Pneumatic valves are compact and flexible

A pneumatic valve has been launched that is compact, lightweight and cost effective, partly due to a novel single-piece pilot cartridge. Dean Palmer reports A new range of pneumatic valves has been developed that looks ideal for robotics, automation, electronics, semiconductor and miniature handling tasks that require a compact, low flow rate, low power consumption valve. Launched in the UK last month, Bosch Rexroth's LS04 (low, single valve with a flow rate of up to 400l/min) series of pneumatic valves offers customers a reduced installation size, compact dimensions and a lightweight construction. The 'XS' (extra small) series valve weighs just 30g and has a width of 10.8mm, which means machine builders or design engineers can mount the valve directly onto sensitive machine components, robots or assembly equipment. The compactness of the valve is down to Bosch's core competence in plastics technology. Uniquely, the integrated pilot cartridge housing was injection moulded in one piece, enabling the total number of valve parts to be reduced, with associated manufacturing and assembly costs reduced too. The LS04 series is available in three different designs: a miniature valve, the XS series; a standard 'AF' (all functions) valve which offers flow rates up to 250 l/min; and a valve terminal system with a flow rate of up to 330 l/min. All the variations of the LS04 series are lightweight and made almost entirely from engineering polymers. The 'XS' series are inline single, 5/2 spring return valves with flow rates of up to 200 l/min. The valves have push-in connectors for 4mm diameter hose and a pretty impressive switching time of just 9ms. Most competing valve manufacturers offer 16-18ms switching times. Working pressure is from 3 to 8 bar and operating temperature range is from 0°C up to 50°C. Protection class is up to IP65 (M8) with IP50 as standard. Mounting is via two through-holes reinforced with metal sleeves and connection is via an M8 three-pin or standard plug. The spool on the XS valve is made from aluminium, housed in a compact pilot body made from a high performance engineering polymer (polyoxymethylene or POM). Most competing valves in the market use an aluminium body. The seals on the spool are made from polyurethane and the return spring is stainless steel. The electronics housing, which protects the PCB with LED and protective circuit, is also made from acetal (POM). The seals on the XS series are the same as those already being used on Bosch's well-established HF04 series valves. Trevor ??? demonstrated the valve to Eureka at the company's UK head office in St Neots, Cambridgeshire last month. He explained: "A thorough DFMA [design for manufacture and assembly] analysis was carried out on the LS04 series by our design team out in Germany. The novel pilot cartridge is injection moulded in one piece with the spool placed directly inside, which cuts manufacturing and assembly time and costs significantly. "There are other innovations too. The valves do not use any bolts and the whole unit is fastened together using pins, another method of reducing the valve's overall component count," he added. He also said that, in the UK market, the company found that many of its customers were fastening or bolting their valves through two points to a machine. This meant that the spool could sometimes distort and actually stop functioning. Power consumption is also pretty low compared to other valves: 0.7W compared to a typical 1 to 1.5W for most other products. The electrical connections vary across the three types of valve: the inline single valves are equipped with an M8 connector or standard connector; the valve terminal system comes with multi-pin connection that can be used to control up to 24 coils. This means users can implement mixed design configurations with single and double solenoid, or double 3/2-way valves. Also, users can create different pressure zones or supply circuits in the valve terminal system using separators that can be positioned anywhere, giving them flexibility to adapt the valves to individual customer demands. The valve terminal system (VTS) LS04 series is Bosch's modular valve system, offering users mixed configurations of mono-stable and bi-stable valve functions. Up to 12 valve positions are possible. Operating voltage is 24V DC, with a ±10% voltage tolerance. Status display is a yellow LED and mounting is via four through-holes (reinforced with metal sleeves) or on DIN rails. Electrical connection is via 25-pin D-Sub connector, which can be rotated through 90 degrees on the same end plate. There are three variants enabling vertical connection on top, a radial connection and a vertical connection with an IP50 protection class thanks to an encapsulated D-sub plug. The body of the VTS is made from POM, but the valve spool this time is made from a copper-zinc alloy. The valves are suitable for lubricated (class 7-5-4) or oil-free (class 6-4-3) compressed air. Pointers: * The LS04 valve series benefits from reduced installation size, compact dimensions and low weight * Comes in two single valve versions and a valve terminal system version * Uses proven plastics technology * Integrated push-in connectors, protective circuit with LED