WO1991003951A1

WO1991003951A1 - Temperature sensing steam wand

Info

Publication number: WO1991003951A1
Application number: PCT/US1990/003276
Authority: WO
Inventors: Howard W. Selby, Iii
Original assignee: Selsys Corporation
Priority date: 1989-09-06
Filing date: 1990-06-08
Publication date: 1991-04-04
Also published as: AU5941790A

Abstract

A steam wand (10) in an espresso coffee machine includes a temperature sensor (14) that senses the temperature of the liquid being heated by the steam wand (10), and either signals the operator that a predetermined temperature has been reached, or automatically terminates the steaming process when the predetermined temperature has been reached.

Description

Temperature Sensing Steam Wand

Technical Field

This invention relates to steam wands that are used in espresso coffee machines, and specifically to a steam wand apparatus that is constructed and arranged to sense the temperature of the steamed liquid during the steaming process.

Background Art

Steam wands on conventional espresso coffee machines are used to heat liquids. Typically the liquid that is heated is milk for use in espresso drinks such as cappuccino and cafe latte.

The steam that issues from the steam wand both heats and foams the milk. The temperature to which the milk is heated is critical. For example, if the milk is scalded, the taste of the resulting espresso drink will be adversely affected.

In the use of conventional steam wands, the operator determines when the milk has reached the proper temperature, and then manually shuts off the steam supply. This determination is usually made by the operator feeling the temperature of the pitcher in which the milk is being heated. Without considerable experience, it is easy for the operator to scald the milk, or alternatively the milk may not be adequately heated.

Disclosure of the Invention

It would be desirable to provide a steam wand that measures the temperature of the liquid being heating, and that either signal an operator or shuts itself off when a predetermined liquid temperature is reached. In view of the foregoing, it is an object of this invention to provide a steam wand that senses the temperature of the liquid it is heating, and that signals the operator when a predetermined liquid temperature is reached.

It is a further object of this invention to provide a steam wand that automatically shuts off the supply of steam and/or signals the operator when the liquid being heating reaches a predetermined temperature.

These and other objects of the invention are accomplished in accordance with the invention by providing a conventional espresso coffee machine steam wand with a temperature sensor that operates to measure the temperature of the liquid being heated by the steam wand. In accordance with a feature of the invention, this temperature sensor and its associated control means are capable of providing variable temperature settings that are controlled by the operator.

When the liquid being heated by the steam wand reaches the temperature that has been set by the operator on the temperature sensor control means, a signal is provided to the operator. The operator can then manually stop the steaming process, or alternatively the steaming process is stopped automatically. The heated liquid will now be heated to the temperature that was set by the operator.

Rather than, or in addition to signalling the operator, the temperature sensor and/or control means can be connected to an automatic steam shut-off valve that is located in the piping that supplies steam to the steam wand. In such a configuration, steam flow to the steam wand is automatically shut off when the desired liquid temperature is reached.

Further features ,of the invention, its nature and various advantages thereof will be apparent from the accompanying drawings and the following detailed description of the invention. Brief Description of Drawings

FIG. 1 is a diagram showing the steam wand, temperature sensor, control circuit means, and steam flow plumbing.

Detailed Description of the Invention

Referring now to the drawing, there is shown in the figure a steam wand 10, a steam discharge head 12, a temperature sensor 14, an indicator signal means 16, a control valve 18, steam wand plumbing 20, a steam source 22 and related control circuitry or means 24. Control circuit means 24 is constructed and arranged to facilitate adjustable control of a set point temperature to which the milk is to be heated, as is well known by those of skill in the art. Control circuit means 24 is connected in controlling relation to control valve 18, and operates to close value 18 when the set point temperature is reached, as is well known by those skilled in the art.

Temperature sensor 14 is physically located at the end of steam wand 10, near steam discharge head 12. However, sensor 14 is mounted in such a way as to measure the temperature of the liquid in which steam wand 10 is immersed, and is not appreciable affected by the heat of the steam itself. While the details of this mounting arrangement are not critical to the invention, sensor 14 is located to be submerged in the liquid being heated so long as steam discharge head 12 is likewise submerged therein.

Temperature sensor 14 and its control means 24 are set to be activated when the liquid in which steam wand 10 is immersed reaches a specific set point temperature. This temperature setting can be of a fixed temperature magnitude, such as would be provided by a commercially available sensor that meets the temperature specification of the espresso coffee machine, or the temperature setting is preferably adjustable in magnitude by the operator, by way of manual operation of control means 24. Temperature sensor 14 is connected to an indicator signal means or device 16, such that when temperature sensor 14 is activated, signal device 16 is also activated. While not critical to the invention, indicator signal device 16, for example a light source and/or a audible buzzer, may be incorporated into the control panel of the espresso coffee machine, so as to be readily observable by the operator.

Indicator signal device 16 may include a variety of output means that operates to attract the attention of the operator, such as a light or a buzzer. In such a configuration, the operator is notified by indicator signal device 16 when the liquid being heated has reached the predetermined temperature thdt was set in temperature sensor 14. The operator can then manually terminate the steaming process, for example by manual operation of valve 18.

In the preferred embodiment of the invention, temperature sensor 14 is connected directly to control valve 18 that is located in steam wand plumbing 20. Control valve 18 controls the flow of steam from steam source 22, through steam wand plumbing 20, to steam wand 10, and to steam discharge head 12. Control valve 18 may be a well known solenoid activated valve mechanism that automatically shuts off the supply of steam when the valve is activated by temperature sensor 14, by way of control means 24. In this configuration, the steaming process is automatically terminated when the desired temperature is reached, with no intervention being required on the part of the operator.

Claims

1. An espresso coffee machine comprising: a source of steam, elongated steam wand means, steam wand plumbing means connecting said steam wand to receive steam from said source of steam, a steam discharge head located at one end of said steam wand and adapted for heating a supply of milk in which said steam discharge head is immersed, temperature sensor means mounted at said one end of said steam wand in a manner to measure milk temperature to the exclusion of measuring steam temperature; and control means connected to be controlled by said temperature sensor means.

2. The espresso coffee machine of claim 1 including; a steam control valve located in said steam wand plumbing.

3. The espresso coffee machine of claim 2 wherein said control means includes means for setting a preset milk temperature to be achieved by operation of said steam discharge head, and means connecting said steam control valve to be controlled by said control means, said control valve being operable to automatically shut off the supply of steam to said steam discharge head when a preset milk temperature is reached.

4. The espresso coffee machine of claim 3 wherein said preset milk temperature is a fixed temperature.

5. The espresso coffee machine of claim 3 wherein said preset milk temperature is a manually variable temperature.

6. The espresso coffee machine of claim 1 including indicator means controlled by said control means and providing output stimulus to which an operator is sensitive.

7. The espresso coffee machine of claim 6 wherein said indicator means provides sound and/or light output stimulus to which an operator is sensitive.

8. A method of providing an espresso coffee machine including means for heating a supply of milk, comprising the steps of, providing a source of steam, providing elongated steam wand means, providing steam wand plumbing that connects said steam wand to receive steam from said source of steam, providing a steam discharge head at one end of said steam wand means for heating a supply of milk in which said steam wand means is immersed, providing temperature sensor means at said one end of said steam wand means in a manner to measure milk temperature to the exclusion of measuring steam temperature; and providing control means connected to be controlled by said temperature sensor means.

9. The method of claim 8 including the steps of providing means for setting a preset milk temperature to be achieved by operation of said steam discharge head, providing a steam control valve located in said steam wand plumbing, and providing means connecting said steam control valve to be controlled by said control means, said control valve being operable to automatically shut off the supply of steam to said steam discharge head when a preset milk temperature is reached.

10. The method of claim 9 wherein said preset milk temperature is a fixed temperature.

11. The method of claim 9 wherein said preset milk temperature is a manually variable temperature.

12. The method of claim 9 including the step of providing indicator means output such as sound and/or light.

13. The method of claim 10 including the step of providing indicator means output such as sound and/or light.