Washing machine

George Wilson - US patent No. 1,005,093

George Wilson was granted US Patent No. 1,005,093 on 3 October 1911, probably the first automatic washing machine. It combined several inventive concepts: the ability to pre-set the amount of water to be admitted to the wash basket, the ability to run the machine for a pre-set time, and the ability to stop the rotation of the drum and open a discharge valve at the end of the pre-set time. The novelty of the invention consists in the fact that these modes of operation are controlled by a mechanical control device without the intervention of an operator, once the control device has been activated by the operator.

The first claim reads:

The combination with a washing machine, of means for supplying fluid thereto, power-transmitting means, and means actuated by the fluid for disconnecting the power-transmission means. 

In order to interpret claim 1, it is apparent from the description that a plurality of fluids can be supplied in predetermined quantities to the interior of a tub ( casing ) 10 of a washing machine. This prevents an inattentive operator, who is often in charge of several washing machines at the same time, from adding too much or too little of a fluid, which would result in uneven appearance of the treated items.

These several fluids are either clear water or secondary fluids such as soap in liquid form, bluing fluid, bleaching fluid or acid (sour) fluid, as required. The supply of clear water is controlled by a water inlet valve 15 which is opened when the control mechanism is started. A float chamber 30 and the tub 10 are in fluid communication so that the fluid level in the chamber 30 is the same as in the tub 10. Thus, a float 29 in the float chamber 30 follows the fluid level in the tub 10. When the level in the tub 10 has reached a preset level indicated by the float 29, a system of levers connected to the float 29 closes the water inlet valve 15. After the water inlet valve 15 is closed, a timing mechanism is started which connects power to the electric motor to rotate a wash basket (container) 11 in the tub 10. After the preset time has elapsed, the timing mechanism disconnects the power to the electric motor or disengages a clutch between the electric motor and the wash basket 11 and opens a discharge valve 58 to empty the tub 10.

Before starting the control mechanism, the operator may have filled a reservoir 40 with an appropriate amount of liquid washing soap if the washing machine is being used for a cleaning cycle. If the washing machine is used for a rinsing cycle, the reservoir 40 may be left empty. In the case of rinsing white fabrics, which usually acquire a slight grey or yellow tint, the reservoir 40 can be filled with a bluing liquid for a rinsing cycle. By adding a trace of blue to the slightly off-white colour of these fabrics, they will appear whiter.

The advantage of the separate reservoir is that the secondary liquid is not added to the tub 10 until the full amount of water has been supplied. This avoids any part of the fabrics being exposed to the concentrated secondary fluid, which could lead to differences in the appearance of the fabrics after washing.

At the same time as the motor is started, immediately after the water inlet valve 15 has been closed, the control mechanism opens a valve 42 at the lower end of the reservoir 40 and the contents of the reservoir 40 flow by gravity into the tub 10.

Under Article 84 EPC (A claim shall be supported by the description), claim 1 would probably not be allowed by the European Patent Office today because the description does not disclose that the fluid directly disconnects the power transmitting means. The description only discloses that the sensed fluid level triggers a timing mechanism which disconnects the power-transmitting means after a preset time has elapsed.

The Dish washer

The American Cleaning Institute, a non-profit trade association representing manufacturers of household, industrial and institutional cleaning products summarised how to wash dishes by hand in 5 steps:

  1. Prepare - scrape off food
  2. Fill - get clean, hot, soapy water
  3. Washing - scrubbing under water
  4. Rinse - rinse off all the suds and residue
  5. Dry - air or towel dry


Mechanical dishwashers replicate steps 2 to 5 to make people's lives easier.

Joel Houghton - US Patent No. 7,365

The first patent for a dishwasher was granted to Joel Houghton in 1850. US Patent 7,365 'Table Furniture Cleaning Machine' described a cylindrical vessel A B C D E F made of metal or wood for receiving a conical rack i on which the dirty dishes were placed. One side A C E F of the cylinder, e.g. a fourth, is left open from near the top to the bottom. Boiling water is poured from the top of the cylinder onto the dishes in the rack. A mechanism similar to the wheel of a mill can be turned by a crank d. This mechanism consists of two dippers b-b' (elongated buckets) which, when passing through the lowest position of the wheel, scoop up water, carry it up and then throw it forward through the opening of the cylinder onto the rack with the dirty dishes. A curb a-a' around the wheel prevented the water from flowing back before the scoops reached the top of the wheel. The conical rack could be turned by hand around a shaft H so that all the dishes were exposed to the splashing water. After washing, the dishes would be left in the rack i to dry. It is understandable that the cleaning efficiency of this design was not convincing and it does not seem to have been a commercial success.

Joel Houghton's dishwasher showed one of the basic elements of the modern dishwasher, a rack on which the dishes or objects could be placed so that they emptied themselves. There was also the idea of throwing water against the plates with force, although the proposed bucket version did not achieve much.



Allen G. Ingalls - US Patent No. 355,088

It was 26 years before the next patent was filed for a dishwasher. A tank A contained the water for washing the dishes, which were placed in an annular basket. The dishes were placed in the annular basket through a door in the top of the dishwasher. The main difference from the prior art was the use of pumps which sprayed water over the dishes from fixed nozzles arranged around the virtual axis of the annular basket G, pointing radially outwards towards the dishes rotating in the annular basket around the nozzles. The annular basket was formed by attaching a coarse mesh wire cloth to a suitable frame. The ring basket contained a wire mesh pocket 30 to hold soap for soaping the water in which the dishes were washed.

The ring-shaped basket was turned by cogwheels driven by a crank e. A lever g raised the bucket from a lower position to an upper position. The lower position was for washing the dishes and the upper position for drying them. In the lower position, the cogwheels engaged with the wheels of the pump mechanism. In the upper position the pumps were disengaged and the remaining water on the dishes was centrifuged off.  

A new feature were lamps which heated the water in the tank and were also used to dry the crockery after cleaning.

Josephine G. Cochran - US Patent No. 355,139

US Patent No. 1,323,216

On 2 October 1916, A. E. Cornwall and C. D. Enochs filed a patent application for a dishwasher, which contained a number of inventions expressed in 18 claims. From today's perspective, the most important step forward was the introduction of a cam timer, which allowed the dishwasher to run unattended.

The Microwave Oven

Percy Spencer supervised production of the microwave magnetron at Raytheon. He developed a technique for mass-producing radar magnetrons and increased the production rate from xx magnetrons per day to xxx magnetrons per day by using laminated stenciled copper. Prior to this development, each magnetron had to be carefully machined to fine tolerances to ensure the correct operating frequency. ( ... / Robert V. Decareau, The Amana Story in "The Microwave News Letter", Vol. x, No. 2, 1977). 

The legend that Percy Spencer was inspired to use microwaves to heat food by a melting chocolate bar while standing next to a working magnetron does not seem to have been confirmed by Spencer himself. However, he is named as an inventor in basic patents filed by Raytheon for heating foodstuff. US 2495429 claims the method of treating food, the steps of which include: generating electromagnetic wave energy of a wavelength falling in the micro wave region of the electromagnetic spectrum; concentrating and guiding said wave energy within a restricted region of space and exposing the foodstuff to be treated to the energy so generated for a period of time sufficient to cook the same to a predetermined degree.

The original US 2,495,429 comprised only method claims. A divisional patent, the US2605383, "Means for treating food stuff", claimed a microwave power source comprising a pair of cavity magnetron oscillators, a source of alternating current, means connecting the inputs of said magnetron oscillators in push-pull to said alternating current source, and means coupling the outputs of said magnetron oscillators to a common load, said load comprising means for concentrating and guiding said energy from said magnetron oscillators toward and into the region of foodstuff with sufficient intensity to raise said foodstuff to cooking temperature. 

Raytheon's first microwave oven, the Radarange, was purchased by a Cleveland restaurant in 1947 for $3,000.

Raytheon's microwave oven patents were extremely broad and could have blocked the sale of microwave ovens for a long time. Instead, Raytheon chose not to do so in the interest of achieving wider acceptance of the product in a shorter period of time. In 1953 Raytheon signed a license agreement with Tappan, and between 1953 and 1961 similar license agreements were signed with Hotpoint, Westinghouse and Litton. (Leo. R. Reynolds, The History of the Microwave Oven", Microwave Wor... Vol. 10, No.5 1989, p. 11)

The 1955 model, produced for home use, failed to sell well due to its high price and customer confusion about how to use it. (https://americanhistory.si.edu/collections/search/object/nmah_1088040 ). The RL-1, developed by Tappan in conjunction with Raytheon, was the first microwave oven designed for home use. With a retail price of $1,295, only 34 units were manufactured in 1955, the first year of production. The company sold a total of 1,396 units before production ceased in 1964. (Ibid). This was less than 0.025% of the number of households of the US in 1964.

In early 1955, Raytheon's Radarange Division added a fully equipped commercial test kitchen and hired a chef to run it in preparation for launching microwave ovens from its own production. Despite the establishment of a food laboratory for scientific research into microwave cooking Raytheon hardly could break even in 15 years. (Ibid, p. 5). 

The turning point was Raytheon's acquisition of Amana Refrigeration, Inc. of Amana, IA, in March 1965. Amana was founded in 1934 as a manufacturer of refrigerators, freezers and other refrigeration equipment. When Raytheon purchased the company, it had net sales of about $25 million. Sales doubled by 1967, the year the Amana Radarange microwave oven was introduced to the consumer market. In-store demonstrations were an essential marketing tool to convince consumers of the benefits of the microwave, which was a completely new way of cooking and reheating food. (Robert V. Decareau, The Amana Story in "The Microwave News Letter", Vol. x, No. 2, 1977). That probably pushed the total ownership rate in the US over 0.1%. 

The breakthrough came with the Touchmatic Radarange microwave oven, introduced in the mid-1975s.  Dubbed 'the oven with a brain' by some, the Touchmatic used a microprocessor unit to programme defrosting, cooking or a combination of the two. When a programme was completed, the oven would switch off with an audible signal and then display the time. These "gimmicks" captured the imagination of consumers buying ovens. Amana expanded its multi-million-dollar advertising programme to take full advantage of the Touchmatic's glamour. The sophisticated user interface would have such an impact on the market that other oven manufacturers would install crash programs to introduce their own versions. By 1976, a brand new microwave oven cost less than $300 and was now available to a wider range of consumers.