ^Λ 7 is brought into its holding position I, whereupon pressure medium flows back to the container. The throttle "9 prevents this pressure medium from flowing back too quickly. The pressure-limiting valve and the switchover valve 2" ensure in a known manner that no inadmissibly high pressure arises in the consumer lines.

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Claims (4)

- 6 - E. 1 4 8 β Expectations ί1J Hydraulic system with one pump, one of which is supplied Consumer and a control valve, which is arranged between the pump and consumer, characterized in that, that between the pump ("O) and the control valve (17) a three-way flow control valve (14) is arranged through which to at the minimum speed of the pump, below which it cannot be loaded, the entire amount of pressure medium it delivers is directed to a pressureless space, while at higher speeds all the pressure medium delivered by the pump flows to the control valve or consumer (20). 2. Plant according to claim ", characterized in that the constant amount of pressure medium by appropriately dimensioning the spring (42) and the diaphragm (36) of the control slide (34) of the flow control valve (i4) is achieved. 3. Plant according to claim 1 and / or 2, characterized in that that the flow control valve ("4), as known per se, has a control slide (34) loaded by a leather (42), which has a measuring orifice (36) on its part facing the inlet (32) so that the control slide is hollow and that from the cavity (35) at least one radial bore (4 ") extends to an outlet (39) for the constant 409851/0053 14 8 6 Pressure medium flow connection and that a second outlet (33) is formed, the connection to the consumer (20) has. 4 ·. System according to one of claims ^Λ to 3? characterized in that the spring (42) of the control slide has a flat spring characteristic and that the flow cross-section of the diaphragm (36) is relatively large. 4 0 9 8 5 1 /