Toyota Electronic Modulated Suspension

Last updated

TEMS (Toyota Electronic Modulated Suspension) is a shock absorber that is electronically controlled (Continuous Damping Control) based on multiple factors, and was built and exclusively used by Toyota for selected products during the 1980s and 1990s (first introduced on the Toyota Soarer in 1983 [1] ). The semi-active suspension system was widely used on luxury and top sport trim packages on most of Toyota's products sold internationally. Its popularity fell after the “bubble economy” as it was seen as an unnecessary expense to purchase and maintain, and remained in use on luxury or high performance sports cars.

Contents

Summary

TEMS consisted of four shock absorbers mounted at all four wheels, and could be used in either an automatic or driver selected mode based on the installation of the system used. The technology was installed on top-level Toyota products with four wheel independent suspension, labeled PEGASUS (Precision Engineered Geometrically Advanced SUSpension). Because of the nature of the technology, TEMS was installed on vehicles with front and rear independent suspensions. The technology was modified and installed on minibuses or minivans like Toyota TownAce/MasterAce rear independent suspensions, and the top trim package on the Toyota HiAce.

Based on road conditions, the system would increase or decrease ride damping force for particular situations. The TEMS system was easily installed to suit ride comfort, and road handling stability on small suspensions, adding a level of ride modification found on larger, more expensive luxury vehicles. The technology was originally developed and calibrated for Japanese driving conditions due to Japanese speed limits, but was adapted for international driving conditions with later revisions.

As the Japanese recession of the early 1990s began to take effect, the system was seen as an unnecessary expense as buyers were less inclined to purchase products and services seen as “luxury” and more focused on basic needs. TEMS installation was still achieved on vehicles that were considered luxurious, like the Toyota Crown, Toyota Century, Toyota Windom, and the Toyota Supra and Toyota Soarer sports cars.

Recently the technology has been installed on luxury minivans like the Toyota Alphard, Toyota Noah and the Toyota Voxy.

The TEMS system has been recently named “Piezo TEMS” (with piezoelectric ceramics), [2] “Skyhook TEMS” “Infinity TEMS” and more recently “AVS” (Adaptive Variable Suspension).

Configuration settings

The system was deployed with an earlier two-stage switch labeled “Auto-Sport”, with a later modification of “Auto-Soft-Mid-Hard”. Some variations used a dial to specifically select the level of hardness to the driver's desires. For most driving situations, the “Auto” selection was recommended. When the system was activated, an indicator light reflected the suspension setting selected. The system components consisted of a control switch, indicator light, four shock absorbers, shock absorber control actuator, shock absorber control computer, vehicle speed sensor, stop lamp switch, with a throttle position sensor and a steering angle sensor on TEMS three stage systems only. All the absorbers are controlled with the same level of hardness.

Operation parameters of TEMS

The following describes how the system would activate on the earlier version installed during the 1980s on two stage TEMS

The system chooses the "SOFT" selection, to provide a softer ride.

The system selects the "HARD" selection and determines that at high speeds, it assumes a more rigid configuration for better ride stability, and to reduce roll tendencies.

In order to prevent “nose dive”, the process proceeds to "HARD" automatically damping force until it senses the brakes to be at the"SOFT" setting. It will return to the "SOFT" state when the brake light is off, and the pedal has been released after 2 seconds or more.

To suppress suspension “squat” the system switches to "HARD" based on accelerator pedal position and throttle position.

To suppress suspension “roll” the system switches to "HARD" based on steering angle sensor position.

The system remains in the "HARD" position regardless of driving conditions. (For 3-stage systems, the system automatically chooses between the “MID” and the "HARD" configurations - by the other words, the "SOFT" stage is excepted)

Vehicles installed

The following is a list of vehicles in Japan that were installed with the technology. There may have been vehicles exported internationally that were also equipped.

Super Strut (MacPherson modified strut)

This section was translated from the Super Strut Suspension article on Japanese Wikipedia at ja:スーパーストラットサスペンション.

Super strut suspension is a high-performance suspension for automobiles developed by Toyota. On vehicles equipped, the abbreviation listed was "SSsus" and was first installed on the AE101 Corolla Levin / Sprinter Trueno for 1991 .

Overview

This is a MacPherson strut type suspension that has been improved to compete with double wishbone type suspensions. It suppressed the change in camber angle that occurs when the suspension is in motion, and as a result it greatly increases handling stability and grip limit while turning. For front wheel drive sports coupes, there arose a need for an inexpensive upgrade that could be installed on vehicles that originally had MacPherson struts on the front wheels.

In contrast to the traditional L-shaped lower control arm used with MacPherson struts, Super Strut had a lower control arm divided into two parts, one of which is equipped with a camber control arm, which is connected to a specially shaped strut. As a result, a virtual kingpin axis was set inside the tire, making it possible to significantly reduce the kingpin angle from 14 degrees to 6 degrees and the spindle offset from 66 mm to 18 mm. As a result, the torque steer that is noticeable in high-output front-engine, front-wheel drive vehicles equipped with LSD is reduced. Active use of ball joints also ensures rigidity and reduces friction.

The camber control arm regulates the movement of the lower arm, so when the suspension reacts to a uneven road surface, the upper part of the upright pulls inward, causing the camber angle to change negatively. Note that the inclination of the strut body may be opposite to that of the MacPherson strut type.

While there are various advantages, there are also disadvantages. The unsprung suspension weight is heavier than the general MacPherson strut, and depending on the car model, the minimum turning radius would be increased. There are also conditions where the steering feels uncomfortable as the steering angle increases. Furthermore, because the effective range of motion of the short camber control arm is narrow, the amount of suspension travel is also affected. The behavior is stable due to the unique characteristic of camber change, when the suspension travel is minimal, and the camber change is also minimal, and when the camber control arm reaches a certain angle, the camber change is suddenly increased. Due to the narrow vehicle height range, it was not favorable to off-road driving conditions.

Although the above disadvantages were not a problem in ordinary cars where the road surface conditions did not change much and the vehicle speed was slow, the setting range that is considered best in high speed racing conditions where limited performance is necessary and required flexibility. Therefore, in the category where suspension changes are allowed, there were cases where the structure was simple, there was accumulated know-how, and the suspension was replaced with a conventional strut, which was easier to handle.

Vehicles installed

See also

Related Research Articles

<span class="mw-page-title-main">Toyota Celica</span> Automobile

The Toyota Celica is an automobile produced by Toyota from 1970 until 2006. The Celica name derives from the Latin word coelica meaning heavenly or celestial. In Japan, the Celica was exclusive to the Toyota Corolla Store dealer chain. Produced across seven generations, the Celica was powered by various four-cylinder engines, and bodystyles included convertibles, liftbacks, coupés and notchback coupés.

<span class="mw-page-title-main">Camber angle</span> Angle between a wheels vertical axis and the vehicles vertical axis

Camber angle is one of the angles made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of a wheel and the vertical axis of the vehicle when viewed from the front or rear. It is used in the creation of steering and suspension. If the top of the wheel is farther out than the bottom, it is called positive camber; if the bottom of the wheel is farther out than the top, it is called negative camber.

<span class="mw-page-title-main">MacPherson strut</span> Type of automotive suspension design

The MacPherson strut is a type of automotive suspension system that uses the top of a telescopic damper as the upper steering pivot. It is widely used in the front suspension of modern vehicles. The name comes from American automotive engineer Earle S. MacPherson, who invented and developed the design.

<span class="mw-page-title-main">Strut</span> Structural component designed to resist longitudinal compression

A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension.

<span class="mw-page-title-main">Car suspension</span> Suspension system for a vehicle

Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/handling and ride quality, which are at odds with each other. The tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires. The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.

<span class="mw-page-title-main">Toyota Supra</span> Sports car and grand tourer manufactured by Toyota Motor Corporation

The Toyota Supra is a sports car and grand tourer manufactured by the Toyota Motor Corporation beginning in 1978. The name "supra" is derived from the Latin prefix, meaning "above", "to surpass" or "go beyond".

<span class="mw-page-title-main">Toyota AE86</span> Motor vehicle

The AE86 series of the Toyota Corolla Levin and Toyota Sprinter Trueno are small, front-engine/rear-wheel-drive models within the front-engine/front-wheel-drive fifth generation Corolla (E80) range—marketed by Toyota from 1983 to 1987 in coupé and liftback configurations.

<span class="mw-page-title-main">Toyota Corona</span> Series of automobiles manufactured by Toyota

The Toyota Corona is an automobile manufactured by the Japanese automaker Toyota across eleven generations between 1957 and 2001. On launch, the Corona was Toyota's second-highest product in their range, just below the Crown. The Corona was marketed in the JDM at Toyota's Toyopet Store dealership channels, and the Corona was one of Toyota's first models exported to other global markets, followed by the smaller Toyota Corolla.

<span class="mw-page-title-main">Toyota Soarer</span> Personal luxury car/grand tourer made by Toyota

The Toyota Soarer is a personal luxury GT coupé produced from 1981 to 2005 by Toyota and sold in Japan. It was available at both Japanese Toyota dealerships called Toyota Store and Toyopet Store, and it debuted with the Z10 series, replacing the Toyopet Store exclusive Mark II coupé, the Toyota Auto Store exclusive Chaser coupé, and both the Toyota Store exclusive Crown coupé and Carina coupé.

<span class="mw-page-title-main">Double wishbone suspension</span> Automotive independent suspension design

A double wishbone suspension is an independent suspension design for automobiles using two wishbone-shaped arms to locate the wheel. Each wishbone or arm has two mounting points to the chassis and one joint at the knuckle. The shock absorber and coil spring mount to the wishbones to control vertical movement. Double wishbone designs allow the engineer to carefully control the motion of the wheel throughout suspension travel, controlling such parameters as camber angle, caster angle, toe pattern, roll center height, scrub radius, scuff, and more.

<span class="mw-page-title-main">Chapman strut</span> Type of automotive suspension design

The Chapman strut is a design of independent rear suspension used for light cars, particularly sports and racing cars. It takes its name from, and is best known for its use by, Colin Chapman of Lotus.

<span class="mw-page-title-main">Nissan Laurel</span> Series of luxury performance automobiles manufactured by Nissan

The Nissan Laurel is a two- and four-door sedan manufactured and marketed by Nissan from 1968 to 2002. Later generations added all-wheel-drive along with turbocharged engines. Introduced in 1968 as a new model positioned above the Datsun Bluebird 510, the Laurel offered the luxury of the Nissan Gloria A30 in a shorter wheelbase, and has always been the luxury version of the Skyline range for all generations, sharing engines, suspensions and handling dynamics of the popular performance coupe and sedan while having a longer wheelbase.

<span class="mw-page-title-main">Anti-roll bar</span> Device that reduces the body roll of a vehicle

An anti-roll bar is an automobile suspension part that helps reduce the body roll of a vehicle during fast cornering or over road irregularities. It links opposite front or rear wheels to a torsion spring using short lever arms for anchors. This increases the suspension's roll stiffness—its resistance to roll in turns.

<span class="mw-page-title-main">Toyota Carina</span> Motor vehicle

The Toyota Carina is an automobile which was manufactured by Toyota from December 1970 to December 2001. It was introduced as a sedan counterpart of the Celica, with which it originally shared a platform. Later, it was realigned to the Corona platform, but retained its performance image, with distinctive bodywork and interior — aimed at the youth market and remaining exclusive to Japanese Toyota dealerships Toyota Store. It was replaced in Japan by the Toyota Allion in 2001 and succeeded in Europe by the Toyota Avensis.

An active suspension is a type of automotive suspension that uses an onboard control system to control the vertical movement of the vehicle's wheels and axles relative to the chassis or vehicle frame, rather than the conventional passive suspension that relies solely on large springs to maintain static support and dampen the vertical wheel movements caused by the road surface. Active suspensions are divided into two classes: true active suspensions, and adaptive or semi-active suspensions. While semi-adaptive suspensions only vary shock absorber firmness to match changing road or dynamic conditions, active suspensions use some type of actuator to raise and lower the chassis independently at each wheel.

<span class="mw-page-title-main">Toyota Celica GT-Four</span> Motor vehicle

The Toyota Celica GT-Four is a high performance model of the Celica Liftback that was produced from 1986 to 1999, with a turbocharged 3S-GTE engine, and full-time AWD. It was created to compete in the World Rally Championship, whose regulations dictate that a manufacturer must build road-going versions of the vehicle in sufficient numbers. These vehicles are referred to as "homologation special vehicles".

<span class="mw-page-title-main">Toyota Corolla (E90)</span> Motor vehicle

The Corolla E90, introduced in 1987 for the 1988 model year, was the sixth generation of cars sold by Toyota under the Corolla nameplate. It was the last generation of Corolla to be classified as a subcompact car and the first to be exclusively front-wheel drive or all-wheel drive; the performance option of rear-wheel drive was dropped.

<span class="mw-page-title-main">Toyota Carina ED</span> Motor vehicle

The Toyota Carina ED is a compact car manufactured by Japanese automaker Toyota in 1985 as a companion to the 1984 Carina sedan. It was positioned as the four-door Celica, with a similar focus on luxury found on larger Toyota pillared hardtop sedans, like the Toyota Crown, the Toyota Mark II, Toyota Cresta and the Toyota Chaser.

<span class="mw-page-title-main">Toyota Cresta</span> Mid-size luxury car

The Toyota Cresta is a mid-size car built by Toyota. It was launched in 1980 and shared the chassis with the Mark II/Cressida, sold at Toyopet Store dealerships in Japan. The goal of the Cresta was a higher level of luxury in comparison to the Mark II, while the Chaser was the performance-oriented version of the Mark II, but sold at different dealerships. Often available with two-tone paint and more interior convenience options, with the result ending up being more similar to the Cressida sold in export markets. The Cresta was produced for five generations, and production stopped in 2001, when it was merged with the Chaser to form the short lived Verossa.

<span class="mw-page-title-main">Toyota Sprinter Trueno</span> Motor vehicle

The Toyota Sprinter Trueno is a series of compact sports coupés and hot hatches which were produced by Toyota from 1972 to 2000. The name Trueno in Spanish means thunder. In Japan, the Sprinter Trueno was exclusive to Toyota Auto Store locations, later renamed Toyota Vista Store in 1980.

References

Notes
  1. "Technical Development | Chassis". Toyota. 2012. Retrieved 2018-07-21.
  2. Tsuka, H.; Nakano, J.; Yokoya, Y. (1990-10-18). A new electronic controlled suspension using piezo-electric ceramics. IEEE Conference Publication. US: IEEE. doi:10.1109/EAIT.1990.205471.
Sources