Robert BOSCH
Acoustic Washing Machine
Mechanix Illustrated (June 1951)

Sound Waves get your wash clean

Sound Waves get your wash clean, claims Robert Bosch of Stuttgart, Germany. This seven-pound machine works on principle of auto horn. Hooter must sound for five minutes. Cost is $32.

Electrical appliance for producing oscillations or vibrations for laundry purposes

Inventor: BOSCH GMBH ROBERT [DE]     


Improvements in or relating to Laundry or Washing Appliances We, Robert Bosch G M B H, a German Company, of Breitscheidstrasse 4, Stuttgart, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-

The present invention relates to electrical appliances for producing oscillations or vibrations in liquids for laundry or washing purposes.

It has already been proposed to clean material to be laundered or washed, especially underwear, by rapidly vibrating or oscillating the washing water, in which the material to be laundered is immersed, by means of a membrane or diaphragm which is immersed or plunged into the water, with the object of releasing and washing away particles of dirt or other foreign matter adhering to the material being laundered In a known washing device of this kind, the diaphragm is caused to vibrate rapidly by means of a small electric motor through a rod or bar to which the diaphragm is fitted The disadvantages of this device consist in the fact that revolving parts requiring the attention of an operator and subject to wear and tear, are provided for translating a rotary movement into the required oscillating or vibrating movement.

It is also known to use ultra sound or supersonic waves for laundry purposes The production of such waves, however, requires devices which are too cumbersome and expensive for use in small laundry installations for domestic use Washing devices have also been proposed in which a diaphragm is excited by a solenoid in such a manner that the vibrations of the diaphragm are entirely unrestricted In practice, however, this vibratory effect of the diaphragm is insufficient for washing purposes and the washing devices so fitted are thus unsatisfactory.

It is well known to construct audible warning devices such as horns with an electromagnetically operated diaphragm, the movement of which is limited in at least one direction by a stop.

According to the present invention an electromagnetically operated liquid oscillating or vibrating laundry or washing appliance is characterised in that movement of a diaphragm operated by an electromagnet is abruptly limited in at least one direction by a stop and in that the electromagnetic driving means are enclosed in a casing sealed against the ingress of liquid by the diaphragm and provided with means to prevent undue pressure rise within the casing sufficient to prejudice the operation of the diaphragm.

The invention is further described with reference to the accompanying drawings which illustrate by way of example eight embodiments of the invention, suitable for alternating current, and in which:

Fig 1 is a longitudinal section of the first embodiment incorporating a single electromagnet and a single diaphragm,

Fig 2 is a longitudinal section of a second embodiment incorporating two diaphragms actuated by a single electromagnet,

Fig 3 is a third example having two electromagnets and two diaphragms, also in longitudinal section,

Fig 4 is a further longitudinal section illustrating a fourth embodiment provided with a harmonic wave exciter in the form of an oscillating or vibrating beam or a corrugated circular disc,

Fig 5 is a modification of the form shown in Fig 4

, Fig 6 is a sectional diagram showing an appliance according to this invention fitted in a laundry container, such as a boiler,

Fig 7 is a fifth embodiment partly in longitudinal section of an appliance having a device adapted to compensate or balance the pressure differences in the interior of the appliance,

Fig 8 is a longitudinal section through a Price 2 1 i part of the appliance shown in Fig 7,

Fig 9 is a sixth embodiment in longitudinal section,

Fig 10 is a fragmentary section showing a modification of this embodiment,

Fig 11 is an eighth embodiment, also in longitudinal section, and

Fig 12 shows a curve of acoustic pressure produced in liquids according to the present invention and, for comparison, a sine curve of similar amplitude and frequency.

In the appliance shown in Fig 1, 10 designates a metal diaphragm in the form of a circular disc In the centre of 'the disc is secured a bolt 11, with which a laminated ironbody 12 is firmly connected to constitute the armature of an electromagnet 13 A core 14 of the magnet with a coil 15 is secured to a casing 16 of the appliance The diaphragm 10 is clamped between the edge of the casing 16 and a protective screen or lattice 17 -The diaphragm thus tightly seals the easing around its periphery The bolt 11 is carried at the end remote from the diaphragm in a plate spring 18 clamped to the base of the casing A conduit or tube 19 is fitted to the casing and is co-axial with bolt 11 and so with -the magnet.

Said tube 19 serves as the carrier of the appliance and also for the passage of the electricity supply flex to the coil of the magnet.

When the appliance is connected with the electricity supply mains and set in operation, the electromagnet periodically draws and releases its armature 12 in the rhythm or frequency of the alternating current to and from the core 14 Such reciprocatory movement of the armature is transmitted to the diaphragm and a vibration of oscillation corresponding to twice the mains frequency is consequently imparted to the diaphragm The full vibratory or oscillatory movement which the diaphragm tends to cover when the armature 12 is actuated, is, however, not entirely utilised or exploited, the movement of the armature and so the diaphragm in -a direction towards the core 14 being in fact abruptly interrupted due to the armature 12 impinging upon the -core14 which thus constitutes a stop This impinging action causes the diaphragm to be jarred, i e, the shape of the vibration curve of the diaphragm is influenced in such a way that peak or harmonic vibrations of very high frequency having very sharp rise and fall are superimposed upon the basic vibration of the diaphragm.

The curve of the acoustic pressure produced by such an apparatus is illustrated in Fig 12 part a The very steep waves A are produced by the armature striking the core of the electromagnet In part b there is illustrated, by way of comparison a sine-like curve of similar frequency and amplitude It can be easily seen from comparison of the two curves that the steepness of the waves A is considerably greater than the sine-like curve.

The method of operation of the instrument or appliance when immersed in water is such that the molecules of the liquid entering the casing 16 via the screen or lattice 17 and 70 coming into contact with the outer side of the diaphragm are accelerated by the vibrations of the diaphragm The greatly accelerated water particles are particularly suitable for and capable of removing particles of dirt or other 75 foreign matter, which have already been loosened by the washing powder or other cleaning medium, from the fibre of the clothes or other material being laundered.

In the example shown in Fig 2, two co go axially disposed diaphragms 25 and 26 are spaced apart and clamped or tensioned at opposite sides of a ring 27 together with respective screens or protective lattices 28 and 29 Both diaphragms are firmly connected 85 with the excitation means so that the core 14 is firmly connected with the diaphragm 25 and the armature 12 of the electromagnet is irmly connected with the diaphragm 26 The carrier tube 19 is inserted into an aperture 30 9 o in the ring 27 and is secured therein.

The example in Fig 3 differs from that of Fig 2 in that two diaphragms 31 and 32 are connected with respective armatures 33, 34 of two electromagnets of which the respective 95 cores 35 and 36 are secured on a plate or intermediate partition 38 firmly connected with and dividing the annular casing 37 of the appliance.

In the example shown in Fig 4, an 100 additional vibratory body 40 is disposed on a bolt 39 which is secured to the diaphragm 10 and carries the armature 12 Thus, body 40 is connected with the diaphragm by the -bolt -39.

This additional vibratory body has its own 105 frequency of vibrations, which is substantially above that of the diaphragm 10 The vibratory body 40 suspended in the middle of the diaphragm is in the form of a beam which tapers towards its ends It may also, however, 110 be constructed as a circular disc, which, as shown in Fig 5, is provided with annular corrugations Such additional vibrating or oscillating bodies are particularly suitable for superimposing heavy upper or harmonic vibra 115 tions upon the basic vibrations of the vibration system on the impinging of said vibration system.

The appliance is very simple to use and may be operated as follows After the hot, or 120 preferably, boiling water, to which is added the usual washing agents, and the laundry have been, placed in the boiler 55 (Fig 6), and the appliance has been suspended in the boiler so that its entire casing is submerged below the 125 water level, the electric alternating current is switched on to cause the appliance to operate.

For adjusting the depth to which the appliance is immersed, means such as an adjustable bearing ring 56 may be fitted to the carrier 130 726,774 electrical losses of the driving system, the pressure above atmospheric so produced opens the non-return valve against the action of spring 250, thus compensating for the pressure difference in the casing relative to the 70 atmosphere Upon such compensation being effected, the valve is returned to its seat to seal the interior of the appliance against the admission of air from the atmosphere.

Whilst the appliance remains in operation, 75 no pressure differences will occur between the interior of the casing and the atmosphere which may be sufficient to disturb the desired operation However, as soon as the appliance is further operated in cold water or is taken 80 out of the hot water, switched off, and placed in a cool place, it is possible, due to the airtight casing, for a pressure below atmospheric to occur in the interior of the casing which is sufficient to prevent the correct functioning of 85 the diaphragm, at least until the appliance has been sufficiently heated again It has, however, been found that a casing possessing the required airtight properties cannot be obtained by simple means, as, in the course of time, a go pressure compensation or balance takes place either by way of the cable cores or the cable passage, or by way of the valve.

The example shown in Fig 9 omits the nonreturn valve of Figs 7 and 8 but other means 95 is provided to ensure that the space enclosed by casing 16 and diaphragm 10 will conform to any alteration of the air pressure contained therein, without the difference between the pressure in the casing and the atmosphere 100 thereby assuming such proportions likely to interfere with the action of the appliance For this purpose there are fitted, as for instance to the interior of the casing wall, resilient or yielding hollow bodies 400, having a greater 105 flexibility than the diaphragm, which are formed in this example by bellow-like chambers 410 of thin sheet metal which are sealed from the interior of the casing by means of lids or covers 420, whilst the other end of 110 the bellow-like chambers are soldered or welded to the casing wall The casing wall has holes 430 which communicate with the interiors of the chambers.

In lieu of such sheet metal chambers, sack 115 or bag-like bladders of rubber or similar materials may also be used as shown in Fig.

in which a hollow body 400 a of this kind is provided with a small pipe piece 400 b which passes through the opening 430 of the 120 casing wall The pipe piece has a flange 400 c which is pressed against the casing wall by means of a cap ring 400 d screwed to the casing.

On increase of air pressure within the 125 casing, the bellows are compressed and thus the interior space in the casing is correspondingly enlarged Thus the pressure above atmospheric is limited to an extent which will not affect the action of the vibration producer 130 pipe 19 and which ring also serves to cover the aperture 57 in the lid 58 of the wash boiler, a fixing or clamp screw being carried by the ring to secure same in position The appliance is preferably connected with the main supply through an electrical transformer which reduces the potential to a value which is not dangerous for contact with the body An interrupter device of any suitable type may be built into the appliance so that the appliance may also be used on a direct current supply and a condenser may also be provided across the interrupter device.

The vibrator or oscillation producer shown in Fig 7 consists of a metal diaphragm 10 in the form of a circular disc which is clamped at its outer edge to the casing 16 and connected hermetically with the casing by means of a packing ring 120 The laminated armature 12 of the electromagnet 13 is fixed by means of the bolt 11 to the diaphragm in the centre thereof.

An aperture 160 for bolt 11 is hermetically sealed by a packing disc 170 The core 14 of the electromagnet with the excitation coil 15 is secured to a strut or bridge 20 fixed to the base of casing 16.

The tube or pipe 19 is inserted into the base of the casing and is preferably securely welded thereto A non-return valve 220 is provided at the free end of the pipe in order to prevent the admission of air from the atmosphere to the internal chamber or space of casing 16 The valve, which is shown in detail in Fig 8, has a valve disc 230 formed with a conical bearing surface 240 which normally rests upon a correspondingly shaped seating surface formed at the end of pipe 19 and is pressed against this surface by a spring 250 which abuts against a cap nut 260 screwed on to a threaded collar fixed to this end of the pipe, the cap nut being provided with an aperture 270 for the passage of air This arrangement ensures that the entire area enclosed by the diaphragm 10 and the casing 16 with -the pipe 19 is sealed against the admission of atmospheric air, whereby to avoid entry of moisture into the casing and which would otherwise have an undesirable effect on the So coil of the electromagnet.

A feed cable 280 for the excitation coil 15 extends within the pipe 19 and passes out hermetically through a bore 290 formed in a nipple 300 screwed into the side of pipe 19 A packing ring 310 is located between the nipple and the pipe 19 The outer end of the nipple is formed with a funnel-shaped seating surface 320 for a rubber sealing ring 330 which is pressed by means of a cap nut 340 against the seating surface and the cable 280 passing through it.

When the appliance is used for instance in hot water, the air enclosed in the casing is considerably heated externally by the water surrounding the casing and internally by the 726,774 4 726,774 A further example of the subject of the invention is shown semi-diagrammatically in Fig 11 In this case, the casing 520 enclosing the electromagnet 13 is made as small as the dimensions of the electro-magnet permit in order that the space enclosed by the casing and the diaphragm 10 may be as small as possible As in the other examples, a pipe 19 is connected to the base of the casing for the li) passage of the electricity supply lead 280 to the electromagnet 13 of the appliance The free end of the pipe 19 is in effect widened to form a chamber 530 which is located as remote as possible from casing 520 and is not immersed in the hot water during operation of the appliance As shown, the capacity of the chamber 530 greatly exceeds that of the casing 520, it may, for example, be twice as large as the capacity of the casing 520, in order to maintain low the pressure occurring in the casing 520 on the heating of the air present therein This is achieved, as previously mentioned, by the fact that the casing 520, which is immersed in hot water when the appliance is operated, has a much smaller air capacity than the chamber 530 which thus remains considerably cooler than the casing, the latter being situated outside the water container When the air enclosed in the casing 520 expands owing to heating, -it will mix with the cooler air in the pipe 19 and in the chamber 530 and the temperature rise relative to the atmospheric air, corresponding to the volume and temperature conditions of the two masses of air, will be considerably less than, the temperature rise which would obtain in the air in the casing 520 if the chamber 530 were not present.
de zeen Magazine
19 January 2015

Dolfi is a tiny ultrasonic washing machine for delicate clothes

Product designer Andre Fangueiro has created a small pebble-shaped device that uses ultrasonic sound waves to clean clothes (+ movie).

Andre Fangueiro, founder of Netherlands firm Studio Lata, partnered with engineers at Swiss firm MPI Ultrasonics and new company Dolfi to design a portable machine for washing textiles using ultrasound.

The product – also called Dolfi – aims to remove the need for hand-washing clothes made from fabrics like silk, cashmere and lace that are easily damaged, as well as offer travellers a portable cleaning option.
"The idea of Dolfi came after a few terrible experiences with laundry during my extensive travel," said Dolfi founder Lena Solis, who commissioned Fangueiro to design the product.

"I believe that ultrasonic technology will change the way we wash," she added.

According to the designers, once the Dolfi is placed in a sink or container filled with water and switched on, a device inside it known as a transducer converts electrical power into a range of high-frequency soundwaves that create millions of tiny bubbles in the liquid – an action known as cavitation.

These bubbles implode in on themselves, generating jets that drive detergent and water through the fibres of a piece of clothing without the need for extra movement.

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Fangueiro created a smooth white plastic pebble to house the transducer. The pebble is sealed to make it waterproof and is attached to an electric power source via a flexible cable.

"Its smooth form provides the end user with the sense of friendliness and security that this object would help wash their most precious textiles," said Fanguerio.

"The curvature and acceleration of the surfaces are designed to communicate a high-end consumer product within its technological size. The end result is the small-size, hand-held product that is both high-tech and high-performing."

Dolfi washing machine by Andre Fangueiro

Ultrasonic processes are widely used for cleaning objects made from more solid materials, like jewellery and dental equipment.

Swiss company MPI Ultrasonics developed a range of frequencies that are suitable for cleaning textiles. MPI's Multifrequency, Multimode, Modulated Sonic & Ultrasonic Vibrations technology can be used for a number of different purposes, as the waves it generates can be tuned to suit different materials and functions.

Dolfi washing machine by Andre Fangueiro

"The precisely modulated ultrasonic waves tackle dirt and bacteria right down to the microscopic level. This revolutionary method is able to clean clothing from the inside out without ever damaging or discolouring the fabric," said a statement from Dolfi.

"This compact but powerful device consumes about 80 times less energy than a conventional washing machine, helping you make a huge positive impact for the planet and, of course, for your wallet."

Dolfi washing machine by Andre Fangueiro

Dolfi's name is a "tribute to dolphins", animals the company describes as "the most advanced users of ultrasound".

Dolfi will launch a crowdfunding campaign to raise $100,000 (£66,000) for production of the device on online platform IndieGogo later this month. A portion of the funds will be donated towards dolphin research and welfare organisations.

Dolfi is a small ultrasonic washing machine for delicate clothes

This movie demonstrates a small pebble-shaped device by product designer Andre Fangueiro that uses ultrasonic sound waves to clean clothes.

Dolfi: Next Gen Washing Device

Dolfi: Next Gen Washing Device


A big THANKS to our almost 8000 contributors who made Dolfi a reality!

We are now at the final stage of setting up for manufacturing and have stopped taking pre-orders.

To avoid delays in shipping the rewards to our backers we have locked in the quantities for the first production batch and will not be offering pre-orders anymore.

We’ll start taking orders again once we ship the rewards to our Indiegogo supporters.

If you missed out on our campaign, subscribe HERE to be informed once Dolfi can be ordered!

"Approximately 1,206 results found in the Worldwide database for: ultrasonic washing machine in the title or abstract"

… not to mention "ultrasonic cleaners".

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