DK2771134T3

DK2771134T3 - Pressure Washer

Info

Publication number: DK2771134T3
Application number: DK11776190.8T
Authority: DK
Inventors: Jürgen Klöpfer; Markus Fischer
Original assignee: Kaercher Gmbh & Co Kg Alfred
Priority date: 2011-10-28
Filing date: 2011-10-28
Publication date: 2016-06-06
Also published as: AU2011379616B2; BR112014009619A2; CN103889601B; CN103889601A; WO2013060386A1; EP2771134A1; EP2771134B1; AU2011379616A1

Description

The invention relates to a high-pressure cleaning appliance with an electric motor and a pump, the pump comprising at least one pump chamber, into which at least one piston which is movable back and forth plunges, and which is connected via an inlet valve to a suction line and via an outlet valve to a pressure line, and the pump comprising a first bypass line, via which the pressure line is connected to the suction line, and in which a first overflow valve is arranged, a closing body of the first overflow valve being automatically movable back and forth between a closed position closing the first bypass line and an open position opening the first bypass line in dependence upon a state quantity of a cleaning liquid flowing through the pressure line, and the electric motor being automatically switchable on and off in dependence upon the flow rate of the cleaning liquid flowing through the pressure line.

Such high-pressure cleaning appliances are known from the publication DE 10 2009 049 096 Al. By means of these, a cleaning liquid, for example, water can be pressurized and then directed at an object, for example, via a pressure hose connectable to the pressure line and a nozzle head arranged at the free end of the pressure hose. The nozzle head, for example, a spray gun can be opened and closed manually by the user. When the nozzle head is closed, the cleaning liquid conveyed by the pump can be recirculated, i.e., it can be conducted from the pressure line back to the suction line again. The pressure in the pressure line can thereby be reduced and the mechanical load on the pump lessened. To achieve recirculating operation when the nozzle head is closed, the pressure line is connected to the suction line via a first bypass line, and a first overflow valve is arranged in the first bypass line.

When the nozzle head is open, the cleaning liquid conveyed by the pump flows through the pressure line. A closing body of the first overflow valve thereby automatically transfers to its closed position and so the flow connection between the pressure line and the suction line via the first bypass line is interrupted. If the nozzle head is closed, then no more cleaning liquid can flow through the pressure line. This causes the closing body of the first overflow valve to automatically assume its open position. The first overflow valve thereby opens the flow connection between the pressure line and the suction line via the first bypass line, and so the cleaning liquid can be recirculated. If the nozzle head is then opened again, the cleaning liquid flows through the pressure line again and the closing body of the first overflow valve automatically assumes its closed position, and so the flow connection between the pressure line and the suction line via the first bypass line is interrupted again. The transfer of the first overflow valve thus occurs in dependence upon the cleaning liquid flowing through the pressure line. The flow rate of the cleaning liquid serves as state quantity.

The closing body of the first overflow valve may, for example, be controlled by means of a control member which is connected to the closing body of the first overflow valve and displaces the closing body to its closed position or its open position in dependence upon the state quantity of the cleaning liquid flowing through the pressure line.

In order to reduce the energy consumption of the high-pressure cleaning appliance when the nozzle head is closed, the electric motor, which drives the pump, is automatically switchable on and off in dependence upon the flow rate of the cleaning liquid flowing through the pressure line. To this end, the closing body of the first overflow valve in the pump known from DE 10 2009 049 096 A1 is rigidly connected to a switching plunger which actuates a switching element for switching on and off the pump. It is possible to activate and deactivate the electric motor and, by means of the latter, the pump by actuating the switching plunger. When the flow of liquid in the pressure line of the pump is interrupted by the nozzle head arranged at the free end of the pressure hose being closed, this results, firstly, in the first overflow valve opening the flow connection between the pressure line and the suction line via the first bypass line and in the pressure prevailing in the pressure line thereby being reduced. Secondly, the switching plunger is thereby displaced to a first switching position, and so the switching element in operative connection with it switches off the electric motor. If the nozzle head is opened again, any liquid in the pressure line and in the pressure hose can exit via the nozzle head. The related flow of liquid in the pressure line results in the first overflow valve assuming its closed position again and in the electric motor being activated again.

The object of the present invention is to further develop a high-pressure cleaning appliance of the generic kind such that its energy consumption can be further reduced.

This object is accomplished, in accordance with the invention, in a high-pressure cleaning appliance of the kind mentioned at the outset in that the pump comprises a second bypass line, which leads from the pressure line to the suction line, and in which is arranged a second overflow valve whose closing body is manually movable between a closed position closing the second bypass line and an open position opening the second bypass line.

The pump therefore has two bypass lines which each enable a flow connection from the pressure line to the suction line and in each of which an overflow valve is arranged. The overflow valve arranged in the first bypass line opens and closes in dependence upon a state quantity of the cleaning liquid flowing though the pressure line, for example, in dependence upon the pressure or upon the flow rate of the cleaning liquid. The first overflow valve may, for example, open the first bypass line once the flow rate of the cleaning liquid flowing through the pressure line falls below a lower limit value, and it can block the first bypass line once the flow rate of the cleaning liquid flowing through the pressure line exceeds a predetermined maximum value. Here the closing body of the first overflow valve can be coupled to a first switching element for switching on and off the pump, and so the pump can be automatically switched off once the flow rate of the cleaning liquid flowing through the pressure line falls below the predetermined minimum value. Alternatively, it may be provided that the first overflow valve opens the first bypass line once the pressure of the cleaning liquid in the pressure line exceeds a predetermined maximum value, and the first overflow valve can block the first bypass line when the pressure of the cleaning liquid in the pressure line falls below a predetermined minimum value. Independently of the pressure of the cleaning liquid, the pump can be switched on and off in dependence upon the flow rate of the cleaning liquid, as described hereinabove.

Independently of the state quantity of the cleaning liquid flowing through the pressure line, the user can, if required, manually open and interrupt a second flow connection between the pressure line and the suction line. The second bypass line in which a second overflow valve is arranged is used for this purpose. The closing body of the second overflow valve is manually movable between a closed position closing the second bypass line and an open position opening the second bypass line. During continuous working operation of the pump, the manually actuatable second overflow valve enables the user to conduct some of the conveyed cleaning liquid back from the pressure line via the second bypass line to the suction line. The remaining amount of conveyed cleaning liquid can be discharged via the pressure line and, for example, directed at an object to be cleaned.

The user can therefore automatically select whether he would like to direct at an object the total cleaning liquid that is pressurized by the pump or whether he would like to direct only some of the cleaning liquid conveyed by the pump at the object. The latter may, for example, be the case for objects that are easy to clean and for which some of the cleaning liquid pressurized by the pump is adequate to remove the dirt. In this case, the user can move the closing body of the second overflow valve to its open position and thereby open the flow connection from the pressure line via the second bypass line to the suction line. This, in turn, results in the water consumption of the pump being reduced. In addition, the energy consumption of the pump is also reduced as the pressure in the suction line rises when the closing body of the second overflow valve assumes its open position and pressurized cleaning liquid can flow via the second bypass line to the suction line. Owing to this rise in pressure in the suction line, the consumption of energy which the pump requires for pressurizing the cleaning liquid is lower than when the second overflow valve is closed.

Therefore, what distinguishes the pump in accordance with the invention is that a flow path from the pressure line to the suction line via a first bypass line is opened in dependence upon a state quantity of the cleaning liquid flowing through the pressure line, and that independently of the state quantity of the cleaning liquid flowing through the pressure line, a flow path can be manually provided from the pressure line to the suction line via a second bypass line. This allows the user to selectively direct either 100 % of the cleaning liquid pressurized by the pump via the pressure line or less than 100 % of the cleaning liquid at an object. It is expedient if about one tenth to one third of the cleaning liquid pressurized by the pump can be conducted back to the suction line when the second overflow valve is open.

In particular, it may be provided that when the second overflow valve is open, about 20 % of the cleaning liquid pressurized by the pump is conducted back from the pressure line via the second bypass line to the suction line, i.e., about 20 % of the cleaning liquid pressurized by the pump is recirculated.

The first bypass line forms a first flow path from the pressure line to the suction line. The second bypass line preferably forms a second flow path from the pressure line to the suction line, which is independent of the first flow path.

In order to simplify the handling of the pump, it is advantageous if the pump comprises a manually actuatable actuating device having several actuating positions, the electric motor of the pump being switchable on and off and the second overflow valve being openable and closable by means of the actuating device. In such an embodiment, both the pump can be switched on and off and the flow path from the pressure line to the suction line via the second bypass line can be selectively interrupted and opened by means of a single actuating device. For this purpose, the actuating device has several actuating positions. The actuating device makes it possible for the pump to be switched off or operated in different modes of operation. In a first mode of operation, 100 % of the cleaning liquid pressurized by the pump can be discharged via the pressure line, and the pump can be automatically switched on and off in dependence upon the cleaning liquid flowing through the pressure line, as already explained hereinabove. In a second mode of operation, the pump can also be automatically switched on and off in dependence upon the cleaning liquid flowing through the pressure line, however, in the second mode of operation, some of the cleaning liquid pressurized by the pump is recirculated also when the nozzle head is open, i.e., some of the pressurized cleaning liquid is directly conducted back from the pressure line to the suction line via the second bypass line.

It may be provided that the actuating device comprises an actuating element which is selectively movable back and forth between a first actuating position in which the pump is switched off, a second actuating position in which the pump is switched on and the second overflow valve is closed, and a third actuating position in which the pump is switched on and the second overflow valve is open. The actuating element may, for example, be configured in the manner of a switch which has several switching positions. In the first actuating position, the second overflow valve can be closed.

It is advantageous if the actuating element is configured as a rotary switch.

In an advantageous embodiment of the pump in accordance with the invention, the actuating element comprises a rotatably mounted switching shaft which is coupled to a switching element of the high-pressure cleaning appliance and to the second overflow valve. The switching shaft can be manually rotated about its longitudinal axis by the user. In a first rotational position, the electric motor can be switched off by the switching element, which is coupled to the switching shaft. In this switching position, the second overflow valve can assume its closed position, for example, under the action of a return spring. In a second rotational position, the electric motor can be switched on, with the second overflow valve being closed, and in a third rotational position, the electric motor can be switched on and the second overflow valve can be open. With such a configuration, the handling of the pump is particularly easy.

The switching shaft is preferably directly connected to the switching element of the pump and is coupled via at least one coupling element to the second overflow valve. The switching shaft can therefore form a component of a rotary switch with which the high-pressure cleaning appliance can be manually switched on and off. The switching shaft also serves to actuate the second overflow valve so that it can be manually opened and closed by the user in order to open the flow path via the second bypass line.

The switching shaft can be coupled to the second overflow valve in different ways, for example, by a switching cam which interacts with at least one coupling element in dependence upon the rotational position of the switching shaft being arranged on the switching shaft, a movement of the switching shaft being transferable to the closing body of the second overflow valve via the coupling element. Depending on which rotational position the switching shaft assumes, a movement of the switching shaft can be transferred to the closing body of the second overflow valve. Transfer of the movement occurs via at least one coupling element. This allows the user to rotate the switching shaft, starting from a first rotational position in which the pump is switched off, to a second switching position in which the pump is switched on, with the rotational movement of the switching shaft not being transferred to the closing body of the second overflow valve. Only a rotational movement of the switching shaft from the second rotational position to the third rotational position is transferred via the coupling element to the closing body of the second overflow valve so that the pump remains switched on in the third rotational position of the switching shaft and, at the same time, the flow connection from the pressure line via the second bypass line to the suction line is opened.

Alternatively, the switching shaft can be coupled to the second overflow valve by means of a sliding link which is arranged on the switching shaft and with which a coupling element interacts, a movement of the switching shaft being transferrable to the closing body of the second overflow valve via the coupling element. The sliding link may, for example, be configured in the form of a sleeve which surrounds the switching shaft and has on its outer side a slide surface or groove formed in the manner of the turn of a thread against which a sliding link block lies in a sliding manner, the sliding link block being arranged on a coupling element which transfers the movement of the sliding link block to the closing body of the second overflow valve. If the sliding link which is rigidly connected to the switching shaft is rotated about the longitudinal axis of the switching shaft, the sliding link block executes an axial movement in relation to the longitudinal axis of the switching shaft, and by means of at least one coupling element this axial movement can be transferred to the closing body of the second overflow valve, and so owing to a rotational movement of the switching shaft, the closing body transfers from a closed position to its open position.

It is particularly advantageous if the actuating element of the actuating device is coupled via a swivel lever to the second overflow valve. The swivel lever forms a transducer and so a relatively large force can be exerted on the second overflow valve even when the user only acts upon the actuating element with a relatively low force. The handling of the pump is thereby additionally simplified.

In an advantageous embodiment of the invention, the swivel lever is arranged on an outer side of a pump housing of the pump. This facilitates assembly of the swivel lever.

In an expedient manner, the closing body of the second overflow valve is displaceably mounted, and the swivel lever interacts with the displaceable closing body. The closing body of the second overflow valve can therefore be displaced back and forth between a closed position and an open position. The force required to displace the closing body can be exerted on the closing body by the swivel lever. The swivel lever, in turn, interacts with the actuating element of the actuating device. For example, the swivel lever can lie against a switching cam or a sliding link which is fixed to a switching shaft.

It is particularly advantageous if the swivel lever is pretensioned by means of a spring element in the direction towards the actuating element.

In an expedient manner, the swivel lever is mounted on the pump for swivel movement about a swivel axis. The swivel axis is preferably aligned parallel or perpendicularly to the longitudinal axis of the pistons of the pump.

In a particularly advantageous embodiment of the invention, the swivel lever comprises a long and a short lever arm, the long lever arm lying against the actuating element and the short lever arm acting on the closing body of the second overflow valve. The long lever arm can be at least twice as long as the short lever arm. In particular, it may be provided that the length of the long lever arm is at least four times that of the short lever arm. The greater the difference between the lengths of the two lever arms, the easier it is to act upon the closing body with an actuating force, under the action of which it transfers from its closed position to its open position. In particular, when the closing body is displaceably mounted, it is expedient if the long lever arm is at least four times longer than the short lever arm. A relatively low actuating force can be exerted by the actuating element on the long lever arm, and a multiple of this actuating force can then be exerted by the short lever arm on the closing body of the second overflow valve.

In an advantageous embodiment of the invention, the short lever arm comprises a lever body on which a pressure element which interacts with the closing body is displaceably mounted. When the swivel lever is swivelled, an actuating force can be transferred via the pressure element to the closing body so that it transfers from its closed position to its open position.

The pressure element is preferably adjustable relative to the lever body. Manufacturing and assembly tolerances can thereby be easily compensated.

It is expedient if a pressure spring is clamped between the lever body and the pressure element. The pressure element can thereby be displaced relative to the lever body counter to a spring-elastic reset force. This makes it possible to influence the actuating force exerted by the lever body via the pressure element on the closing body of the second overflow valve by choice of a certain pressure spring, i.e., a pressure spring with a certain spring constant.

It is advantageous if the closing body of the second overflow valve is movable from its closed position to its open position counter to a spring-elastic reset force. The reset force exerted on the closing body can be provided by a return spring of the second overflow valve whose spring constant can be adapted to the spring constant of the pressure spring of the short lever arm. This allows, in a particularly reliable way, an actuating force to be exerted on the closing body of the second overflow valve by swivelling the swivel lever, under the action of which the closing body transfers from its closed position to its open position. With such a configuration, the second overflow valve and, consequently, also the high-pressure cleaning appliance in accordance with the invention are particularly insensitive to faults and are characterized by a particularly long service live.

In a particularly preferred configuration of the invention, the closing body of the second overflow valve, in its closed position, can be acted upon with a closing force by the pressure of the cleaning liquid prevailing in the pressure line. In such a configuration, the pressure of the cleaning liquid prevailing in the pressure line acts in the direction towards the closed position of the closing body of the second overflow valve, and so the closing body can be pressed tightly against a valve seat by the pressure of the cleaning liquid. The transfer of the closing body of the second overflow valve from its closed position to its open position then occurs counter to the action of the pressure exerted by the cleaning liquid. It is thereby ensured in a constructionally simple manner that the closing body of the second overflow valve assumes its closed position if no manual actuating force is exerted on the closing body.

It is advantageous if the closing body of the second overflow valve is movable to its open position by means of a displaceably mounted valve plunger counter to the pressure of the cleaning liquid acting on it in the closed position. The valve plunger can be displaced by the user, for example, by means of the swivel lever explained hereinabove counter to the pressure acting on the closing body, and the valve plunger transfers the closing body to its open position in which the closing body assumes a distance from the valve seat and thereby opens the flow path between the pressure line and the suction line via the second bypass line.

In an advantageous embodiment of the invention, the pump comprises a pump head which is placed on a cylinder block, the cylinder block comprising the at least one pump chamber, and the pump head forming the suction line and the pressure line as well as a first accommodating chamber for the first overflow valve and a second accommodating chamber for the second overflow valve.

The two accommodating chambers are advantageously each of elongate configuration and have longitudinal axes aligned parallel or perpendicularly to each other.

In a particularly preferred configuration of the invention, the longitudinal axes of the accommodating chambers are aligned parallel or perpendicularly to the longitudinal axis of the pressure line of the pump. A particularly simple assembly is achieved in an advantageous configuration of the invention by the two accommodating chambers of the pump head each having a passage which connects the accommodating chambers to an annular channel, the annular channel being arranged between the cylinder block and the pump head. The bypass lines can be connected to the suction line via the annular channel and the passages.

It is advantageous if a check valve is arranged in the second bypass line. The check valve opens in the direction of flow of the cleaning liquid flowing from the pressure line via the second bypass line to the suction line. The check valve facilitates the ventilation of the pump. If there is air in the suction line or in the pump chambers when the pump is started, it must first be discharged by the pump via the pressure line. If the user already opens the second overflow valve when starting the pump, there is the possibility that the air still in the pump will not be discharged to the outside via the pressure line but will be recirculated. To prevent this, use is made, in an advantageous embodiment, of a check valve which is installed in the second bypass line. The check valve is preferably arranged downstream of the second overflow valve. The check valve automatically transfers to its open position provided that cleaning liquid is flowing through the second bypass line, but it remains in its closed position as long as there is only air in the second bypass line. The air can therefore not be recirculated but can be reliably discharged via the pressure line when the pump is started.

The following description of preferred embodiments of the invention serves in conjunction with the drawings for further explanation. There are shown in:

Figure 1 a side view of a first embodiment of a high-pressure cleaning appliance with a pump and an electric motor;

Figure 2 a front view of the high-pressure cleaning appliance from Figure 1;

Figure 3 a partially sectional view of the pump along line 3-3 in Figure 2;

Figure 4 a partially sectional view of the pump along line 4-4 in Figure 2;

Figure 5 a simplified side view of the pump, wherein an actuating element assumes a first actuating position;

Figure 6 a simplified side view of the pump, wherein the actuating element assumes a second actuating position;

Figure 7 a simplified side view of the pump, wherein the actuating element assumes a third actuating position;

Figure 8 a partially sectional view of the pump of a second embodiment of a high-pressure cleaning appliance corresponding to Figure 4;

Figure 9 a perspective representation of a third embodiment of a high-pressure cleaning appliance;

Figure 10 a front view of the high-pressure cleaning appliance from Figure 9; and

Figure 11 a perspective representation of a swivel lever of the high-pressure cleaning appliance shown in Figures 8 and 9. A first embodiment of a high-pressure cleaning appliance 10 in accordance with the invention with a pump 12 and a liquid-cooled electric motor 14 which drives the pump 12 is shown schematically in Figures 1 and 2. The electric motor 14 comprises a motor housing 16 which is of pot-shaped configuration and comprises a cylindrical side wall 17 and a bottom wall 18. The side wall 17 is surrounded by a cooling housing 20. A cooling channel, not shown in the drawings, which surrounds the motor housing 16, is located in the area between the side wall 17 and the cooling housing 20. Cleaning liquid can be fed to the cooling channel via an inlet line 22, and the cleaning liquid can be fed from the cooling channel via an outlet line 24 to a suction inlet 26 of the pump. This makes it possible to first conduct the cleaning liquid to be pressurized by the pump 12 around the motor housing 16 of the electric motor 14 so that waste heat from the electric motor 14 can be conducted away by the cleaning liquid.

The pump 12 comprises a cylinder block 28 and a pump head 30, which is placed on the cylinder block 28 and has a pressure outlet 34 at its front end face 32 facing away from the cylinder block 28. Cleaning liquid pressurized by the pump 12 can be discharged via the pressure outlet 34. A pressure hose, for example, carrying at its free end a nozzle head, for example, a hand spray gun, can be connected to the pressure outlet 34. The pressurized cleaning liquid can be directed at an object via the nozzle head.

An outer sealing ring 36 and an inner sealing ring 38, which are aligned concentrically with each other, are arranged between the pump head 30 and the cylinder block 28. An annular channel 40, which is formed in a rear end face 42 of the pump head 30, is arranged between the outer sealing ring 36 and the inner sealing ring 38. The rear end face 42 is arranged on the side of the pump head 30 that faces away from the front end face 32.

The cylinder block 28 comprises a total of three pump chambers, only one pump chamber 44 being shown in the drawings. A piston plunges into each pump chamber, a first piston 46 and a second piston 48 being recognizable in Figures 5, 6 and 7. All of the pistons are oscillatingly pressed into the respective pump chamber 44 by a swash plate, known per se and not shown in the drawings in order to provide a better overview, and are pressed out of the pump chamber 44 again by a helical spring 50 and 52, respectively, surrounding the respective piston, so that the volume of the pump chambers 44 periodically changes.

Each pump chamber 44 is in flow connection with a suction line 58 via an inlet line 54 which is formed in the cylinder block 28 and in which an inlet valve 56 is installed. The suction line 58 extends from the suction inlet 26 to the annular channel 40 into which the inlet line 54 opens.

Via an outlet line 60 which is formed in the cylinder block 28 and in which an outlet valve 62 is installed, each pump chamber 44 is in flow connection with a pressure line 68 which is aligned parallel to the longitudinal axis 66 of the pistons 46, 48. The pressure line 68 leads to the pressure outlet 34. A central pressure valve 70 is arranged in the pressure line 68, and downstream of the pressure valve 70 the pressure line 68 accommodates a throttle element in the form of an injector 72. This comprises in the usual manner a through-bore 74, which first narrows and then widens again in the direction of flow, with a transverse bore 76 branching off from its narrowest point.

In addition to the suction line 58 and the pressure line 68, a first accommodating chamber 78, shown in Figure 3, and a second accommodating chamber 80, shown in Figure 4, which each extend from the front end face 32 parallel to the longitudinal axis 66 of the pistons 46, 48 to a first chamber bottom 82 and a second chamber bottom 84, respectively, are formed in the pump head 30. The first chamber bottom 82 comprises a first passage 86 and the second chamber bottom 84 comprises a second passage 88. The two passages 86 and 88 connect the first accommodating chamber 78 and the second accommodating chamber 80, respectively, with the annular channel 40.

The first accommodating chamber 78 is closed in the area of the front end face 32 by a plug 90. In the area adjoining the plug 90, the first accommodating chamber 78 defines a control chamber 92 which is adjoined by a lower line section 94 of a bypass line 96 explained in greater detail hereinbelow. The lower line section 94 accommodates a first overflow valve 98 and is in flow connection via the first passage 86 with the annular channel 40 and via the latter with the suction line 58.

The control chamber 92 is of cylindrical configuration and accommodates a slide sleeve in which a control member in the form of a control piston 102 is held so as to be displaceable parallel to the longitudinal axis of the pistons 46, 48. The control piston 102 divides the control chamber 92 into a low-pressure chamber 104 facing the plug 90 and a high-pressure chamber 106 facing away from the plug 90. The lower line section 94 of the first bypass line 96 adjoins the high-pressure chamber 106. A sleeve-shaped valve housing 108 of the first overflow valve 98 is installed in the lower line section 94 of the first bypass line 96. The valve housing 108 defines a valve seat of a closing body 110 of the first overflow valve 98. The closing body 110 forms a conical widening of a switching plunger 112 which is secured to the control piston 102 and passes through the valve housing 108 of the first overflow valve 98. With its free end facing away from the control piston 102, the switching plunger 112 lies against a first switching element 114 which can be actuated by the switching plunger 112. The first switching element 114 is integrated in an electronic control system 116 of the high-pressure cleaning appliance 10. The electronic control system 116 is arranged in a receptacle 118 of the cylinder block 28.

The transverse bore 76 of the injector 72 arranged in the pressure line 68 is in flow connection via a control channel 120 with the low-pressure chamber 104. Upstream of the injector 72 and the central pressure valve 70, an upper line section 122 of the first bypass line 96 extends from the pressure line 68 to the high-pressure chamber 106. The aforementioned lower line section 94 of the first bypass line 96 adjoins the upper line section 122 in the first accommodating chamber 78. The first bypass line 96 defined by the two line sections 122 and 94 forms in combination with the annular channel 40 a flow connection between the pressure line 68 and the suction line 58. The first overflow valve 98 whose closing body 110 selectively interrupts or opens the first bypass line 96 is arranged in the first bypass line 96. The position of the closing body 110 is predetermined by the control piston 102. The position of the control piston 102 is, in turn, dependent upon the flow rate of the cleaning liquid flowing through the pressure line 68. This will be explained in greater detail hereinbelow.

The pump chambers 44 can be supplied with cleaning liquid to be conveyed, which has previously flowed around the motor housing 16 of the electric motor 14 in the circumferential direction, via the suction line 58 and the adjoining inlet lines 54. Owing to the oscillating movement of the pistons, the cleaning liquid is pressurized in the pump chambers 44, and the pressurized cleaning liquid is fed via the outlet lines 60 to the pressure line 68.

During normal operation of the pump 12, the pressurized cleaning liquid flows through the injector 72. This forms in the pressure line 68 a throttle point at which the cleaning liquid flowing through undergoes a dynamic pressure drop and so the area of the pressure line 68 arranged upstream of the injector 72 has a higher pressure than the area of the pressure line 68 at the level of the transverse bore 76 of the injector 72. As long as cleaning liquid is flowing through the pressure line 68, the low-pressure chamber 104 connected via the control channel 120 to the transverse bore 76 is therefore acted upon with a lower pressure than the high-pressure chamber 106 connected via the upper line section 122 of the first bypass line 96 to the inlet area of the pressure line 68. This results in the control piston 102 being displaced in the direction towards the plug 90 so the closing body 110 of the first overflow valve 98 lies tight against the associated valve seat of the valve housing 108, and the flow connection between the pressure line 68 and the suction line 58 via the first bypass line 96 and the annular channel 40 is thereby interrupted. The movement of the control piston 102 in the direction towards the plug 90 is assisted by a pressure spring 124 which is supported, on the one hand, on the control piston 102 and, on the other hand, on the valve housing 108.

If the flow of cleaning liquid through the pressure line 68 is interrupted, for example, by a nozzle head which is connected via a pressure hose to the pressure line 68 being closed, cleaning liquid then no longer flows through the injector 72 and, consequently, there is no dynamic pressure drop in the area of the constriction of the injector 72, and so the pressure in this area is identical to the pressure upstream of the pressure valve 70. In this case, identical pressures occur in the low-pressure chamber 104 and the high- pressure chamber 106, and in accordance with suitable dimensions of the effective pressure surfaces of the control piston 102, the latter is displaced counter to the action of the pressure spring 124 in the direction facing away from the plug 90. This results in the closing body 110 lifting off from its associated valve seat and thereby opening the flow connection from the pressure line 68 via the first bypass line 96 and the ring channel 40 to the suction line 58. The pressure prevailing in the pressure line 68 can therefore drop.

As the switching plunger 112 is rigidly connected to the control piston 102, a movement of the control piston 102 also results in actuation of the first switching element 114. The electric motor 14 can thereby be switched off. Operation of the electric motor 14 while the nozzle head is closed is thereby avoided.

If the nozzle head is then opened again, cleaning liquid can escape from the pressure line 68 via the nozzle head. This results in a flow of liquid forming again in the pressure line 68 and so the pressure in the low-pressure chamber 104 drops and the control piston 102 performs a movement in the direction of the plug 90. The closing body 110 thereby automatically resumes its closed position, and the switching plunger 112 releases the first switching element 114 and so the electronic control system 116 switches the electric motor 14 on again and normal operation of the pump 12 can be continued, with the flow connection between the pressure line 68 and the suction line 58 via the first bypass line 96 and the ring channel 40 being interrupted again.

The second accommodating chamber 80 accommodates a cylindrical valve housing 126 of a second overflow valve 128. The valve housing 126 is surrounded in the circumferential direction by a first sealing ring 130 and a second sealing ring 132 and in the area between the two sealing rings 130, 132 has an annular groove 134 which extends in the circumferential direction and is connected via a radially extending channel 136 to a through-channel 138. The through-channel 138 passes through the valve housing 126 in the longitudinal direction. It comprises a front channel section 140 facing away from the second chamber bottom 84 and a rear channel section 142 facing the second chamber bottom 84. The diameter of the rear channel section 142 is larger than the diameter of the front channel section 140. In the area of transition between the front channel section 140 and the rear channel section 142, the through-channel 138 forms a valve seat. A spherical closing body 146 of the second overflow valve 128, which is pressed by a closing spring 148 against the valve seat, is arranged in the rear channel section 142. The closing spring 148 is supported, on the one hand, on the closing body 146 and, on the other hand, on a supporting body 150 which is arranged between the valve housing 126 and the second chamber bottom 84. A second through-channel 152 which also passes through the valve housing 126 in the longitudinal direction and extends from an end-face depression 154 of the valve housing 126 to a connecting channel 156 of the supporting body 150 runs parallel to the first through-channel 138. The connecting channel 156 forms a flow connection between the second through-channel 152 and the second passage 88 and so the second through-channel 152 is in flow connection with the annular channel 40 via the connecting channel 156 and the second passage 88.

The annular groove 134 is connected to the area of the pressure line 68 upstream of the central pressure valve 70 via a connecting line 158 extending at an incline to the longitudinal axis of the second accommodating chamber 80. A throttle element in the form of an orifice element 159 is installed in the connecting line 158. The connecting line 158 forms in combination with the channel 136, the rear channel section 142, the front channel section 140, the end-face depression 154, the second through-channel 152 and the connecting channel 156 a second bypass line 160 via which the pressure line 68 is in flow connection with the annular channel 40 and via the latter with the suction line 58. The second bypass line 160 can be interrupted and opened by the closing body 146 of the second overflow valve 128.

To open the second bypass line 160, the closing body 146 of the second overflow valve 128 can be acted upon by a valve plunger 162 with a force which opposes the spring force of the closing spring 148 and the pressure of the cleaning liquid in the pressure line 68. The valve plunger 162 is mounted in a guide sleeve 164 so as to be displaceable in the longitudinal direction of the second accommodating chamber 80. The guide sleeve 164 forms an end-face closure of the second accommodating chamber 80 and is surrounded in the circumferential direction by a sealing ring 166 which lies tight against the wall of the second accommodating chamber 80.

To manually open the second overflow valve 128, the pump 12 has an actuating device 168 which is arranged laterally next to a pump housing 170 of the pump 12. The actuating device 168 comprises a switching shaft 172 which is aligned transversely to the longitudinal axis of the pump 12 and is directly connected to a second switching element 174 of the electronic control system 116. By rotating the switching shaft 172 about its longitudinal axis, the electric motor 14 of the high-pressure cleaning appliance 10 can be switched on and off by means of the second switching element 174. As will be clear, in particular, from Figures 5, 6 and 7, a switching cam 176 which interacts with a coupling element in the form of a two-armed swivel lever 178 to open the second overflow valve 128 is held on the switching shaft 172. The swivel lever 178 is mounted laterally on the pump housing 170 for swivel movement about a swivel axis 180 aligned parallel to the longitudinal axis of the switching shaft 172 and comprises a long lever arm 182 which lies with its free end against the switching cam 176, and a short lever arm 184. The long lever arm 182 is about five times longer than the short lever arm 184.

The short lever arm 184 comprises a lever body 186 which has a stepped through-bore, aligned flush with the valve plunger 162, with a first bore section 188 facing away from the valve plunger 162, and a second bore section 190 facing the valve plunger 162. A mushroom-shaped pressure element 192 passes through the through-bore. A pressure head 194 of the pressure element 192 lies against the valve plunger 162, and a pressure shaft 196 of the pressure element 192 extends from the pressure head 194 through the second bore section 190 and the first bore section 188. It protrudes from the first bore section 188 in the direction facing way from the valve plunger 162. In its protruding area, a retaining ring 198 which can be pushed onto the pressure shaft 196 is secured to the outside of the pressure shaft 196. The position of the pressure element 192 relative to the lever body 186 can be adjusted by means of the retaining ring 198. Inside the second bore section 190, the pressure shaft 196 is surrounded by a pressure spring 200 which is supported, on the one hand, on a step 202 arranged between the first bore section 188 and the second bore section 190, and, on the other hand, on the pressure head 194.

As will be clear from Figures 5, 6 and 7, the switching shaft 172 has three switching positions. A first switching position is shown in Figure 5. In this switching position, the electric motor 14 is switched off by means of the second switching element 174, and the switching cam 176 points in the direction facing away from the swivel lever 178. The swivel lever 178 lies directly against the switching shaft 172. This results in the pressure element 192 of the short lever arm 184 assuming a swivelled back position, i.e., a position at the maximum spacing from the guide sleeve 164. In this position, the valve plunger 162 lying against the pressure element 192 does not exert any actuating force on the closing body 146 of the second overflow valve 128. This results in the closing body 146 under the action of the closing spring 148 and owing to the pressure prevailing upstream of the central pressure valve 70 in the pressure line 68 and acting on the closing body 146 via the channel 136 and the connecting line 158 assuming its closed position. The flow connection between the pressure line 68 and the suction line 58 via the second bypass line 160 and the annular channel 40 is therefore interrupted. Starting from its first rotational position shown in Figure 1, the switching shaft 172 can be transferred by rotation through 90° to its second switching position shown in Figure 2. This results in the second switching element 174 of the electronic control system 116 switching on the electric motor 14 and in the pump 12 being driven. As already explained hereinabove, cleaning liquid can then be pressurized and discharged via the pressure line 68. If the flow of cleaning liquid in the pressure line 68 is interrupted by the nozzle head arranged at the free end of the pressure hose being closed, a flow connection between the pressure line 68 and the suction line 58 via the first bypass line 96 and the annular channel 40 is then opened and, at the same time, the electric motor 14 is switched off by means of the first switching element 114. If the flow of cleaning liquid in the pressure line 68 starts again, the electric motor 14 is then automatically switched on again and the flow connection via the first bypass line is interrupted again.

Starting from its second switching position shown in Figure 6, the switching shaft can be transferred by further rotation through 90° to its third switching position which is shown in Figure 7. The transfer from the second switching position to the third switching position has no effect on the second switching element 174, and so the electric motor 14 remains switched on and the pump 12 therefore continues to be driven. In the third switching position, however, the swivel lever 168 is swivelled by the switching cam 176 and so the short lever arm 184 approaches the guide sleeve 164 with its pressure element 192. The valve plunger 162 is thereby moved by the pressure element 192 in the direction towards the closing body 146, and so the closing body 146 lifts off from the valve seat and thereby opens the flow connection between the pressure line 68 and the suction line 58 via the second bypass line 160 and the annular channel 40. This results in some of the cleaning liquid which is pressurized by the pump 12, namely approximately 20 % of the pressurized cleaning liquid, being recirculated, and so only about 80 % of the cleaning liquid pressurized by the pump 12 is discharged via the pressure line 68. If the flow of liquid in the pressure line 68 is interrupted in the third switching position of the switching shaft 172, the electric motor 14 is then automatically switched off in a corresponding manner by means of the first switching element 114, as already explained hereinabove.

The user therefore has the possibility of switching on and off the pump 12 by means of the switching shaft 172. Furthermore, by means of the switching shaft 172 the user can choose whether he wants to discharge 100 % of the pressurized cleaning liquid via the pressure line 68 or whether he would like to recirculate some of the pressurized cleaning liquid. The latter results in the energy consumption of the high-pressure cleaning appliance 10 being reduced. A partially sectional view of a second embodiment of a high-pressure cleaning appliance in accordance with the invention is shown schematically in Figure 8. The second embodiment is substantially identical to the first embodiment explained hereinabove with reference to Figures 1 to 7. The same reference numerals are therefore used in Figure 8 as in Figures 1 to 7 for identical components and, in order to avoid repetitions, reference is made to the above explanations in connection with these components.

In the second embodiment shown in Figure 8, a check valve 210 with a valve ball 212 which forms the closing body of the check valve 210 and is pressed by a valve spring 214 against a valve seat of the check valve 210 is installed in the passage 88 via which the second accommodating chamber 80 is connected to the suction line 58. The valve seat is formed by the end section of the passage 88 that faces the suction line 58.

Air that is still in the pump 12 when starting the high-pressure cleaning appliance is prevented by means of the check valve 210 from being recirculated via the second bypass line 160 if the second overflow valve 128 has already been opened by the user when starting the high-pressure cleaning appliance. When the high-pressure cleaning appliance is started, the check valve 210 first assumes its closed position and therefore blocks the flow connection from the pressure line 68 to the suction line 58 via the second bypass line 160 independently of the position of the second overflow valve 128. Air that is still in the pump can therefore not get from the pressure line 68 to the suction line 58 via the second bypass line 160. Instead, the air that is in the pump is conducted to the outside via the pressure line 68. To this end, the spring constant of the valve spring 214 is selected such that the pressure of the air in the pump cannot open the check valve 210. If, however, pressurized cleaning liquid gets to the check valve 210 via the second bypass line 160, the pressurized cleaning liquid can open the check valve 210 against the force of the valve spring 214 and can therefore get from the pressure line 68 to the suction line 58 via the second bypass line 160 if the second overflow valve 128 assumes its open position. Therefore, as with the first embodiment shown in Figures 1 to 7, with the second embodiment of a high-pressure cleaning appliance in accordance with the invention shown in Figure 8 the user also has the possibility of switching on and off the pump 12 by means of the switching shaft 172. Furthermore, by means of the switching shaft 172, the user can choose whether he wants to discharge 100 % of the pressurized cleaning liquid via the pressure line 68 or whether he would like to recirculate some of the pressurized cleaning liquid so that the energy consumption of the high-pressure cleaning appliance is reduced. A third embodiment of a high-pressure cleaning appliance in accordance with the invention, which is denoted in its entirety by reference numeral 220, is shown schematically in Figures 9, 10 and 11. The high-pressure cleaning appliance 220 is similar in construction to the high-pressure cleaning appliance 10 explained with reference to Figures 1 to 7. The same reference numerals are therefore used in Figures 9 to 11 as in Figures 1 to 7 for identical components, and, in order to avoid repetitions, reference is made to the above explanations in connection with these components.

In the high-pressure cleaning appliance 220 shown in Figures 9, 10 and 11, the electric motor 14 can also be automatically switched on and off in dependence upon the flow rate of the cleaning liquid flowing through the pressure line 68, and a flow path from the pressure line 68 to the suction line 58 of the high-pressure cleaning appliance 220 via the first bypass line 96 can be opened in dependence upon the flow rate of the cleaning liquid flowing through the pressure line 68, as has already been explained in detail hereinabove. In addition, the high-pressure cleaning appliance 220 also has a second bypass line 160 in which a second overflow valve 128 which is manually actuatable by the user is arranged. Differently from the high- pressure cleaning appliance 10, the second overflow valve 128 in the high-pressure cleaning appliance 220 is arranged in a second accommodating chamber which is aligned perpendicularly to the longitudinal axis of the first accommodating chamber 78. The cylindrical chamber wall 222 and the longitudinal axis 224 of the second accommodating chamber are immediately apparent from Figures 9 and 10.

In the high-pressure cleaning appliance 220, an actuating device 226 with a switching shaft 228 whose longitudinal axis 230 is aligned parallel to the longitudinal axis 224 of the second accommodating chamber is used to actuate the second overflow valve 128. By means of the switching shaft 228 of the high-pressure cleaning appliance 220, in a manner corresponding to that with the switching shaft 172 of the high-pressure cleaning appliance 10, a second switching element of the high-pressure cleaning appliance 220 can be actuated in order to switch on and off the electric motor 14.

The switching shaft 228 is surrounded by a guide sleeve 234, which is rotationally fixedly connected to the switching shaft 228 and which forms on its outer side a sliding link 236 in the form of a slide surface 240 which has first slide surface sections 242 and second slide surface sections 244. The first slide surface sections 242 extend in the circumferential direction of the guide sleeve 234 in a plane aligned perpendicularly to the longitudinal axis 230 of the switching shaft 228, and the second slide surface sections 244 have a slope in relation to this plane and so they are configured in the manner of a helical line or the turn of a thread. Two diametrically opposed sliding link blocks 246, 248 each lie against a first slide surface section 242 or a second slide surface section 244. The sliding link blocks 246, 248 are rigidly connected to a fork-shaped swivel lever 250 which is mounted on the pump housing 254 of the high-pressure cleaning appliance 220 for swivel movement about a swivel axis 252 aligned parallel to the longitudinal axis of the pressure line 68.

When the switching shaft 228 is rotated about its longitudinal axis 230, the swivel lever 250 performs a swivel movement in dependence upon the rotational position of the switching shaft 228 and so the second overflow valve of the high-pressure cleaning appliance 220 can be manually opened and closed. The actuation of the second overflow valve is effected in a manner corresponding to that with the high-pressure cleaning appliance 10.

In a first switching position of the switching shaft 228, the high-pressure cleaning appliance 220 is switched off and its second overflow valve assumes its closed position. When the switching shaft 228 is rotated to a second rotational position, the electric motor 14 of the high-pressure cleaning appliance 220 is switched on, the second overflow valve does, however, remain in its closed position as the two sliding link blocks 246, 248 merely slide along a first slide surface section 242 during this rotational movement and do therefore not change their position relative to the switching shaft 228. When the switching shaft is moved to a third rotational position, the electric motor 14 remains switched on, but during this rotational movement the sliding link blocks 246, 248 slide along a second slide surface section 244 and therefore perform a substantially axially aligned movement in relation to the longitudinal axis 230 of the switching shaft 228 and so the swivel lever 250 is swivelled about the swivel axis 252 and the second overflow valve of the high-pressure cleaning appliance 220 is thereby opened.

Therefore, with the high-pressure cleaning appliance 220 the user also has the possibility of switching on and off the appliance in a very simple way and, if required, of opening the second bypass line 160 in order to reduce the energy consumption of the high-pressure cleaning appliance 220.

Claims

A high pressure cleaner (10, 220) with an electric motor (14) and a pump (12), wherein the pump (12) has at least one pump chamber (44) as at least one piston (46, 48) that can be moved back and forth , enters and which is connected via an inlet valve (56) to a suction line (58) and via an output valve (62) to a pressure line (68) and wherein the pump (12) has a first bypass pipe ( 96), via which the pressure line (68) is connected to the suction line (58), and in which is arranged a first overcurrent valve (98), a closure body (110) of the first overcurrent valve (98) depending on a state size of a cleaning liquid flowing through the pressure line (68) can be automatically moved back and forth between a closing position closing the first bypass line (96) and an open position releasing the first bypass line (96), and the electric motor (14) depending on the the flow rate of the cleaning fluid flowing through the pressure line (68) automatically can be switched on and off, characterized in that the pump (12) has a second bypass line (160), via which the pressure line (68) is connected to the suction line (58) and in which a second overcurrent valve (128) is provided, whose closing body (146) can be moved manually between a closing position closing the second bypass line (160) and an open position releasing the second bypass line (160).

High-pressure cleaner according to claim 1, characterized in that the high-pressure cleaner (10, 220) comprises a manually operable (168, 226) operating device having a plurality of operating positions, whereby the electric motor (14) is operated by means of the operating device (168, 226). ) can be switched on and off and the second overcurrent valve (128) can be opened and closed.

High pressure cleaner according to claim 2, characterized in that the operating device (168, 226) has an operating element which can optionally be moved back and forth between a first operating position in which the electric motor (14) is switched off, a second operating position in which the electric motor (14) is turned on and the second overcurrent valve (128) is closed and a third operating position where the electric motor (14) is switched on and the second overcurrent valve (128) is opened

High pressure cleaner according to claim 3, characterized in that the operating element comprises a rotatably mounted switch shaft (172, 228) coupled with a switching element (174) of the high pressure cleaner (10, 220) and with the second overcurrent valve (128).

High pressure cleaner according to claim 4, characterized in that the switch shaft (172, 228) is directly connected to the switch element (174) and is coupled via at least one switching element (178, 162, 250) to the second overcurrent valve (128).

High-pressure cleaner according to claim 4 or 5, characterized in that a switching cam (176) is arranged on the switching shaft (176) which, depending on the pivot position of the switching shaft (172), cooperates with a switching element (178), where via the switching element (178) a movement of the switch shaft (172) to the shutter body (146) of the second overcurrent valve (128) can be transmitted.

High-pressure cleaner according to claim 4 or 5, characterized in that a switch (236) is arranged on the switch shaft (236) which cooperates with a clutch element (250), whereby a movement of the switch shaft (250) can be transmitted via the clutch element (250). 228) to the closure body (146) of the second overcurrent valve (128).

High-pressure cleaner according to one of claims 3 to 7, characterized in that the control element is coupled via the rotary arm (178, 250) to the second overcurrent valve (128).

High pressure cleaner according to claim 8, characterized in that the swivel arm (178, 250) is arranged on the outside of a pump housing (170, 254) of the high pressure cleaner (10, 220).

High pressure cleaner according to claim 8 or 9, characterized in that the closing body (146) of the second overcurrent valve (128) is displaceable and the pivot arm (178, 250) cooperates with the closing body (146).

High-pressure cleaner according to claim 10, characterized in that the swivel arm (178) has a long and a short bar arm (182, 184), wherein the long bar arm (182) abuts the operating element and the short bar arm (184) acts on the shutter body (146).

High-pressure cleaner according to claim 11, characterized in that the short rod arm (184) has a rod body (186) on which a pressure element (192) is slidably mounted, which cooperates with the closing body (146).

High-pressure cleaner according to claim 12, characterized in that a compression spring (200) is clamped between the rod body (186) and the pressure element (192).

High pressure cleaner according to one of the preceding claims, characterized in that the closing body (146) of the second overcurrent valve (128) in its closing position can be actuated by a closing force of the pressure of the cleaning liquid contained in the pressure line (68).

High pressure cleaner according to claim 14, characterized in that the closing body (146) of the second overcurrent valve (128) can be moved to its open position by a displaceable mounted valve lifter (162) against the pressure of the cleaning liquid which acts on the closing body in the closing position.

High pressure cleaner according to one of the preceding claims, characterized in that the pump (12) has a pump head (30) mounted on a cylinder block (28), the cylinder block (28) having at least one pump chamber (44) and the pump head (30) comprises the suction line (58) and the pressure line (68) as well as a first receiving chamber (78) for the first overcurrent valve (98) and a second receiving chamber (80) for the second overcurrent valve (128).

A high-pressure cleaner according to claim 16, characterized in that the first receiving chamber (78) and the second receiving chamber (80) are respectively connected via a passage (86, 88) to a ring channel (40) arranged between the pump head ( 30) and the cylinder block (28).

High pressure cleaner according to one of the preceding claims, characterized in that a non-return valve (210) is arranged in the second bypass line (160).